Paediatric Neurosurgery + Hydrocephalus Flashcards
(117 cards)
1
Q
A 72-year-old man was referred by the neurologists with a 2-year history of progressive difficulty with mobility. He was previously very active and enjoyed long walks outdoors, but these have been curtailed recently because of a number of falls. On even ground he finds he has slowed and on uneven ground he frequently trips. His wife has become somewhat frustrated with his deterioration. In addition he is reported by his family as being ‘less sharp’ than he used to be and he is no longer able to complete crosswords. They also say he has become forgetful at times. His GP referred him to a neurologist where an MRI scan of the brain was performed (Fig. 53.1 ) and he has been referred for a neurosurgical opinion.
What does the MRI show?
A
Marked ventricular enlargement. No signal change around the ventricles- chronic process of enlargement.
Should review lower slices to ensure there is no mass lesion or other reason for hydrocephalus
2
Q
A 72-year-old man was referred by the neurologists with a 2-year history of progressive difficulty with mobility. He was previously very active and enjoyed long walks outdoors, but these have been curtailed recently because of a number of falls. On even ground he finds he has slowed and on uneven ground he frequently trips. His wife has become somewhat frustrated with his deterioration. In addition he is reported by his family as being ‘less sharp’ than he used to be and he is no longer able to complete crosswords. They also say he has become forgetful at times. His GP referred him to a neurologist where an MRI scan of the brain was performed (Fig. 53.1 ) and he has been referred for a neurosurgical opinion.
DDx?
A
Spinal disease would explain gait but not memory impairment.
In view of MRI diagnosis is either cerebral atrophy and a chronic progressive dementia or chronic hydrocephalus of unknown aetiology (normal pressure hydrocephalus)
3
Q
Pathophysiology of NPH
A
?Failure of CSF absoprtion either at the arachnoid granulation or due to poor CSF flow through the subarachnoid space.
If there is reduced wall tension, according to the law of Laplace, the ventricles may be prone to exapnsion even at relatively low pressures.
4
Q
Hakim’s triad
A
Ataxia
Dementia
Urinary incontinence
NPH
5
Q
Urinary incontinence in NPH
A
Different to the pattern of incontinence in spinal cord lesions (painless retention and overflow)
It is the apparently normal passage of urine in response to a full bladder without patient being aware or concerned by it.
6
Q
A 72-year-old man was referred by the neurologists with a 2-year history of progressive difficulty with mobility. He was previously very active and enjoyed long walks outdoors, but these have been curtailed recently because of a number of falls. On even ground he finds he has slowed and on uneven ground he frequently trips. His wife has become somewhat frustrated with his deterioration. In addition he is reported by his family as being ‘less sharp’ than he used to be and he is no longer able to complete crosswords. They also say he has become forgetful at times. His GP referred him to a neurologist where an MRI scan of the brain was performed (Fig. 53.1 ) and he has been referred for a neurosurgical opinion.
MRI shows ventriculomegaly
How would you proceed?
A
DDx is patients with a degenerative neurological condition causing dementia and true NPH.
It can be difciult to differentiate between these two and subsequently to identify those patients who may benefit from CSF diversion.
7
Q
Hydrocephalus ex vacuo
A
Cerebral atrophy and subsequent ventricular expansion into the shrinking brain due to reduced wall tension
8
Q
Possible diagnostic tests in ?NPH
A
Measurement of CSF pressure by ICP monitoring or LP- if there are B-waves (an ICP pressure of >20mmHg for >5 minutes)
Baseline pressure is usually normal and an absence of B-waves does not exlude the diagnosis.
Therapeutic CSF drainage is an alternative as it will temporarily mimic the action of a shunt. Initial baseline physiotherapy and psychological Ax followed by LP or lumbar drain for 24-48h.
After the post-drainage period the patient should be monitored for improvement in gait (e.g. timed 10m walk) and cognitive function (e.g. repeat MSE)
9
Q
What is a concern in placing shunts in patients with very large ventricles?
A
Overdrainge of CSF may produce subdural collections and haematomas
10
Q
Regulation of CSF pressure in VP shunt
A
CSF pressure in VP shunt is regulated by the valve.
High pressure valves open only when CSF pressure is high.
Low pressure when CSF is high or normal and close at low pressure.
11
Q
VP shunts in patients with NPH
A
Ultimately patients with NPH require the shunts to be open at low pressure though doing so immediately with a shunt risks subdural haematoma.
Solution is to place a variable pressure valve in the shunt that can be adjusted externally.
Initially valve is set at high pressure and progressively lowered.
Theory is to allow the brain to expand gradually rather than for it to collapse quickly.
12
Q
Cotugno
A
Credited with discovering CSF
13
Q
Dandy
A
Experimental verification of CSF circulation
14
Q
Components of the ventricular system and CSF circulation
A
Two lateral paired ventricels
Communicate with third ventricle via the foramen of Munro
Third ventricle-> fourth ventricle via the aqeuduct of Sylvius
Fourth ventricle comunicates with cranial and spinal subarachnoid space via the foramen of Magendie and the paired foramina of Luschka
15
Q
Secretion of CSF
A
70% from the choroid plexus but some is derived from capillary ultrafiltrate and metabolic water production
Energy-dependent process (Na/K ATPase) with sodium being secreted in to subarachnoid space and water following it
16
Q
Rate of CSF production /day
A
450mL/day
17
Q
Total volume of CSF
A
150ml with 25mL in the ventricular system (remainder is in the spinal canal and subarachnoid space)
18
Q
Location of choroid plexus
A
Floor, body and roof othe temporal horns of the lateral ventricles
Roof of third ventricle
WIthin the fourth ventricle
19
Q
Composition of the choroid plexus
A
Single layer of cuboidal epithelial cells surrounding blood capillaries.
20
Q
Absorption of CSF
A
Arachnoid granulations in the superior sagittal sinus.
Operates a pressure-dependent valve, transmitting CSF when the ICP>venous presssure.
Some CSF is also absorbed by veins.
Rate of absorption regulates CSF pressure and production is relatively constant.
21
Q
Reduction of CSF production
A
Decreased by carbonic anhydrase inhibitors (acetazolamide) and noradrenaline.
Increased by CO2 and volatile anaesthetics
22
Q
What part of the brain regulates CSF production
A
Raphe nuclei
23
Q
Def: hydrocephalus
A
Results from an imbalance between production and absorption of CSF resulting in increased CSF volume and pressure.
Must be distinguished from ventriculomegaly (i.e. dilated ventricles with low or normal CSF pressure) and NPH.
24
Q
Characteristic of acute hydrocephalus on neuroimaging
A
Periventricular lucency typically at the tips of the frontal horns of the lateral ventricles.
This represents CSF egress into the adjacent white matter and indicates high intraventricular pressure
25
a Brain CT shows ventricle enlargement and periventricular lucency. b Post-ventriculoperitoneal shunting, ventricle size is decreased
26
Acute hydrocephalus
Neurosurgical emergency which if left untreated can rapidly lead to brain herniation and death.
27
Why can infants tolerate greater increases in CSF volume
Due to non-union of the cranial sutures
28
Classification of acute hydrocephalus
Obstructive or communicating
29
Obstructive hydrocephalus
Resultsfrom obstruction of CSF flow within the ventricular system
30
Communicating hydrocephalus
Results from obstruction at the arachnoid villi
31
Radiological findings in obstructive hydrocephalus
Proximal ventricles dilated
Distal relatively small
32
A 6-week-old baby boy was referred by the paediatricians. A health visitor alerted the GP as the child’s head circumference was raised on two successive measurements and she was concerned. The child was born by a normal vaginal delivery. The pregnancy was uneventful; the mother had already had two older children with no medical prob- lems. Both the 12- and 20-week ultrasound scans were normal. Since birth the baby had been feeding well and not crying unduly. He has not had other symptoms such as fevers or unusual patterns of vomiting.
How should the baby be examined neurologically?
General conscious state- alert, interacting normally, miserable or drowsy
Pupils and gaze should be assessed. Impaired upward gaze- sunsetting- may signal raised ICP.
Palpate fontanelle- bulging fontanelle is consistent with raised ICP.
Measure the head circumference
Tone and movements of the limb noted.
33
A 6-week-old baby boy was referred by the paediatricians. A health visitor alerted the GP as the child’s head circumference was raised on two successive measurements and she was concerned. The child was born by a normal vaginal delivery. The pregnancy was uneventful; the mother had already had two older children with no medical prob- lems. Both the 12- and 20-week ultrasound scans were normal. Since birth the baby had been feeding well and not crying unduly. He has not had other symptoms such as fevers or unusual patterns of vomiting.
On examination the baby was alert. The anterior fontanelle was tense and bulg- ing. His head circumference was 44.2cm (well above the 95th centile). It was 38cm at birth (around the 90th centile
What is the ddx for an enlarged head in a baby?
Macrocephaly is not always pathological, some children have a large head with normal sized ventricles and no underlying cause.
Pathological enlargment of the head is most commonly caused by hydrocephalus either obstructive or communicating.
Macrocephaly without hydrocephalus is less common and may be due to large SOL
Increased volume of brain tissue may enlarge the head e.g. in neurocutaneous syndromes such as neurofibromatosis.
Venous HTN due to AVM may cause hydrocephalus.
Endocrinopathies e.g. hypoparathyroidism or adrenal insufficiency
34
Causes of obstructive hydrocephalus in a baby
Tumour
Aqueduct stenosis
35
Cause of communicating hydrocephalus in a baby
Perinatal haemorrhage
Meningitis
36
Large SOLs in a baby causing macrocephaly
Astrocytoma
Large arachnoid cyst
Chronic SDH
37
What are the associated features of raised CSF pressure in a baby?
Apart from bulging fontanelle include distended scalp veins.
Loss of upward gaze (Parinaud's syndrome)
38
Pathophysiology of Parinaud's syndrome
Parinaud's syndrome, also known as dorsal midbrainsyndrome, vertical gaze palsy, and sunset sign, is an inability to move the eyes up and down. It is caused by compression of the vertical gaze center at the rostral interstitial nucleus of medial longitudinal fasciculus (riMLF).
39
Features of Parinaud's Syndrome
Caused by dorsal midbrain syndrome.
Lid retraction (Collier)
Light near dissociation
Convergence retraction (nystagmoid) (due to preserved CN 6 action)
Upgaze paresis due to compression of the rostral MLF
40
A 6-week-old baby boy was referred by the paediatricians. A health visitor alerted the GP as the child’s head circumference was raised on two successive measurements and she was concerned. The child was born by a normal vaginal delivery. The pregnancy was uneventful; the mother had already had two older children with no medical prob- lems. Both the 12- and 20-week ultrasound scans were normal. Since birth the baby had been feeding well and not crying unduly. He has not had other symptoms such as fevers or unusual patterns of vomiting.
The baby undergoes a CT scan (Fig. 54.1). What is the diagnosis? Does the sagit- tal reformat of the scan (Fig. 54.2) make the diagnosis any clearer?
There is massive dilatation of the lateral ventricles.
The fourth venricle is small.
Therefore this is a non-communicating hydrocephalus with an obstruction in either the third ventricle or between the fourth and third ventricles.
Obstruction in the third ventricle would most commonly be a tumour. Obstruction between the third and fourth ventricles could again be a tumour in the pineal region or aqueductal stenosis
The sagittal slice shows the enlarged third and the small fourth ventricle.
The pineal region appears normal. The cerebral aqueduct is not seen clearly at all.
Therefore the diagnosis is aqueductal stenosis
41
A 6-week-old baby boy was referred by the paediatricians. A health visitor alerted the GP as the child’s head circumference was raised on two successive measurements and she was concerned. The child was born by a normal vaginal delivery. The pregnancy was uneventful; the mother had already had two older children with no medical prob- lems. Both the 12- and 20-week ultrasound scans were normal. Since birth the baby had been feeding well and not crying unduly. He has not had other symptoms such as fevers or unusual patterns of vomiting.
The child likely has aqueductal stenosis, what are the treatment options
The child needs CSF diversion on a fairly urgent basis. If there is any doubt about the underlying cause of hydrocephalus, an MRI might be performed which would give a better appreciation of the anatomy of the cerebral aqueduct but is unlikely to change management.
42
What are the two forms of permanent CSF diversion?
VP shunt
Endoscopic third ventriculostomy
43
What is the difference between VP shunt and ETV.
VP shunt is the default option for both communicating and non-communicating hydrocephalus as it allows CSF to be absorbed outside the CNS.
ETV requires functioning CSF absorption pathways and a patent subarachnoid space as it creates a direct pathway from the third ventricles to the basal cisterns and subarachnoid space. It is only likely to be successful in patients with non-communicating hydrocephalus.
44
Why is ETV considered superior to VP shunt?
Allows physiological CSF absorption, problems of siphoning causing overdrainage are avoided.
The risk of acute blockage is lower with ETV than with shunt.
45
Features of aqueduct stenosis
The form of non-communicating hydrocephalus most amenable to ETV as CSF composition is entirely normal, unlike post-haemorrhagic or post-meningitic hydrocephalus).
The bar to CSF absorption is anatomical, and can be bypassed by the creation of a stoma in the floor of the third ventricle.
46
Why are success rates higher for ETV in adults than in babies
Success rates of ETV in adults can be up to \>90%.
Far lower in babies for reasons that may include under-development of the subarachnoid space because of a lack of pressure during gestational CNS development.
Some neurosurgeons would place a shunt with the plan that if the the first shunt blocks the child would undergo ETV to make them shunt independent.
47
Neurological significance of fetal anomaly scanning at 20/40
Incorporates detailed assessment and development of the brain and spine as well as the vetnricular syndrome.
48
Describe the MRI findings
MRI scan of a twin pregnancy with the uppermost fetus showing signs of marked ventricular dilatation.
49
A 32-year-old woman is referred to the outpatient clinic. She is 36 weeks pregnant with a baby who has been diagnosed with spina bifida. A myelomeningocoele is present at L4/5. There is an associated Chiari malformation and hydrocephalus.
How should this patient be counselled?
The mother should be aware of the implications of the diagnosis:
Method of birth- C-section may reduce risk of infection.
Uncertain nature of neurological deficit.
Need for early surgery, within 48h, to close the defect to prevent meningitis and preserve neural function- will not reverse pre-existing deficits.
Complications of the operation.
The need to monitor the progression of hydrocephalus in the post-natal period and the potential need for CSF diversion.
Potential for neurological, orthopaedic and cognitive problems in later life.
The availability of the MDT to provide guidance
50
Why do Chiari malformations and hydrocephalus occur with myelomeningocoeles?
The myelomeningocoele results from the failure of the neural tube to close in the third week of embryonic life. This results in defective formation of the cranial vesicles, leading to a small posterior fossa.
The fetal cerebellum and brainstem grow into a diminished space, causing downward displacement through the foramen magnum.
Hydrocephalus arises as a direct result of this due to obstruction of CSF outflow from the posterior fossa
51
What other abnormalities are associated with this myelomeninocoeles
Abnormal gyri
Agenesis of the corpus callosum
Cerebellar dysplasia
Abnormal anatomy of the ventricular system and brainstem
52
What are the main complications of surgical repair of myelomeningocoele?
Wound breakdown
CSF leak
Meningitis
Dermoid inclusion tumours
53
What are the potential complications in later life following myelomeningocoele repair?
Tethered cord
Hydrocephalus
Shunt problems.
Chiari malformation may lead to brainstem compression and syringomelia
54
When does the neural tube close?
3/40
55
A 32-year-old woman is referred to the outpatient clinic. She is 36 weeks pregnant with a baby who has been diagnosed with spina bifida. A myelomeningocoele is present at L4/5. There is an associated Chiari malformation and hydrocephalus.
The baby is delivered by Caesarean section. It was noted
to have a small head but the anterior fontanelle was normal. There was good tone in the limbs, and the arms, hips, and knees were moving. Fig. 55.1 shows the myelomeningocoele. How should the baby be nursed and what should be done with the defect pending surgery?
The baby should be nursed on its front or side and a sterile moist dressing used to keep the defect covered.
56
What post-operative precautions are necessary following surgical closure of myelomeningocoele?
Wound must be inspected to check the integrity of closure and for signs of CSF leak.
The development of hydroecephalus must be monitored by serial head circumference measurements or cranial ultrasound.
57
What is the subsequent risk after having a child born with myelomeningocoele?
10% risk of offspring having the condition.
The use of prophylactic folic acid has been shown to reduce the incidence of spina bifida
58
A 32-year-old woman is referred to the outpatient clinic. She is 36 weeks pregnant with a baby who has been diagnosed with spina bifida. A myelomeningocoele is present at L4/5. There is an associated Chiari malformation and hydrocephalus.
The baby went on to have myelomeningocoele repair.
It subsequently developed hydrocephalus and underwent a VP shunt.
Two years later, the infant is referred to the outpatient clinic with increasing unsteadiness. What is the differential diagnosis?
Shunt malfunction
Tethered cord
Chiari malformation
Hydromyelia
Syringomyelia.
Shunt dysfunction is probably the most common cause in this population.
59
A 20-year-old woman is referred by the orthopaedic surgeons. She has been complain- ing of rather indistinct bilateral leg pains, a little worse on the right side. These have been present for about 2 years and have been tolerable, but more recently she has found that the right lower leg pain has subsided and she has had some difficulty, par- ticularly with the right foot, when walking and running. Her medical history is rele- vant only for removal of a fatty lump from her lower back as a child, which was performed abroad. Since childhood she has never developed proper bladder control and voids using intermittent self-catheterization.
Examination finds absent ankle jerks bilaterally. The right foot is arched more than the left and there is some contracture of the calf, holding it in slight plantarflexion.
Bilateral leg pain may be caused by a number of pathologies including peripheral neuropathy, sciatica, hip or knee disease.
The pes cavus suggests slow denervation of the muscles maintaining the foot arch.
The combination of symptoms suggests a lesion affecting the cauda equina which has been present for many years.
The fatty lump is a clue to likely underlying spinal dysraphism.
60
Spinal dysraphism
Spectrum of conditions varying from the severe e.g. open myelomeningocoele seen antenatally and requiring closure after birth with a high incidence of associated severe neurological deficits.
Occult spina bifida defects lie at the other end of the spectrum which may be asymptomatic throughout life an only detected incidentally on imaging or clinical exam
61
What is the underlying problem in spinal dysraphias?
Failure of formation of the posterior aspects of the neural arch.
These structures are the SC, arachnoid, dura, fat, bone and skin.
In open myelomeningocele there is neural tissue on view with CSF leak from birth.
The milder versions are typically covered with skin and may have a hairy patch or dimple in association with underlying bony defect.
A lipoma may be present under the skin and running down and mixed in with the nerve roots
62
A 20-year-old woman is referred by the orthopaedic surgeons. She has been complain- ing of rather indistinct bilateral leg pains, a little worse on the right side. These have been present for about 2 years and have been tolerable, but more recently she has found that the right lower leg pain has subsided and she has had some difficulty, par- ticularly with the right foot, when walking and running. Her medical history is rele- vant only for removal of a fatty lump from her lower back as a child, which was performed abroad. Since childhood she has never developed proper bladder control and voids using intermittent self-catheterization.
Examination finds absent ankle jerks bilaterally. The right foot is arched more than the left and there is some contracture of the calf, holding it in slight plantarflexion.
n MRI is done (sagittal and axial T2) (Fig. 56.1). What is shown (A–C)? What is the likely cause of her symptoms? What would you advise her?
The vertebral bodies and discs are normal and well aligned and the spinal canal is of normal calibre.
However, the SC does not end normally at L1/2 rather, it continues and its termination is indistinct but related to an area with overlying scar and a defect in the lumbar fascia (A).
The bony elemenets do not form normally and there is a suggestion that the spinal subarachnoid space communicates with the subcutaneous fat opposite the S2 segment B
The axial image confirms the low-lying SC lying dorsally in the thecal sac and related to the soft tissues overlying it (C).
There is agenesis of the laminae bilaterally and hence the facet joints are abnormal.
This is a spyinal dysraphic defect with low-lying cord.
In combination with the clinical features of progressive leg symptoms, the diagnosis of spinal cord tethering with the cord being stretched by its attachment to the subcutaneous lipoma.
The progressive nature of her symptoms makes conservative managemnet unattractive.
63
What is generally the rule for spinal cord disease
Lost function- specifically sphincter control, sensation or motor function will not be regained with surgery which only prevents deterioration.
Once a definite progression of symptoms is established, surgery should be strongly considered.
64
What is the aim for surgery in the patient described with SC tethering
Aim to free the low-lying cord and the cauda equina from the intradural component of the lipoma and associated thickened arachnoid.
It risks damaging the nerve roots and the cord as there will be no normal anatomy at the site of the dysraphic defect.
65
Surgical approach to repair of cord tethering.
Laminectomy and durotomy at least one level above the site of presumed tethering to identify the normal dura and then open it to free neural structures, progressing caudally through the defect.
66
Why are cord tethering syndromes more common in children
As the cord and spine grow at a different rate, unmasking the tethering.
67
A 20-year-old woman has been seen by the neurologists. She has a 3-week history of
severe headaches and progressive visual failure, and originally saw an optician who
suggested that she needed to be seen in hospital. She has an approximately symmetrical. loss of visual acuity, not correctable by glasses, which is now 6/24 bilaterally. In
addition, she describes the edges of her vision closing in and feels that she is ‘looking
down a tunnel’. She has no diplopia, no vomiting, no seizures, and no focal neurological
symptoms or signs. Fundoscopy shows gross papilloedema bilaterally.
What is the cause of her visual failure?
She has raised ICP
The pattern of visual failure with the described field defect and the loss of acuity is due to swelling of the optic nerve.
She may have an enlarged scotoma bilaterally.
The lack of focal neurological deficit suggets that the raised pressure is due to either hydrocephalus or a mass lesion large enough to cause raised ICP but otherwise remaining undetected.
Such a lesion woudl have to be located in non-eloquent brain, typically the right frotal temporal lobe.
68
A 20-year-old woman has been seen by the neurologists. She has a 3-week history of
severe headaches and progressive visual failure, and originally saw an optician who
suggested that she needed to be seen in hospital. She has an approximately symmetrical
loss of visual acuity, not correctable by glasses, which is now 6/24 bilaterally. In
addition, she describes the edges of her vision closing in and feels that she is ‘looking
down a tunnel’. She has no diplopia, no vomiting, no seizures, and no focal neurological
symptoms or signs. Fundoscopy shows gross papilloedema bilaterally.
If hydrocephalus is the cause, what are the possible lesions?
She may have a small benign obstructive lesion e.g. colloid cyst or meningioma in the third ventricle.
A fourth ventricular tumour is a possibility but there is usually a history of imbalance or other cerebellar dysfunction.
Hydrocephalus due to aqueduct stenosis usually presents in childhood but may occasionally become evident in adulthood for reasons that are unclear.
Other causes usually have symptoms of the underyling disease early in their course.
IIH (pseudotumour cerebri) or a major venous sinus thrombosis e.g. sagittal sinus occlusion
69
A 20-year-old woman has been seen by the neurologists. She has a 3-week history of
severe headaches and progressive visual failure, and originally saw an optician who
suggested that she needed to be seen in hospital. She has an approximately symmetrical
loss of visual acuity, not correctable by glasses, which is now 6/24 bilaterally. In
addition, she describes the edges of her vision closing in and feels that she is ‘looking
down a tunnel’. She has no diplopia, no vomiting, no seizures, and no focal neurological
symptoms or signs. Fundoscopy shows gross papilloedema bilaterally.
An MRI has been done.
What are the key findings?
The key findings supportive of IIH are normal-sized ventricles and cortical CSF spaces, best seen on the T2 sequences.
The sagittal image shows low signal intensity within the pituitary fossa consistent with CSF replacing pituitary tissue- the empty sella.
The venogram shows defects in both transverse sinuses laterally approaching the transverse-sigmoid junciton but they are not though to be thrombosed, these are all key features of BIH.
70
Features of IIH
AKA pseudotumour cerebri.
More commonly affects women and is asociated with obesity.
May result in severe and even complete visual failure.
The aetiology remains unknown but CSF diversion is still considered definitive treatment
71
A 20-year-old woman has been seen by the neurologists. She has a 3-week history of
severe headaches and progressive visual failure, and originally saw an optician who
suggested that she needed to be seen in hospital. She has an approximately symmetrical
loss of visual acuity, not correctable by glasses, which is now 6/24 bilaterally. In
addition, she describes the edges of her vision closing in and feels that she is ‘looking
down a tunnel’. She has no diplopia, no vomiting, no seizures, and no focal neurological
symptoms or signs. Fundoscopy shows gross papilloedema bilaterally.
MRI shows features in keeping with IIH.
How would you proceed?
The rate of visual deterioration is of crucial importance in deciding her management.
Most patients are managed mdically by a combination of neurology and ophthalmology.
Her assessment should include:
Detialed ophthalmological examination including perimetry tests
LP to measure opening pressure, for CSF analysis and to remove enough CSF therapeutically to lower the pressure by half.
The opening pressure for a patient with BIH may be higher than 40cm, daining enough to lower it below 20cm H2O will relieve headaches where they present and also stabilise visual failure.
72
Medical managmeent of IIH
Acetazolamide is usually given to reduce CSF production and may be sufficient for some months or years.
Many patients will become refractory to acetazolamide and require shunting.
73
Shunt therapy for IIH
Because the ventricles are small/normal there is often a preference to divert CSF with a lumbar-peritoneal shunt. This avoids the risks of cranial surgery.
Lumbar-peritoneal shunts have a greater tendency to block or displace and a number of patients subseuquently require a ventricular shunt.
74
Venous sinus stenoses in IIH
There has been great interest in the stenoses seen on venography which have been postulated to be the primary causative factor in IIH.
As a conseuqences, some centres use endovascular techniques to stent the sinuses with the expectation that this will improve CSF pressure.
Small series have reported good outcomes.
The counter-argument is that raised ICP will cause venous obstruciton, which is supported by venograms shortly after therapeutic LPs showing resolution of the previously seen stenosis after reduction in CSF pressure.
75
A 20-year-old woman has been seen by the neurologists. She has a 3-week history of
severe headaches and progressive visual failure, and originally saw an optician who
suggested that she needed to be seen in hospital. She has an approximately symmetrical
loss of visual acuity, not correctable by glasses, which is now 6/24 bilaterally. In
addition, she describes the edges of her vision closing in and feels that she is ‘looking
down a tunnel’. She has no diplopia, no vomiting, no seizures, and no focal neurological
symptoms or signs. Fundoscopy shows gross papilloedema bilaterally.
She undergoes VP shunting for IIH
Three weeks after shunt placement she attends the ward urgently. She has had
recurrent headaches for the last 36 hours with the same features as the headaches
she had preoperatively, although she has no visual failure as yet. She has also
noticed an uncomfortable tense lump at the site of the abdominal wound where
the distal end of the shunt was inserted. She has not been febrile or vomiting.
On examination the cranial end of the shunt is well healed and not tender. The
abdominal wound is also well healed, but there is a tense firm limp underneath it
which is tender. There is no guarding or peritonism.
DDx?
The recurrence suggests that the shunt is not working.
Given the size of the ventricles it is possible that they have collapsed around the shunt and blocked it.
However, the tender abdominal lump suggests a local abdominal problem causing hte shunt to fail.
This might be peritoneal scarring from previous surgery by the most likely cause is that the shunt has become pulled out of th epeirtoneum and the CSF is collecting subcutaneously at high pressure causing local tendenress and raised CSF pressure.
76
A 20-year-old woman has been seen by the neurologists. She has a 3-week history of
severe headaches and progressive visual failure, and originally saw an optician who
suggested that she needed to be seen in hospital. She has an approximately symmetrical
loss of visual acuity, not correctable by glasses, which is now 6/24 bilaterally. In
addition, she describes the edges of her vision closing in and feels that she is ‘looking
down a tunnel’. She has no diplopia, no vomiting, no seizures, and no focal neurological
symptoms or signs. Fundoscopy shows gross papilloedema bilaterally.
She undergoes VP shunting for IIH
Three weeks after shunt placement she attends the ward urgently. She has had
recurrent headaches for the last 36 hours with the same features as the headaches
she had preoperatively, although she has no visual failure as yet. She has also
noticed an uncomfortable tense lump at the site of the abdominal wound where
the distal end of the shunt was inserted. She has not been febrile or vomiting.
On examination the cranial end of the shunt is well healed and not tender. The
abdominal wound is also well healed, but there is a tense firm limp underneath it
which is tender. There is no guarding or peritonism.
XR of th shunt are taken. What do they show?
The cranial tubing is unremarkable, however at the abdominal end the shunt tubing is coiled up in a small area in the RUQ.
This suggests that it has pulled out of the peritoneum and CSF is failing to be absorbed at low enough pressures to keep her headaches at bay.
A lateral XR would confirm this but is not necessary given the clinical picture.
This is a more common problem in obese patietns beacuse of technical difficulties with the abdominal componenet of the shunt surgery
77
A 20-year-old woman has been seen by the neurologists. She has a 3-week history of
severe headaches and progressive visual failure, and originally saw an optician who
suggested that she needed to be seen in hospital. She has an approximately symmetrical
loss of visual acuity, not correctable by glasses, which is now 6/24 bilaterally. In
addition, she describes the edges of her vision closing in and feels that she is ‘looking
down a tunnel’. She has no diplopia, no vomiting, no seizures, and no focal neurological
symptoms or signs. Fundoscopy shows gross papilloedema bilaterally.
She undergoes VP shunting for IIH
Three weeks after shunt placement she attends the ward urgently. She has had
recurrent headaches for the last 36 hours with the same features as the headaches
she had preoperatively, although she has no visual failure as yet. She has also
noticed an uncomfortable tense lump at the site of the abdominal wound where
the distal end of the shunt was inserted. She has not been febrile or vomiting.
On examination the cranial end of the shunt is well healed and not tender. The
abdominal wound is also well healed, but there is a tense firm limp underneath it
which is tender. There is no guarding or peritonism.
XRs of the shunt show that it is likely displaced from the peritoneum.
How should this be managed?
The bottom end of the shunt should be explored and re-implanted in the peritoneal cavity.
It may be sutured carefully to the rectus sheath to reduce the chance of recurrence.
Careful closure of the peritoneum and rectus sheath may also prevent herniation of the abdominal contents, including the shunt tubing.
General surgical input with a laprasocope may make this easier.
78
A 33-year-old man who had a ventriculoperitoneal shunt in infancy for congenital hydrocephalus, which has never been revised, presented to the emergency department with increasing headaches, nausea, and vomiting.
What are the important questions to ask in the history
Essential questions about the shunt:
Location of distal end- peritoneum, pleura, SVC
Type of shunt: pressure setting, programmable
Diagnosis requiring shunt
When it was inserted
Number and nature of revision
About the symptoms:
Associated withn raised ICP (blocked shunt)- headaches, nausea, vomiting, visual disturbance
Infection- pyrexuia, altered mental state
Associated with distal end of the shunt- abdominal pain
79
What are the bedside tests that can be used to assess a potentially blocked shunt?
Fundoscopy
Pressing on reservoir
Tapping the shunt
80
Papilloedema in ?blocked shunt
Indicates raised ICP and whether the shunt is functioning adequately
81
Pressing on the reservoir in ?blocked shunt
May indicate whether the proximal- ventircular cathter end, is working
Press the valve and release: if the valve releases the ventricular catheter is patent
If it depresses and does not fill, blockage of the ventricular catheter is a possibility altough low ICP may also be possible.
Even if the valve fills, a blocked shunt is not excluded as shunt tubing distal to the valve may still be blocked.
This is an unreliable technique, especially in older shunts
82
Tapping the shunt in ?blocked shunt
Involves passing a 25g needle into the reservoir of the shunt valve. A manometer may be connected
If CSF easily aspirated at high pressure ?distal blockage
CSF easily aspirated at low pressure- shunt may be working, does not excluude blockage
CSF difficult to aspirate- suggests proximal blockage
83
What are the two radiological invetsigaitons that cna be perofrmed for a blocked shunt?
XR shunt series enables the shunt tubing to be examiend for breakages or disconnections
CTH- allows assessment of ventricle size. Some patients can have stiff ventricles that do not dilate when under pressure and so a normal CT does not exlcude shunt blockage. Ultiamtely the decision to explore the shunt for potetnial blockage depends on careful assessment of the patient's sympomts
84
A 33-year-old man who had a ventriculoperitoneal shunt in infancy for congenital hydrocephalus, which has never been revised, presented to the emergency department with increasing headaches, nausea, and vomiting.
How should this patient be investigated?
Clinical examination: ?papillodema; shunt valve assessed for refilling
Shunt series XR
CT scan to assess size of the ventricles
Check bloods for infection.
Tapping the shunt can be avoided as it carriess the risk of introducing infection
85
A 33-year-old man who had a ventriculoperitoneal shunt in infancy for congenital hydrocephalus, which has never been revised, presented to the emergency department with increasing headaches, nausea, and vomiting.
Investigations are as follows.
◆ fundoscopy—patient did not tolerate procedure
◆ shunt valve—does not refill on compression
◆ shunt series X-rays—no abnormalities found
◆ serum inflammatory markers—normal
◆ CT brain is shown in Fig. 58.1.
CTH shown
What will you do next?
The shunt catheter is positoned in the ventricle and the ventricles are not particularly dilated.
An old CT when the shunt was nknown to be working was not avialble.
Shunt infeciton is unlikely.
The shunt valve not filling is consistent with obstruction.
Confrimation could be sought by measuring CSF pressure.
LP carries less risk of infection, if raised opening pressure suggests shunt not working.
This patient proceded to surgery and the ventricular catheter was found to be blocked and had adhered to brain over mayn years. A new catheter was inserted.
86
What should happen after shunt revision
CTH so baseline scan available to allow for characterisation of shunt associated problems in the future
87
A district general hospital refers a 30-year-old woman who presented to the emer- gency department following three generalized tonic–clonic seizures. She has a VP shunt which was inserted following traumatic intracranial haemorrhage at 15 months of age. She has had numerous shunt revisions, the last of which was 3 months ago. For the past 2 days, her family noted that she was quiet and not her usual self, although she herself did not complain of any symptoms. On arrival at the local emergency depart- ment she was post-ictal and drowsy but responsive with a GCS of 12/15 (E3, V3, M6). During assessment she deteriorates to a GCS of 3/15 and is intubated. Her pupils are size 3, equal and reactive. Her CT scan is shown in Fig. 59.1.
Describe the appearances on the scan (Fig. 59.1). What would be your advice over the telephone?
The third ventricle and occipital horns of the lateral ventircles are dilated. A ventricular catheter traverse the right lateral ventricle and lies in the third ventricle.
Some low density, which may represent transpendymal flow and raised ICP is seen around the frontal horns.
Clinical deterioration, ventirculomegaly and transepndymal flow are consistent with a blocked shunt.
This patient requires urgent transfer to a neurosurgical centre.
The local clinicians may be asked to aspirate some fluid from the shunt or perform an LP if transfer is going to be delayed.
Bloods are necessary
88
A district general hospital refers a 30-year-old woman who presented to the emer- gency department following three generalized tonic–clonic seizures. She has a VP shunt which was inserted following traumatic intracranial haemorrhage at 15 months of age. She has had numerous shunt revisions, the last of which was 3 months ago. For the past 2 days, her family noted that she was quiet and not her usual self, although she herself did not complain of any symptoms. On arrival at the local emergency depart- ment she was post-ictal and drowsy but responsive with a GCS of 12/15 (E3, V3, M6). During assessment she deteriorates to a GCS of 3/15 and is intubated. Her pupils are size 3, equal and reactive. Her CT scan is shown in Fig. 59.1.
A scan from a recent hospital admission (during which the shunt was revised) is shown in Fig. 59.2. Comment on the appearances and its relevance to the current presentation.
The ventircles are larger on the previous scan. A shunt catheter is seen with its tip in the right frontal horn of the lateral ventircle. There is more transependymal flow than on the most recent scan.
In other words this scan looks better than the previous one. It is important to establish whether this scan was before or after the most recent revision.
This does not necessarily exclude blockage as there may have been initial improvement followed by deterioration.
Seizures or coma from a metabolic cause are a possibility and should be considered although priority should given to exploring the shunt.
Infection needs to be included given the recent revision.
89
A district general hospital refers a 30-year-old woman who presented to the emer- gency department following three generalized tonic–clonic seizures. She has a VP shunt which was inserted following traumatic intracranial haemorrhage at 15 months of age. She has had numerous shunt revisions, the last of which was 3 months ago. For the past 2 days, her family noted that she was quiet and not her usual self, although she herself did not complain of any symptoms. On arrival at the local emergency depart- ment she was post-ictal and drowsy but responsive with a GCS of 12/15 (E3, V3, M6). During assessment she deteriorates to a GCS of 3/15 and is intubated. Her pupils are size 3, equal and reactive. Her CT scan is shown in Fig. 59.1.
The patient arrives at your hospital intubated and ventilated. Where will you direct the patient and what will your immediate actions be?
To OR immediately as an operation can rapidly and simultaneously address diagnosis and management- blocked shunt or infection and management- revise shunt or remove if infected.
If the shunt is found to be patent and the CSF sterile, another cause for the neurological deterioration must be sought.
The pupillary responses should be checked on a regular basis, in this case on the patient's arrival in the depratment and before sx
90
A district general hospital refers a 30-year-old woman who presented to the emer- gency department following three generalized tonic–clonic seizures. She has a VP shunt which was inserted following traumatic intracranial haemorrhage at 15 months of age. She has had numerous shunt revisions, the last of which was 3 months ago. For the past 2 days, her family noted that she was quiet and not her usual self, although she herself did not complain of any symptoms. On arrival at the local emergency depart- ment she was post-ictal and drowsy but responsive with a GCS of 12/15 (E3, V3, M6). During assessment she deteriorates to a GCS of 3/15 and is intubated. Her pupils are size 3, equal and reactive. Her CT scan is shown in Fig. 59.1.
At surgery, the shunt tubing is found to be patent throughout and the CSF pressure is low. A sample of CSF was sent to the microbiology laboratory intraoperatively, and the following results were obtained: red cell count, 167; white cell count, 1035 (92% polymorphs); Gram stain, Gram negative rods. What is the management?
The findings are consistent with bacterial infection
91
Management of shunt-associated infections
Remove entire shunt system if feasible (if patient is not fit for surgery, Abx may be used with shunt in situ but this is associated with worse outcome)
Provide interim CSF drainage with an EVD. This enables continuous drainage of CSF, CSF sampling to monitor the response of infection and administration of intrathecal Abx if necessary
Identify source of infection
IV Abx
Re-insert shunt when CSF is sterile
92
What are the routes by which ventircular catheters become infected?
Contamination of the shunt by the patient's skin flora at time of insertion
Breakage of the skin overlying the shunt
Contamination of the distal end of the shunt (e.g. peritonitis for ventriculopreitoneal shunts)
Haematogenous
93
What is the difference between meningitis and ventriculitis and which affects patients with infected shunts?
Meningitis involves inflammation of the mengines whereas ventriculitis involves inflammation of the ventricular ependyma.
Patients with an infected shunt or EVD initialy develop ventirculitis, they may or may not develop meningitis depending on the extent of residual communcation between the ventricular system and the subarachnoid space
94
Are there any evidence-based guidlines for the treatment of shunt-associated ventriculitis/meningitis?
Better outcomes are achieved by removing the shunt system rather than leaving it in situ.
The recommendation is that Abx should be continued for 7-14 days and negative CSF cultures should be obtained throughout this period before the shunt is re-inserted.
Intrathecal Abx may be considerd in resitant cases or when the shunt apparatus cannot be removed.
95
WCC in normal CSF
\<5
96
RBCs in the CSF
Can be due to traumatic LP, intracranial haemorrhage or surgical procedure
The presence of red blood cells in the CSF may elevate the WCC in the absence of infection
97
WCC: RCC in CSF
The normal ratio of white blood cells to RBC in blood contaminated CSF is assumed to be 1 WBC to 500-750 RBCs to mirror the ratio in whole blood.
The white cell count can be corrected in the presence of RBCs.
98
A 6-month-old boy presents via the paediatricians with progressively enlarging head
circumference. His head now measures 51.5cm, which makes it far above the 95th
centile (5th to 95th centile range 41.5–46cm). There is no medical history of note; he
was born by ventouse delivery at 38 weeks and is developmentally normal. Examination
finds that there is a bulging fontanelle but no loss of upgaze, and the boy seems alert
and normal apart from his head, which is clearly enlarged.
CT shows grossly dilated ventricles 2o to idiopathic hydrocephalus
Would you have any concerns about shunting this boy over and above the usual
concerns about VP shunt placement in a child?
The degree of ventricular dilation raises concern about CSF draining too rapidly.
The skull will not collapse as it would in a neonate and hence there is concer about the cortex falling away from the skull because of loss of CSF volume. In this situation the child may be drowsy for some time post surgery or may develop subdural effusions.
Strategies to prevent this include programmable shunt valves or prolonged bed rest afer shunt placement to prevent over drainage due to siphoning effects of shunt tubing
99
A 6-month-old boy presents via the paediatricians with progressively enlarging head
circumference. His head now measures 51.5cm, which makes it far above the 95th
centile (5th to 95th centile range 41.5–46cm). There is no medical history of note; he
was born by ventouse delivery at 38 weeks and is developmentally normal. Examination
finds that there is a bulging fontanelle but no loss of upgaze, and the boy seems alert
and normal apart from his head, which is clearly enlarged.
CT shows ventriculomeggaly 2o to idiopathic hydrocephalus
A VP shunt is placed with a medium–low pressure (70mmH 2 O) valve. The boy
is discharged 2 days later, but is taken to his GP after 3 weeks with progressive irritability,
fluctuating consciousness, and vomiting. His GP suspects that the shunt is
blocked and refers him directly for a CT scan.
What does the CT scan (Fig. 60.2 ) show?
The CT does not suggest that the shunt is blocked as the ventricles are smaller. Rather it suggests that the shunt is working too well, the ventricles ar enow far smaller and there is CSF overlying the cortex on the right side.
There is a large slighlty hypodense collection overlying the left cerebbral hemisphere with midline shift to hte right due to a subdural haematoma.
The shunt catheter is seen within the occipital horn of the right lateral ventricle.
100
A 6-month-old boy presents via the paediatricians with progressively enlarging head
circumference. His head now measures 51.5cm, which makes it far above the 95th
centile (5th to 95th centile range 41.5–46cm). There is no medical history of note; he
was born by ventouse delivery at 38 weeks and is developmentally normal. Examination
finds that there is a bulging fontanelle but no loss of upgaze, and the boy seems alert
and normal apart from his head, which is clearly enlarged.
CT shows ventriculomeggaly 2o to idiopathic hydrocephalus
A VP shunt is placed with a medium–low pressure (70mmH 2 O) valve. The boy
is discharged 2 days later, but is taken to his GP after 3 weeks with progressive irritability,
fluctuating consciousness, and vomiting. His GP suspects that the shunt is
blocked and refers him directly for a CT scan.
How would you treat this patient?
The subdural haematoma has arisen because of the lower ICP and collapse of brain due to over-drainage of ventricular CSF.
Simply draining the SDH will invite it to recur.
There must be a change in hte CSF drainage process. This will involve changin the funciton of the shunt. There are three options:
1. Tie off shunt temproraily with a view to untying it after the SDH has resolved clinically and radiologically.
2. Change the valve for one with a higher opening pressure
3. Change the valve for one with variable opening pressure.
101
A 24-year-old female hairdresser is referred to the clinic. She has noticed a progressive
change in sensation in both her hands, on the right a little more than the left, over the
past 2 years. This has not been particularly intrusive and she has not noticed any functional
impairment and is still working normally. However, about 2 months previously
she burnt her thumb very badly on some curling tongs and did not notice until someone
pointed it out, at which point she attended the emergency department. Severe loss
of pain and temperature sensation was found and her GP subsequently arranged an
MRI scan.
What do the patient’s symptoms represent and what is the differential diagnosis?
She has symptoms of loss of pain and temperature but nofine touch or motor control.
This is a form of dissociated sensory loss due to interruption of the spinothalamic tracts which decussate at the level of entry into the spinal cord.
This is strongly suggestive of a lesion within the spinal cord.
The long history suggests a very slow growing neoplasm or syringomyelia
102
A 24-year-old female hairdresser is referred to the clinic. She has noticed a progressive
change in sensation in both her hands, on the right a little more than the left, over the
past 2 years. This has not been particularly intrusive and she has not noticed any functional
impairment and is still working normally. However, about 2 months previously
she burnt her thumb very badly on some curling tongs and did not notice until someone
pointed it out, at which point she attended the emergency department. Severe loss
of pain and temperature sensation was found and her GP subsequently arranged an
MRI scan.
She undergoes an MRI of her cervical spine (Fig. 61.1 ). What does it show?
The sagittal T2 MRI shows at leas two areas of high signal compatible with fluid in the SC at the mid-cervical level and the cervicothoracic junction. This is syringomyelia.
103
A 24-year-old female hairdresser is referred to the clinic. She has noticed a progressive change in sensation in both her hands, on the right a little more than the left, over the past 2 years. This has not been particularly intrusive and she has not noticed any functional impairment and is still working normally. However, about 2 months previously she burnt her thumb very badly on some curling tongs and did not notice until someone pointed it out, at which point she attended the emergency department. Severe loss of pain and temperature sensation was found and her GP subsequently arranged an MRI scan.
This shows syringomyelia.
How would you investigate her further?
She should have further MRI sequences.
Syringomyelia can be idiopathic but it is more commonly due to an associated abnormality.
She should have an MRI of the entire craniospinal axis, particularly the foramen magnum
104
Pathologies presenting with syringomyelia
Spinal cord tumours (either at the site or remotely)
Hydrocephalus
Tethering of the SC
Chiari malformation
105
A 24-year-old female hairdresser is referred to the clinic. She has noticed a progressive
change in sensation in both her hands, on the right a little more than the left, over the
past 2 years. This has not been particularly intrusive and she has not noticed any functional
impairment and is still working normally. However, about 2 months previously
she burnt her thumb very badly on some curling tongs and did not notice until someone
pointed it out, at which point she attended the emergency department. Severe loss
of pain and temperature sensation was found and her GP subsequently arranged an
MRI scan.
This showed syringomyelia
More scans are done. What is the aetiology of her symptoms?
There is a chiari malformation with cerebellar tonsillar descent through the foramen magnum to the level of the body of C2.
There is not a particulalry vertical cerebellar tentorium or appreciable platybasia. Tonsillar descent in isolation is a feature of the Chiari 1 malformation which usually presents in adulthood with cough headaches.
106
Chiari I malformation
Downward displacement of the medulla and cerebellar tonsils.
Syringomyelia
107
Chiari 2 malformation
(Arnold-Chiari)
Herniation of the cerebellar tonsils
Hydrocephalus
Kink in the medulla
Myelomeningocele
Syringomyelia
108
Chiari 3
Further herniation of the cerebellum below the foramen magnum following an encephalocele in addition to spina bifida
109
Chiari 4
Hypoplasia/aplasia of the cerebellum with spina bifida
110
What are the treatment options for Chiari I malformationw ith syrinx?
If a patient is having symptoms due to the syrinx there is an argument for treating this directly with a syringosubarachnoid shunt.
Routine practice should be to perform a foramen magnum decompression in the first instance to attempt to normalise CSF dynamics around the foramen magnum.
Additionally tonsillar resection may be performed to increase the space around the medulla and SC in the foramen magnum.
The hope is that improving CSF flow around the foramen magnum will help resolve the syringomyelia.
If patient develops worsening syringomyelia despite an adequate foramen magnum decompression, a syringo-subarachnoid shunt may be required.
111
What should patients undergoing foramen magnum decompresison for chiari malformation causing syringomyelia be counselled?
Should be advised of the benign but progressive nature of syringomyelia.
Should be advised that symptoms may not improve despite surgery and therefore that surgery is to halt decline rather than reverse it.
112
What are the risks of foramen magnum decompression
May be continued decline requiring a syringo-subarachnoid shunt
Some patients develop hydrocephalus requiring VP shunt post-oepratively.
Risks of posterior fossa surgery.
Patients are likely to feel very nauseated and dizzy following the surgery though this will gradually settle.
113
What are the risks of posterior fossa surgery?
Persistent CSF leak
Pseudomeningocoele.
114
A 24-year-old female hairdresser is referred to the clinic. She has noticed a progressive
change in sensation in both her hands, on the right a little more than the left, over the
past 2 years. This has not been particularly intrusive and she has not noticed any functional
impairment and is still working normally. However, about 2 months previously
she burnt her thumb very badly on some curling tongs and did not notice until someone
pointed it out, at which point she attended the emergency department. Severe loss
of pain and temperature sensation was found and her GP subsequently arranged an
MRI scan.
MRI shows Chirari I malformation causing syringomyelia.
She undergoes a foramen magnum decompression, C1 and C2 laminectomy,
and tonsillar resection. She recovers from the surgery well and is discharged with
headaches that are improving on day 5. However on day 10 she attends the emergency
department with worsening severe headaches and associated vomiting and
nausea. She has been unable to get out of bed with the headaches and has continuing
neck stiffness. She has a CT scan
What are the salient features?
The foramen magnum decompression is evident (the bony defect created by the operation to decompress the foramen magnum is labelled A.
There is crowding of the enlarged foramen magnum.
There is a left-sided subdural collection. Which is also evident around the cerebellum and the tentorium (B).
There is a little midline shift to the right
115
A 24-year-old female hairdresser is referred to the clinic. She has noticed a progressive
change in sensation in both her hands, on the right a little more than the left, over the
past 2 years. This has not been particularly intrusive and she has not noticed any functional
impairment and is still working normally. However, about 2 months previously
she burnt her thumb very badly on some curling tongs and did not notice until someone
pointed it out, at which point she attended the emergency department. Severe loss
of pain and temperature sensation was found and her GP subsequently arranged an
MRI scan.
MRI shows Chirari I malformation causing syringomyelia.
She undergoes a foramen magnum decompression, C1 and C2 laminectomy,
and tonsillar resection. She recovers from the surgery well and is discharged with
headaches that are improving on day 5. However on day 10 she attends the emergency
department with worsening severe headaches and associated vomiting and
nausea. She has been unable to get out of bed with the headaches and has continuing
neck stiffness. She has a CT scan
What is the diagnosis and management?
There are two possible diagnoses: one is that there has been sufficient brain shift to cause shearing of a briding vein and that this is a subdural haematoma (the most common cause of subdural collection with midline shift).
The collection is very hypodense and isodense with CSF suggesting that it is a subdural effusion caused by low ICP and asymterical brain slump rather than actively pressing the brain to one side.
It would more commonly manifest as bilateral subdural effusions.
This would be supported by the collection being around the tentorium as well.
The likely aetiology is CSF leak into the area of the foramen magnum which usually causes a pseudomeningocoele.
The key feature of the history is the postural variation, if the headaches are worse when she sits or stands they are more in keeping with low CSF pressure.
116
Management of SDH after cranial surgery
Usually burrhole drainage
117
Issues with drainage of subdural collection in context of low CSF pressure after foramen magnum decompression
Will cause brain slump, pneumocephalus and worsening of the patient's neurological condition including drowsiness and even coma.
Patients should be managed supportively with fluids, flat bed rest analgesia.
If patients develop refractory subdural effusions and subdural peritoneal shunt without a valve may be considered
