Skull base Flashcards
1
Q
When was the House-Brackmann grading described?
A
1985
2
Q
What is the House-Brackmann grading?
A
1 - normal (score 8/8) 2 - mild dysfunction with slight weakness. Normal symmetry and tone (score 7/8). 3 - moderate dysfunction. Obvious but not disfiguring difference between the two sides. Noticeable synkineses. Complete eye closure with effort. (score 5-6/8) 4 - moderately severe dysfunction. Obvious weakness with disfiguring asymmetric. Incomplete eye closure. (score 3-4/8) 5 - severe dysfunction. Barely perceptible motion. Slight movement of the mouth. (score 1-2/8) 6 - total paralysis. (score 0/8)
3
Q
How did the original House & Brackmann (1985) paper propose standardisation of the grading scale?
A
Measuring the movement of angle of mouth and the eyebrow and comparing to the unaffected side. The difference is based on 2.5 mm gradations. The maximum score is 8 (4 for the mouth and 4 for the eyebrow),
4
Q
How does the vestibular nerve appear during surgery?
A
More gray than the cochlear and facial nerves due to less myelination
5
Q
Where is the endolymphatic sac?
A
Midway between the posterior edge of the IAM and the sigmoid sinus
6
Q
What are the differences between an UMN and LMN facial nerve palsy?
A
In UMN cases the forehead is preserved as this is bilaterally represented and emotional facial expression may be maintained e.g. smiling at a joke
7
Q
What is Gubler-Millard syndrome?
A
Base of pons lesion causing CN7, CN6 and contralateral hemiplegia
8
Q
What is benedikt syndrome?
A
CN3 palsy with red nucleus involvement (coarse intention tremor) and contralateral hemiparesis. Dorsal midbrain lesion.
9
Q
What forms the facial colliculus?
A
Facial fibres passing around the abducens nucleus
10
Q
What is crocodile tear syndrome?
A
Lesions of the facial nerve cause abberent connections in the pterygopalatine ganglion between mastication and lacrimation. Chewing therefore results in lacrimation when eating.
11
Q
What are the segments of the facial nerve?
A
Brainstem
Cisternal
Meatal
Labyrinthine - geniculate ganglion gives off GSPN (dry eye)
Tympanic - nerve to stapedius (hyperacusis)
Mastoid - chorda tympani (loss of taste)
12
Q
What pathway control lacrimation (tearing)?
A
Superior salivary nucleus
Nervus intermedius
GSPN > Vidian
Sphenopalatine ganglion
Zygomatic and lacrimal nerves
Lacrimal gland
13
Q
Which nerve do fibres to the submandibular and sublingual glands run on?
A
Chorda Tympani
14
Q
What is the most likely underlying cause for Bell’s palsy?
A
Viral / Inflammatory / Demyelinating polyneuritis
15
Q
What features may be associated with Bell’s palsy?
A
Follows a distal to proximal pattern with motor loss first then
Facial and retroauricular pain (60%)
Dysgeusia (=altered taste) (60%) = chorda tympani
Hyperacusis (30%) = n to stapedius
Reduced tearing (17%) = GSPN
16
Q
What is the evidence for treatments of Bell’s palsy?
A
In patients with Bell’s palsy, early treatment with prednisolone significantly improves the chances of complete recovery at 3 and 9 months. There is no evidence of a benefit of acyclovir given alone or an additional benefit of acyclovir in combination with prednisolone. NEJM RCT 2007 Sullivan et al.
17
Q
What are the surgical treatment options for facial nerve injury?
A
- Approximation if there is a transection via direct anastomosis or cable graft with sural nerve
- Extracranial anastomosis (CN9/11/12
- Facial suspension
- Tarsorrhaphy
18
Q
What are the two types of hearing loss?
A
Conductive and sensorineural - distinguished using Rinne and Weber’s test
19
Q
What are the Rinne and Weber’s test findings in a normal patient?
A
Weber is central i.e. does not lateralize to one side
Rinne has AC>BC
20
Q
What is a positive Rinne’s test?
A
When AC>BC which is normal. If BC>AC this is a negative finding and suggests conductive hearing loss in that ear.
21
Q
How do you perform Rinne’s test?
A
512 Hz tuning fork on the mastoid bone.
When no longer heard it should be moved to the ear.
If it can then be heard again it is positive.
22
Q
How do you interpret Weber’s tests?
A
A tuning fork in the center of the head does not lateralise if the hearing is normal. It lateralises to the side where there is a conductive hearing loss of the contralateral side if there is a sensorineural hearing loss.
23
Q
Interpret the following:
Webers lateralises to the right
Right Rinne’s is negative (BC>AC)
Left Rinne’s is positive (AC>BC)
A
Right conductive hearing loss
24
Q
Interpret the following:
Webers lateralises to the right
Right Rinne’s is positive (AC>BC)
Left Rinne’s is positive (AC>BC)
A
Left sensorineural hearing loss
25
What is Hitzelberger's sign?
Compression of nervus intermedius by a vestibular schwannoma causing numbness over the posterior aspect of the EAC
26
Which nerves supply the external ear?
Pinna = Greater auricular C2/3
Back of ear = Lesser occipital C2
Anterior and superior ear = Auriculotemporal V3
Posterior inferior EAC and = Auricular branch of vagus (Arnold's nerve)
Posterior inferior EAC = Facial nerve sensory branch via nervus intermedius
27
What causes sensorineural hearing loss?
Sensory - cochlear damage from noise exposure, drugs (gentamicin) and viral labyrinthitis.
Neural - Compression of CN8 in the CP angle
28
What is the mechanism behind caloric testing?
The cold water causes the endolymph to become dense and fall.
This pulls the ipsilateral cupula away from the utricle, reducing the firing and causes nystagmus with the fast component to the contralateral side.
Movement of the cupla towards to the utricle = ampulopetal; Away = ampulofugal.
29
Describe the vestibular pathway
Cupula in each of the semicircular canals \> CN8 \> Vestibular nucleus int he medulla \> CN6 and 3 bilaterally via the MLF and control medial and lateral rectus coordination.
30
How do you interpret tympanometry?
X axis is the static pressure and Y axis is the volume.
A = Normal
B = flattened curve suggestive of an compressible fluid in the middle ear
C = Negative compliance suggesting a negative pressure in the middle ear which occurs with eustachian tube dysfunction
31
What tests help to distinguish conductive and sensorineural hearing loss?
PTA / tymps
Otoacoustic emissions
BSAER
Stapedial reflex out of proportion to PTA suggests neural lesion
32
What is the most reliable indicator of an acoustic neuroma from the BAER?
Increased intraaural latency in wave V. BAER sensitivity is 90%.
33
Names the structures
34
What is the different ionic composition of endolymph and perilymph?
Endolymph has high K+ like intracellular fluid, Perilymph has a higher Na+ like extracellular fluid and CSF
35
How do you use Rinne's and Weber's test to localise hearing loss?
36
What is the modiolus?
The conical central axis of the cochlea
37
What are the PTA findings with noise-injury hearing loss?
Sensorineural hearing loss at 4kHz
38
What genetic condition causes haematuria and high frequency hearing loss?
Alport syndrome
39
Which nerve do vestibular schwannomas arise from?
Superior division of the vestibular nerve (not the cochlear nerve!) from the Obersteiner-Redlich (where oligodendrocytes are replaced by schwann cells) zone ~1cm from where the nerve exits the brainstem.
40
What is the function of schwannomin / merlin?
A tumour suppressor gene involved with cytoskeleton:membrane binding
41
What proportion of VS are unilateral?
95%
42
Which patients should undergo genetic screening for NF2?
Unilateral VS and \<40 years
43
What is the difference between VS from sporadic cases compared to NF2?
Sporadic cases displace the CN8 whilst in NF2 they form grape-like clusters that infiltrate the nerve.
44
What are the histological subtypes of vestibular schwannomas?
Antoni A (narrow elongated bipolar cells) and Antoni B (loose reticulated). Verocay bodies (eosinophilic areas surrounded by spindle shaped schwann cells) are also seen.
45
What is the presenting triad of VS?
Ipsilateral sensorineural hearing loss, Tinnitus and Vertigo.
Large tumours go on to cause brainstem compression (facial numbness \> weakness \> diplopia) / hydrocephalus.
46
What is the cause of hearing loss with VS?
Initially thought to be stretch on the CN8, but new evidence suggests secretion of toxic factors causing cochlear damage
47
What is the hearing loss pattern with VS?
Gradual and insidious. 70% have high-frequency loss causing high pitch tinnitus and word discrimination is affected more.
48
What are the causes sensorineural hearing loss
Tumour, infection, toxin, vascular and autoimmune
49
Why does CN5 palsy occur before CN7 with VS?
As sensory fibres are more vulnerable to compression than motor fibres
50
What is the earliest clinical finding with VS?
SNL hearing loss
51
What are the examination findings in patients with VS?
SNL hearing loss (66%) Loss of corneal reflex (33%) Nystagmus (26%) Facial numbness (26%) Facial weakness (12%) Diplopia (11%) Papilloedema (10%) Babinski sign (5%)
52
Explain the Rinne's and Weber's test with VS?
Weber - tuning fork at vertek \> localises to the contralateral side Rinne's - positive i.e. air\>bone conduction on both sides
53
What is the House-Brackmann grading system (1985)?
1 = normal 2 = mild dysfunction with normal symmetry at rest but slight weakness 3 = moderated dysfunction with non-dyfiguring asymmetry. Complete eye closure with effort. 4 = Moderate to severe dysfunction = dysfiguring asymmetry with incomplete eye closure 5 = Barely perceptible motion 6 = No movement
54
What is the differential diagnosis of a CP angle lesion?
VS Meningioma Schwannoma of an adjacent cranial nerve e.g. CN5 or 7 Arachnoid cyst Epidermoid Metastasis Aneurysm Neurenteric cyst
55
How would you investigate a patient with a CP angle lesion?
MRI +/- contrast with CISS/FIESTA
CT skull base
Audiometry (PTA / Tymps / speech discrimination)
Further ancillary testing if small VS (\<1.5 cm dia) include ENG / VEMP / ABR.
56
Why should you order a thin CT for pre-op VS planning?
Middle fossa - geniculate ganglion position and identify dehsicence
Translab - pneumatisation of the mastoid and position of the sigmoid sinus and jugular bulb (high riding)
Retrosigmoid - Bone coverage over the posterior semicircular canal and pneumatisation of the retro facial region (CSF leak risk). Position of the endolympathic sac.
57
What are the Electronystagmography (ENG)?
Electronystagmography - use to assess superior vestibular nerve function through cold and warm water (bi-thermic caloric testing in the ear causing nystagmus = (COWS) cold opposite warm same) . Note this only tests the horizontal semicircular canal.
58
Interpret this ENG result:
Reduced superior vestibular nerve function in the right ear on cold caloric testing.
59
What are VEMPs?
Vestibular evoked myogenic potentials. Most commonly recorded in SCM. These assess the inferior vestibular nerve through delivery of acoustic energy the saccule and is independent of hearing function so can be performed if completely deaf..
60
What are BAERs?
Brainstem auditory evoked responses. In VS results in prolonged I-III interpeak latencies. Useful for prognostication as poor wave morphology corresponds to lower chance of preserving hearing even with good pre-op hearing.
61
Which patients should be screened for a VS?
\>10dB symmetric sensorineural hearing loss at \>2 frequencies, asymmetric tinnitus (positive yield \<1%!) or sudden sensorineural hearing loss in one ear.
62
What is the audible spectrum?
500-2k Hz
63
What do the X, O and triangles denote on a PTA?
X = Left
O = Right
and Triangle = bone conduction
64
How do you differentiate high freq hearing loss from a VS compared to hearing loss with age or loud noise?
VS hearing loss is asymmetric whilst other causes are symmetric.
Asymmetric sensorineural hearing loss \>10 dB at two consecutive frequencies is indicative of a VS.
65
Which type of hearing loss has most effect on speech discrimination?
Retrocochlear hearing loss (note speech discrimination maintained with conductive hearing loss)
66
How is serviceable hearing defined?
Modified Gardener-Robertson - PTA loss \<50 dB and speech discrimination \>50% serviceable
Pragmatically: 1 = may use a phone on that side, 2 = can localise sound
67
Why are CISS/FIESTA useful for VS workup?
Visualise the course of the facial nerve and surrounding CNs if involved
68
What do hyperintense T2 regions of a VS suggest about the tumour?
That these tumours are softer and suckable so result in better CN VII function.
69
How do you grade the tumour extent of VS?
Using the Koos grading system:
1 = intracanalicular (\<0.5 cc)
2 = Protrusion into CPA (\<1 cc)
3 = Extends to brainstem but does not displace it (\<2 cc)
4 = Displaces the brainstem and cranial nerves (4 cc)
70
What are the management options for VS?
1. Conservative - watchful waiting
2. Radiosurgery - single dose SRS with \<13Gy is recommended for hearing preservation
3. Surgery
4. Biological therapies - Anti-VEGF (Avastin) for NF-2 related VS
71
Which VS have a faster growth rate with conservative management?
Those that expand outside of the IAC
72
Which tumours had a lower hearing preservation rate and high risk of CN7 injury?
\>15 mm diameter
73
Which VS may demonstrate sudden and dramatic growth?
Cystic tumours
74
What are the CNS practice guidelines for the management of Koos 1 VS (intracanalicular) without tinnitus?
Observation - as these have a lower rate of growth and better hearing preservation.
75
What are the hearing preservation rates with SRS?
25-50% @ 10 years for serviceable hearing pre-SRS
76
Is there grade 1 evidence for the management of VS?
No!
77
What is your management algorithm for VS?
Koos 1/2 with intact hearing - conservative and treat only if \>2 mm growth between 6 monthly MRI
Koos 3 - treatment with SRS or surgery
Koos 3/4 - Surgery to reduce the mass effect and decompress the brainstem
78
What is the difference in hearing preservation between SRS and surgery for VS?
At 5 years SRS is better but at 10 years it is the same. The hearing preservation with SRS is dependent on the amount of radiation given to the cochlear. With surgery experience and use of cochlear monitoring improves hearing.
79
What is the rate of facial nerve preservation?
98% overall with Koos 1-2.
With SRS it is also good if 13Gy is given (but not 20Gy)!
80
What is the risk of developing trigeminal neuralgia with SRS for VS?
7% with the higher dose of 20Gy, but no patients developed it if 13Gy was used.
81
What % of SRS treated VS increase in size?
20% show pseudo growth at 8 months, but the retreatment rate at 5 years was 4% (same as surgery)
82
How do you treat vertigo associated with VS?
Self limiting and improves with vestibular rehab exercises
83
Which surgical approaches are best for hearing preservation?
All should be treated by retrosigmoid except ff small and intracanalicular then middle fossa. Note middle fossa has a higher facial nerve palsy risk.
84
Which nerves should be monitored during VS surgery?
CN7 and 8. CN8 monitoring can be direct or via BAERs
85
What is the difference between serviceable and salvageable hearing?
Serviceable = 50/50 rule with PTA \<50dB and \>50% speech discrimination score
Salvageable hearing is whether serviceable hearing will be preserved post-op. This is unlikely if the pre-op speech discriminiation score \<75%, PTA losses at \>25%, tumour \>2 cm or the pre-op BAER are abnormal.
86
Who performed the first VS resection?
First performed by Charles Ballance (NHNN) in 1894
87
Which direction is the facial nerve displaced with VS?
Forwards 75% \>Inferior\>Posterior
88
Where is the cochlear nerve found in VS surgery?
10% as a separate band on the tumour surface
90% within the tumour!
89
What is the goal of VS surgery if the tumour is tightly adherent to the CN7 or brainstem?
Subtotal / near-total resection leaving a small cuff on the nerve followed by SRS
90
How do you treat hydrocephalus associated with a VS?
VP shunt followed by surgery ~2 weeks later or EVD at start of surgery
91
Describe the translabyrinthine approach.
Supine head turn
Prep abdo for fat graft
C-shaped skin incision behind pinna to allow exposure of sigmoid
Mastoidectomy and preserve facial canal
Drill through vestibular apparatus behind and superior to CN7
The dura bounded by the sigmoid sinus, sup. petrosal sinus and deep to the labyrinthine is Trautman's triangle.
Open the dura to get access to the posterior lateral brainstem.
92
Label the anatomy of the pre-sigmoid approach
A- Sinodural angle
B- Trautman's triangle
C- Sigmoid sinus
D- Jugular bulb
E- Facial nerve (mastoid segment / tympanic segment)
F- Semicircular canal
93
How do you open the dura for a translabyrinithine approach?
94
Describe the retrosigmoid approach.
Lateral position - mayfield
Lumbar drain
C-shaped incision 3 cm behind the pinna
Identify asterion and then transverse-sigmoid junction with craniotomy
C- Durotomy with release to angle between transverse-sigmoid junction
Sacrifice the petrosal vein to allow cerebellum to fall away
Exposure to CPA and cisterna magna for CSF release
Identify tumour capsule and perform CN7 monitoring during resection
95
CT anatomy for approaches to VS
Important not to enter the Superior semicircular canal when entering the IAM during a retrosigmoid approach otherwise they will lose hearing. Drill anterior to the endolymphatic canal
96
Describe the middle fossa approach.
Lumbar drain
Head horizontal
6 cm incision starting ant to the tragus
4x3 cm craniotomy
Subtemporal extradural approach - section MMA and preserve the GSPN
Drill and expose the IAM from the meatus to Bill's bar
Localise CN7 with stimulator
Open the dura over the IAM and dissect tumour from CN8
97
What are the routes for CSF leak following VS?
1. Apical to the tympanic cavity (most common)
2. Vestibule of the horizontal semicircular canal
3. Posterior semicircular canal
4. Perilabyrinithine cells \> Mastoid air cells
5. Mastoid air cells during craniotomy
98
Where is the vestibule of the semicircular canal?
Where all of the semicircular canals join. The oval window opens into the vestibule.
99
How do you manage facial nerve dysfunction following VS surgery?
Lacrilube, eye taping at night. If complete loss then tarsorrhaphy within a few days.
Facial reanimation with CN12-CN7 anastamosis 2 months after CN7 nerve was divided.
100
What is attached to the oval window?
The footplate of the stapes. Note: the round window is between the middle and inner ear and covered with a membrane.
101
What is the risk of malignant transformation with SRS for VS?
3 in 1000
102
What is a perineurinoma?
Tumour composed exclusively of neoplastic perineural cells. Causes pseudo-onion bulb formation with cylindrical enlargement of the nerve over 2-10 cm. Can be grade 1-3.
103
What % of MPNST are associated with NF1?
50%. In NF1 they tend to occur in plexiform or intraneural neurofibromas
104
What is the action of Bevacizumab?
VEGF inhibitor
105
What are the boundaries of Trautmann's triangle?
Superior petrosal sinus above
Sigmoid sinus behind
Jugular bulb below
Semicircular canal anterior
106
What are the features of cystic VS?
More rapid growth
Frequent CN7 involvement
Unpredictable biological behaviour
Heamorrhage into the cyst esp after SRS may be associated with brainstem compression and obstructive hydrocephalus
107
Is there any difference in facial nerve palsy rates with approach to VS?
Middle fossa approaches are associate with a higher facial nerve palsy rate, but there is no difference between retrosigmoid and translabyrinthine approaches.
108
What HB grading has the best outcome from facial reanimation therapy?
HB3
Options include face-lift/eyelid tarsorrhaphy
facial anastomosis
109
What is the management of a parasellar meningioma causing visual impairment?
Decompression of the optic nerve
Resection of the extracavernous portion compressing the CN2
SRS to the remainder
110
What is the blood supply to anterior skull base meningiomas?
Ethmoidal arteries
Opthalmic A branches
ACA branches if very large
111
How do you differentiate chordomas and chondrosarcomas?
Indistinguishable on MRI. Classic soap bubble appearance. Chordomas arise from the midline whilst chondrosarcomas arise paramedian.
Chordomas sacral 50%, clival 35% and vertebral 15%
112
What jugular foramen syndromes affect CN9/10/11?
Vernet = 9/10/11
Collet-sicard = 9/10/11/12
Villaret = 9/10/11/12/Sympathetics
113
What are the contents of foramen lacerum?
Carotid
GSPN / Vidian nerve
Ascending pharyngeal artery
Emissary vein
114
What is a transcochlear approach?
Drilling of the superior and posterior EAM
The sacrifice of the semicircular canals and cochlear
Rerouting the facial nerve to access the CPA, petrous apex and ventral brainstem
115
What is the most common pituitary tumour?
Pituitary adenoma
116
How do pituitary tumours present?
Endocrinopathy, mass effect, headache, incidental finding and pituitary apoplexy
117
Which pituitary tumour is managed medically?
Prolactinoma with DA agonists (Cabergoline / bromocriptine / Quinagolide)
118
Pituitary carcinomas are invasive. Which hormones are they likely to secrete?
Prolactin or ACTH
119
What are the most common type of pituitary adenoma?
Non-functioning
120
Which familial syndrome is most commonly related to pituitary adenomas?
MEN1 - Autosomal dominant and also involves pancreatic islet cell tumours and parathyroid tumours. The pituitary adenomas are usually non-secretary.
121
Which hormones are secreted by adenomas?
PRL (48%), GH (10%), ACTH (6%) and TSH (1%)
122
How do prolactinomas present?
In Females - amenorrhoea-galactorrhea syndrome In Males - impotence
123
What is the stalk effect?
Compression of the pituitary stalk results in loss of DA inhibition and a modest rise in prolactin
124
What is the difference between Acromegaly and Gigantism?
Gigantism occurs before the closure of the epiphysis
125
What is thyrotropin?
TSH
126
How do FSH / LH secreting tumours present?
Usually clinically silent. FSH may cause amenorrhea-galactorrhea syndrome due to ovarian hyperstimulation
127
Which hormones are likely to be deficient with pituitary adenomas?
Go Look For The Adenoma GH \> LH \> FSH \> TSH \> ACTH
128
What does chronic panhypopituitarism cause?
Pituitary cachexia AKA Simmond's cachexia - characterised by anorexia, amenorrhea, premature aging and low metabolic rate
129
Selective single pituitary deficiency is rare with adenomas. What other diagnosis should be considered?
Autoimmune hypophysitis which commonly causes deficiency of ACTH or ADH - resulting in DI
130
How does GH deficiency present?
In children with short stature
In adults with muscle loss, centripetal obesity and reduced exercise tolerance
Hypogonadism
131
How does hypothyroidism present?
Weight gain
Hair loss / dry skin
Cold intolerance
Myexdema
Entrapment neuropathy (carpal tunnel)
Tiredness
Constipation
132
What is Woltman's sign o hypothyroidism?
Delayed relaxation of the ankle jerk
133
What conditions are associated with DI at presentation?
Autoimmune hypophysitis
Hypothalamic glioma
Suprasellar GCT
Craniopharyngioma
134
What is Kallmann syndrome?
Combination of anosmia and central hypogonadatrophic hypogonadism. MRI reveals a lack of olfactory bulb in 60%,
135
What are the consequences of mass effect by a pituitary lesion?
Optic chiasm \> bitemporal hemianopsia starting from the upper fields
Thrid ventricle \> obstructive hydrocephalus
Cavernous sinus \> Cranial neuropathy, proptosis, chemosis from venous congestion, encasement of carotids
CSF leak
Headache
136
What is the definition of apoplexy?
Sudden expansion of a sellar mass causing neurological or endocrinological deterioration
137
What causes expansion with apoplexy?
Haemorrhage, necrosis or infarction
138
How does apoplexy present?
Headache
Visual disturbance (opthalmoplegia \> VFD)
Loss of conciousness (raised ICP or hypothalamic involvement)
Cavernous sinus compression (Cranial neuropathy / venous congestion)
139
What is the difference between Cushing's syndrome and disease?
Cushing's syndrome is a constellation of symptoms secondary to hypercortisolism.
Cushing's disease is hypercortisolism secondary to an ACTH-secreting adenoma.
140
What are the causes of endogenous hypercortisolism?
Pituitary adenoma (80%) - mildly elevated ACTH
Ectopic ACTH from lung ca (10%) - very elevated ACTH
Adrenal adenoma / carcinoma (10%) - low ACTH as directly secretes cortisol suppressing ACTH
Hypothalamic CRH release (very rare) - elevated ACTH
141
Which carcinomas can release ectopic ACTH?
Small cell lung ca
Thymoma
Carcinoid tumours
Phaeochromocytomas
Medullary thyroid ca
142
What is the gender predominance of Cushing's disease?
10x more common in women
Note: Ectopic ACTH is 10x more common in men!
143
What is more common, ACTH releaseing adenoma or Acromegaly?
Acromegaly is 4x more common than Cushing's disease
144
What is the difference between the types of pituitary adenomas in adults and children?
Cushing's disease is more frequent in children and non-functioning is less frequent.
145
What size are ACTH-releasing adenomas typically?
\<5 mm in 50% of cases
146
What are the clinical features of Cushing's syndrome?
Hands - easy bruising, hyperpigmentation (if ACTH high), carpal tunnel, thin skin
Arms - prox. myopathy, hypertension, osteoporosis
Face - plethoric facies, hirsuitism, acne, depression, dementia
Body - centripetal obesity, buffalo hump, purple striae
147
What are the laboratory findings with Cushing's disease?
Hyperglycaema, hypokalemic alkalosis, loss of diurnal cortisol variation, inappropriately high or normal ACTH levels, high 24 hours urine free cortisol, failure to suppress with low dose dexamethasone test
148
What is Nelson's syndrome?
Occurs in 30% of patients that undergo bilateral adrenalectomies performed for Cushing's disease which is performed when adenoma is non-resectable or failure of medical therapy after TSH.
Presents with hyperpigmentation (due to ACTH cross reactivity with MSH), high ACTH and progression of pituitary tumour
149
What is the treatment for Nelson's syndrome?
Resection of adenoma, Radiotherapy or Medications e.g. Metyrapone
150
Why does Nelson's syndrome occur after bilateral adrenalectomy?
Cortisol levels normalise \> CRH levels rise \> ACTH-releasing adenoma grows \> high ACTH causes hyperpigmentation due to MSH corss reactivty.
151
Why do you get testicular enlargement with Nelson's syndrome?
Due to high ACTH stimulating hypertrophy of adrenal rest cells in the testes, which then secrete cortisol and in some cases return of Cushing's disease despite adrenalectomy
152
What is the management of pituitary apoplexy?
Hydrocortisone administration
Visual field assessment
Endocrine evaluation
Rapid surgical decompression is required for sudden constriction of the visual fields or deterioration in acuity.
Bills et al 1993 showed in a retrospective study of 37 patients that surgery within 7 days was better then after 7 days.
153
What is the Mod. Hardy's (Wilson) system for classification of pituitary adenoma extension / spread?
**_Extension_**
Suprasellar: A) In suprasellar cistern, B) Recess of 3rd ventricle obliterated, C) Floor of 3rd ventricle grossly displaced
Parasellar: D) Intrdural, E) Into cavernous sinus
**_Spread_**
I - sella \<10mm, II sella \>10mm
III - localised or IV - diffuse destruction of sella floor
V - spread via CSF
154
What is the goal of transsphenoidal surgery in apoplexy?
1. Decompress the optic apparatus, pituitary gland, cavernous sinus and third ventricle if hydrocephalus
2. Histological diagnosis
Complete removal fo the tumour is not necessary
155
What is Forbe's Albright syndrome?
Amenorrhea-Galactorrhea syndrome secondary to prolactin-secreting pituitary tumour
156
What is McCune Albright syndrome?
Polyostotic fibrous dysplasia
Cafe au lait spots
Precocious puberty
157
What % of prolactinomas are microadenomas at diagnosis?
90% in women and 60% in men
158
What % of GH are macroadenomas at diagnosis?
75%
159
What work up is needed for a patient with acromegaly?
Endocrine
Opthalmology
Cardiac (cardiomyopathy)
Colonoscopy
160
What are the criteria for biochemical cure in acromegaly?
Normal IGF-1, GH \<5 ng/ml and GH nadir \< 1 ng/ml after OGTT
161
What are the causes of ectopic GH secretion?
Carcinoid tumours of the lung, pancreas and GI tract
162
What % of GH-adenomas also secrete prolactin?
25%
163
Which genetic syndromes are associated with acromegaly?
MEN-1, McCune Albright, familial acromegaly and Carney complex (PRKAR1A = protein kinase A regulatory subunit 1A)
164
What are the clinical findings associated with acromegaly?
MNEMONIC: STDS ROC A PIMPS BENT GO BAC
Spade-like hands
Tremor
Diabetic testing marks
Sweating
Rings not fitting
Osteoarthritis - Heberden's nodes
Carpal tunnel syndrome
Acanthosis nigricans
Prox. myopathy
Incisor spacing
Macroglossia
Prognathism
Supra-orbital riding
Bossing of frontal bone
Ears enlarged
Nose enlarged
Temporal hemianopia
Goitre
Organomegaly
Bowel cancer
Apnea sleep
Cardiomyopathy
165
Why is life-expectancy reduced with untreated acromegaly?
Diabetes
Hypertension
Cardiovascular risk
Colon cancer
Sleep apnoea
166
What cardiovascular complications occur in acromegaly?
Cardiomyopathy - reduced LV diastolic function, increased LV size, arrhythmias and fibrous hyperplasia of the connective tissue.
Hypertension exacerbates the cardiomyopathic changes
167
What % of adenomas release TSH?
\<1%
168
What is the difference biochemically between primary and secondary hyperthyroidism?
Primary has high T4 and low TSH
Secondary has high T4 and high TSH
169
What are the clinical symptoms of hyperthyroidism?
Anxiety
Palpitations
Atrial fibrillation / SVT
Heat intolerance
Hyperhidrosis
Weight loss despite increased food intake
170
What are the clinical signs with hyperthyroidism?
Hyperactivity, lid lag, tachy, irreg heart rate, hyperreflexia and tremor. Exopthalmos and pretibial myxedema are only with Grave's disease.
171
What are the most common histologies with non-functional adenomas?
Null cell adenomas
Oncocytomas
Silent gonadotrophin / corticotrophin adenomas
172
What is the most common tumours in the posterior pituitary?
METASTASIS due to the rich blood supply
173
What is the acute management of apoplexy?
Pituitary profile
Empirical IV hydrocortisone if signs of addisonian crisis (haemodynamic instability)
VFD when stable.
Urgent TSH within 7 days should be performed if low conscious level or progressive visual field deterioration (not cranial nerve palsy from cavernous sinus compression).
174
Can DI occur with primary adrenal insufficiency?
NO, you cannot diagnose DI unless the adrenal glands are functioning as the mineralocorticoid (aldosterone) is needed to concentrate the urine. Steroids can mask DI as they have mineralocorticoid effect.
175
When are LH & FSH highest?
Mid-cycle
(FSH follicular 0.5-5, mid-cycle 8-33 and luteal 2-8)
(LH follicular 3-12, mid-cycle 20-80 and luteal 3-16)
176
What is a predictor of hypopituitarism following apoplexy?
Low prolactin levels
177
When do you check morning cortisol after transsphenoidal surgery?
Check 9 am cortisol on day 2 or 3 (omit the evening dose of hydrocortisone the night before).
If \>550 nmol/l then does not need steroids
If 400-550 nmol/l then needs steroids when ill
If \<400 nmol/l then commence steroid replacement
All hormones should be rechecked at 4-8 weeks
178
How does the water deprivation test distinguish cranial and nephrogenic DI?
Serum osmo \>290 i.e. becomes dry with water deprivation
If urine osmo fails to concentrate i.e. \<300, but the administration of DDAVP does lead to urine concentration then this is a cranial cause i.e. lack of ADH release. If the DDAVP does not lead to urine concentration then this is a nephrogenic cause of DI as the kidney is unable to contrate the urine.
179
What test should you perform in a patient with synchronous germinoma?
Serum and CSF B-HCG and AFP (as there may be non-germinomatous elements)
180
How are BAERs performed?
An ear plug is placed in the ipsilateral EAC and clicking sounds are delivered.
A needle electrode is placed anterior to the tragus (anode) and at the vertex (cathode).
7 waves are generated within 10 ms of the click. Only the first 5 waves (ECOLI) are used clinically. Wave V is the most sensitive and any change in latency of V \>0.5 seconds is indicative of disturbance.
181
What is a normal response to a short synacthen test?
Levels should be \>600 nmol/l after 30 mins otherwise the patient has primary adrenal insufficiency!
182
Which hormone is most likely to be deficient in non-functioning adenomas?
FSH/LH
183
What is a contraindication to GH therapy?
Active malignancy
184
What is the gold-standard test for GH deficiency?
If **IGF-1 level** is low then dynamic testing with **insulin tolerance test** is required. This is contraindicated in those with IHD, epilepsy and obesity. In which case stimulation testing with **GHRH-arginine test** is needed.
185
What prolactin levels are associated with a stalk effect vs a prolactinoma?
Normal levels are \<100 ng/l or \<2000 mIU/l
Stalk effect levels are \<200 ng/l or \<4000 mIU/l
Prolactinoma level are \>200 ng/l or \>4000 mIU/l
186
How do you treat a non-functional pituitary adenoma with significant cavernous sinus invasion?
TSH to debulk the lesion and decompress the optic nerves
Ensure enough distance between the tumour and the optic nerves so that SRS can be given to the cavernous sinus residual tumour.
187
Why does hypothyroidism result in raised prolactin levels?
As prolactin release is stimulated by high levels of TRH (which is elevated in hypothyroidism)
188
Why should females starting bromocriptine/cabergoline also commence oral contraceptives?
As they will normalise the prolactin levels and restore fertility
189
Why is the management of prolactinomas challenging during pregnancy?
As prolactin levels are unreliable.
Growth during pregnancy is 5% for micros and 15-40% for macros
190
What is the significance of a hypointense area in the pituitary gland in a patient with Cushing's syndrome?
This is a nonspecific finding that is also seen in 10% of normal patients. so IPSS should be performed to rule out ectopic ACTH secretion from a carcinoid tumour in the lung, adrenal or GI systems.
191
What are the risks of untreated Cushing's disease?
Cardiovascular events
Obesity
Infections etc
5x higher mortality with Cushing's disease which is reversed with treatment.
192
What are the options after failed TSH in Cushing's disease?
Hemihypophysectomy or completion hypophysectomy
Medical treatments (metyrapone, ketoconazole, mitotane and etomidate)
Glucorticoid-R blocker (mifepristone)
Bilateral adrenalectomy (risk of Nelson's syndrome)
193
How do you diagnose Acromegaly?
Raised IGF-1
If unequivocal then needs an OGTT. If it fails to suppress GH to \<1ng/ml then confirms GH-releasing adenoma.
194
What are the boundaries of Trautmann's triangle?
Superior petrosal sinus above
Sigmoid sinus behind
Jugular bulb below
Semicircular canal anterior
195
What is the initial management of a patient with a CSF leak after TSH?
CT head to r/o hydrocephalus and subdurals
Abx if signs of meningitis
Flat bed rest (spontaneous resolution in 70%)
If fails to resolve spontaneously then lumbar drain +/- re-exploration.
If defect \<1cm - fat plug
If larger needs cartilage graft / nasoseptal flap
196
What are the MRI features of a Rathke's cleft cyst?
T1 hyperintense cyst due to the proteinaceous content of the cyst fluid. Thin uniform wall which does not enhance.
197
What are the features of cystic VS?
More rapid growth
Frequent CN7 involvement
Unpredictable biological behaviour
Heamorrhage into the cyst esp after SRS may be associated with brainstem compression and obstructive hydrocephalus
198
What is a marginal sinus?
A sinus that runs on the inner aspect of the foramen magnum
199
What SRS dose is given to vestibular schwannomas?
12Gy. Not 16 Gy is associated with facial nerve injury in 1/3!
200
How do you perform a directed examination of the pituitary gland?
Endocrine hyperfunction (prolactin = amenorrhea / galactorrhea; thyroid = heat intolerance sweating etc; GH = acromegaly features; cortisol = cushing's disease and hyperpigmentation) Endocrine loss of function (hypothyroid, addisons etc) Visual dysfunction (bitemporal hemianopia) Cavernous sinus defect (cranial nerve defects causing opthalmoplegia, proptosis and chemosis)
201
What investigations would you perform in a patient with a suspected pituitary lesion?
Endocrine (8 am cortisol and 24 h urine free cortisol, prolactin, FSH/LH, testosterone (M) and oestradiol (F), IGF-1 and fasting glucose, T4 and TSH). Visual fields - Humphrey perimetry MRI +/- contrast pituitary
202
Why do you perform both 8am cortisol and 24h urine free cortisol testing?
8 am cortisol if best to detect pituitary insufficiency 24h urine free cortisol if best to detect Cushing's disease
203
What is the other name for IGF-1?
Somatomedin-C
204
What are the ways the visual fields can be tested?
Humphrey automated perimetry \> Visual evoked potentials \> OCT (document extent of damage to the optic disc)
205
What does red light detection loss signify?
Desaturation of light is an early sign of chiasmal compression
206
What is more common, a pre- or post-fixed chiasm?
Pre (8%) and post (4%). The rest are directly above the sella!
207
What visual field loss is associated with a pituitary adenoma?
Bitemporal hemianopsia! If post-fixed then can have unilateral visual loss with junctional scotoma (pie in the sky) in the contralateral eye due to compression of Willbrand's knee. If pre-fixed then may have homonymous hemianopia from compression of the ipsilateral optic tract.
208
Which hormones should be replaced pre-op if found to be deficient?
Hydrocortisone and T4. Replaced hydrocortisone first otherwise the T4 may precipitate an Addisonian crisis.
209
How does autoimmune hypophysitis present?
Single hormone loss and thickening of the pituitary stalk
210
What does an 8AM cortisol \<6 mcg/100 ml suggest?
Adrenal insufficiency.
211
How is the diagnosis of Cushing's disease made?
Urine 24 h free cortisol \>3 times the upper limit of normal.
False positives with stress and chronic alcoholism.
212
What further tests would you perform is T4 is low and TSH low?
TRH stimulation test.
Check baseline TSH, give TRH 500 mcg then check TSH after 30 and 60 mins.
If the TSH has not doubled by 30 mins then suggests pituitary thyroid deficiency. If TSH goes very high then suggest primary hypothyroidism
213
How do you assess the gonadal axis?
FSH & LH as well as Testosterone (M) and estradiol (F).
214
What does a Prolactin level \>200 ng/ml suggest?
Macroadenoma
215
When should prolactin levels be measured?
Mid-morning and not after stress which may falsely elevate it.
216
What is the only pituitary hormone primarily under inhibitory control?
Prolactin (inhibited by Dopamine)
217
What is the treatment of a raised Prolactin due to a stalk effect?
Remove the compression. Don't start Bromocriptine!
218
What is the Hook effect?
When the prolactin level saturates the assay resulting in a falsely low result. Requires the lab to run serial dilutions.
219
What is macroprolactinaemia?
When the prolactin is bound to Ig and is biochemically non-functional
220
How do you test for DI?
The concentration of urine with water deprivation test.
Further tests include measurement of ADH in response to infusion of hypertonic saline.
221
Why does chronic primary hypothyroidism cause pituitary hyperplasia?
As the pituitary grows in response to a high TRH and TSH due to a lack of T4 negative feedback. A low/normal T4 with high TSH suggest primary hypothyroidism (i.e. problem with the thyroid gland).
222
Why do non-functioning pituitary adenomas cause secondary hypothyroidism?
Mass effect. T4 and TSH are low. There is a reduced response to TRH stimulation.
223
What causes:
1. High TSH and High T4
2. Low TSH and High T4
1. Secondary hyperthyroidism
2. Primary hyperthyroidism
224
What are the causes of a high prolactin?
Pregnancy / lactation
Adenoma
Stalk effect
Drugs (metaclopramide / OCP / TCA / SSRIs / Verapamil etc)
Primary hypothyroidism
Empty sella syndrome
Ectopic secretion
Macroprolactinaemia
Renal / liver failure
225
Which disease causes the ACTH response to CRH to be exaggerated?
Cushing's syndrome
226
What tests would you perform if the 24h urine free cortisol was unequivocal?
1. Low dose Dexamethasone suppression test (give 1 mg Dex at 11 pm and measure cortisol at 8am). If the cortisol suppresses to \<1.8 mcg/dl then Cushing's syndrome is ruled out.
2. 11 pm salivary cortisol (should be at its lowest point)
227
How do you differentiate Cushing's disease from ectopic ACTH secretion?
High dose Dexamethasone suppression test (give 8 mg at 11 pm and measure plasma cortisol at 8 AM).
In 95% of Cushing's disease the ACTH level reduced by 50%. In ectopic causes, it does not suppress.
CT CAP
Metyrapone test - causes a rise in 11-deoxycortisol with Cushing's disease
CRH stimulation test - causes a rise in ACTH and cortisol with Cushing's disease but not with exogenous source
IPSS (baseline to peripheral ACTH \>1.4:1 is consistent with Cushing's disease)
228
How is an IPSS performed?
Catheter placed in the IPSS and ACTH levels are measured at baseline and following CRH at 2, 5 and 10 minutes. Comparison between both sides may help lateralisation. Can lead to false lateralisation due to communication throught the intercavernous sinus.
229
What is the compication rate of IPSS?
2% including puncture of the sinus wall
230
How do you assess for Addison's disease?
ACTH stimulation test (synacthin test) if 8am cortisol is low.
Measure baseline cortisol, given 250 mcg synacthin and then measure cortisol at 60 mins. If cortisol \>20 mcg/dl then rules out Addisons. If \<20 need steroid replacement.
If unequivocal then need to do insulin tolerance test. Insulin given to reduce the BM\<4 and then measure cortisol. If \<20 then need steroid replacement.
231
How can Acromegaly be diagnosed?
IGF-1 level
Oral glucose tolerant test - 75 mg glucose given an GH levels measured every 30 mins for 2 hours. The GH level should fall to \<1 ng/ml in normal cases.
Octreotide SPECT scan for diagnosis of ectopic GH secretion
232
What is the normal size of the pituitary gland?
\<9 mm (or \<11 mm in females of childbearing age / puberity)
233
What MRI should be requested for suspected pituitary adenomas?
Dedicated 3T MRI of the pituitary +/- contrast
If microadenoma then a dynamic MRI allows enhancement to be differentiated from the rest of the gland. Normally the gland enhances before the adenoma.
234
Why does the posterior pituitary have high T1 signal (bright spot) without contrast?
High phospholipid content
235
What does absence of the pituitary bright spot on T1 MRI suggest?
Corresponds with DI due to autoimmune hypophysitis
236
What is the cause of a thickened pituitary stalk?
Lymphoma
Autoimmune hypophysitis
Granulomatous disease
Hypothalamic glioma
\*\*note pituitary stalk is approx the same diameter as the basilar artery
237
Why is a CT performed prior to transphenoidal surgery?
To demonstrate the nasal / sphenoid septal anatomy
238
Should you treat hypothyroidism in a patient with pituitary adenoma?
Check for adrenal insufficiency first with synacthen test. Treat adrenal insufficiency first before giving thyroxine.
239
How should you treat GH secreting tumours before surgery?
Somatostatin analogue before surgery to reduce the surgical risks (general and cardiac).
Then transphenoidal surgery.
240
What is the recommended treatment for symptomatic non-functioning adenomas?
Surgery
Bromocriptine + octreotide may reduce size in 60% of cases
Radiotherapy is an effective adjunct for recurrent or residual disease
\*\*Observation is only recommended for asymptomatic non-functioning adenomas
241
What are the indications for surgery on a pituitary adenoma?
Mass effect
Endocrinopathy
Apoplexy
Diagnosis
Nelson's syndrome (30% of cases of bilateral adrenalectomy develop high ACTH levels which causes pigmentation and enlargement of the pituitary adenoma)
242
What are the side effects of Bromocriptine / Cabergoline?
Postural hypotension, dizziness, depression, nightmares and nasal congestion. Improved by bedtime dosing.
Starting bromocriptine can restore fertility but is teratogenic and can lead to spontaneous abortions.
243
What is the difference between Cabergoline and Bromocriptine?
Bromocriptine is D1 and D2-agonist, whilst cabergoline is D2 only. The half life is longer with cabergoline so once weekly dosing.
244
What side effect is associated with Cabergoline?
Cardiac valvular disease due to effect on fibromyoblasts which causes regurgitation due to valvular fibroplasia.
245
How do you manage elderly patients with asymptomatic GH releasing adenomas?
Conservative
246
How long do IGF-1 levels take to normalise after GH adenoma surgery?
Months. There is no defintion of a biochemical cure. Repeat surgery is usually not successful so medical therapy and radiotherapy may be needed as second-line.
247
What are the medical management options for GH-adenomas?
Somatostatin analogues e.g. octreotide
GH antagonists - pegvisomant
248
What are the side effects of octreotide?
Gallstones
Bradycardia
Diarrhoea / abdominal discomfort
249
What is pegvisomant?
Genetically engineered GH-R antagonist
250
What is the management of Cushing's disease?
SURGERY if microadenoma is visible.
If not, then IPSS. Surgery on the side suggested by IPSS.
If IPSS is negative then look for ectopic source.
251
What is the management if surgery for cushing's disease is unsuccessful?
1. Re-exploration / Completion hypophysectomy
2. SRS if residual cannot be resected e.g. in cavernous sinus
3. Medical therapy
4. Bilateral adrenalectomy
252
What is the difference between a low and high dose Dexamethasone test?
Low dose will only suppress cortisol from a normal gland not an adenoma. Suppression with low dose Dexamethasone rules out a CD.
High dose will suppress an adenoma but not an ectopic source.
253
What are the medical treatment options for Cushing's disease?
Ketaconazole - blocks adrenal steriod synthesis
Aminoglutethimide - prevents cholesterol to pregnenolone
Metyrapone - inhibits 11-beta hydroxylase preventing 11-deoxycortisol to cortisol
Mitotane - inhibits multiple steps in steroid synthesis
Ciproheptadine - seratonin-R antagonist
254
What is the management for pituitary adenomas secreting TSH?
Surgery
Radiotherapy to residual
Medical therapy = octreotide. Causes tumour shrinkage in 1/3,
255
What is the side-effect of radiotherapy to pituitary adenomas?
50% are panhypopituitary at 10 years.
May cause blindness due to optic nerve / chiasm injury
Mental / cognitive disturbance
Cranial nerve palsies
Apoplexy
256
How long does radiotherapy take to work for acromegaly and Cushings?
10-20 years for Acromegaly and 1-2 years for Cushing's
257
When should stress doses be given to patients with pituitary adenomas?
During and immediately after surgery
258
How should you reverse hypothyroidism pre-operatively?
Check HPA axis. Replace cortisol before T4. Replace T4 for \>4 weeks prior to surgery ideally
259
When is a transcranial pituitary resection required over a transphenoidal?
When there is extrasellar extension into the middle fossa or residual inaccessible tumour following transphenoidal surgery
260
What are the transcranial routes to the pituitary?
Subfrontal - prechiasmal (better if chiasm post-fixed) Pterional - optico-carotid triangle
261
Anatomy of the subfrontal route to the pituitary gland
262
Anatomy of the subfrontal route to the pituitary gland
263
What are the transcranial routes to the pituitary?
Subfrontal - prechiasmal (better if chiasm post-fixed) Pterional - optico-carotid triangle
264
How do manage carotid injury during TSPH?
Signalled by profuse arterial bleeding
Pack off with surgicel/muslin
Inform anaesthetist
Stop operation
DSA to identify a pseudoaneurysm
265
Steps of a TSPH
Supine / Mayfield / Neuronavigation
Elevate head 15 deg
Prep thigh for fat graft
C-arm lateral fluoro if not using neuronavigation
Direct (endoscopic) or Indirect (microscopic) approach to sphenoid
Midline opening of sella with drill and expand with rongeur (avoid opening into carotid)
X-opening of dura with #11 scalpel
Use ring cureetes to deliver tumour and remove with rongeur/aspirate
Deliver suprasellar component with valsalva or injecting saline into lumbar drain
After debulk of tumour dissect margins
266
Where is the sphenoid ostium?
At the back of the middle turbinate
267
Where is the sphenoid ostium?
At the back of the middle turbinate
268
How do you perform a TSPH for Cushing's disease without lesion on MRI?
Paramedian incision and exploration on the side with highest ACTH on IPSS. If negative then paramedian incision on the contralateral side then a midline incision. If no tumoru can eb identified then perform a hemihypophysectomy on the sied with highest ACTH.
Note adenomas are usually soft purple/gray whilst the normal fland is pink and firm.
269
How do you close the sella defect after TSPH?
Fat graft
Fascial covering
Gasket closure with implant or septal cartilage
Fibrin glue
Nasoseptal flap
270
How do you close the sella defect after TSPH?
Fat graft
Fascial covering
Gasket closure with implant or septal cartilage
Fibrin glue
Nasoseptal flap
271
What hormonal complications may occur after TSPH?
DI (triple phase response = DI 24 hours, normalisation / siADH, DI long-term)
Addisonian crisis
Long-term hypopituitarism (TSH/ACTH/FSH/LH deficiency)
272
What is secondary empty sella syndrome?
The chiasm retracts into the evacuated sella causing visual impairment
273
Where is the blood supply to the chiasm?
From the ophthalmic A and sup. hypophyseal A which lie below the chiasm. Disrupting this whilst removing tumour may worsen vision.
274
What are the post-operative consideration following TSPH?
1. Fluid balance - perform urine specific gravity, serum and urine osmos and repeat Na daily or if the UO\>250ml/h for 2 hours
2. Antibiotics until removal of nasal packs on day 3-6
3. Stress steroid administration
\*\*Do not allow drinking through a straw to avoid negative pressure causing a CSF leak
275
What are the action sites of medical therapies for Cushing's disease?
Metyrapone inhibits 11-beta-hydroxylase
Ketaconazole inhibits 17-alpha-hydroxylase
Mitotane and etomidate inhibit desmolase
276
What are the action sites of medical therapies for Cushing's disease?
Metyrapone inhibits 11-beta-hydroxylase
Ketaconazole inhibits 17-alpha-hydroxylase
Mitotane and etomidate inhibit desmolase
277
How do you manage DI post TSPH?
Replace losses PO or IV
If losses \>400 ml/h x2 hours then send serum/urine osmolarities, urine SG and Na. If urine SG \<1.003 then consider Desmopressin but be cautious about the triple-phase response.
278
Why does the DI triple phase response occur?
Transient DI following surgery 12-36 hours due to post. pituitary injury
Normalisation / SIADH picture due to release of cells once they die
Long-term DI as no more cells to produce the ADH
279
How do you manage steroid dosing post-TSPH?
Continue stress dosing for 48 hours. Stop the hydrocortisone for 24 hours then measure morning serum cortisol.
If morning cortisol \>9 mcg/dl then normal.
If \<9 mcg/dl then restart hydrocortisone and refer to endocrinology for assessment of ACTH reserve by undertaking short-synacthen test at 1 month. Note: in ACTH deficiency there is adrenal atrophy and becomes unresponsive to the synacthen so will not peak at \>18 mcg/dl which is a normal response.
280
What is the metyrapone test?
This is performed to assess the pituitary ACTH reserve. A synacthen test should be performed first to rule out primary adrenal insufficiency.
Metyrapone is an 11b-hydroxylase inhibitor and reduces cortisol production and subsequently increases upstream metabolites such as 11-Deoxycortisol.
Given 2-3 gram at midnight and measure serum 11-Deoxycortisol in the morning. If there is limited ACTH reserve the adrenals will be atrophied and the total 11-Deoxycortisol levels will be low.
281
What % of pituitary tumours recur?
10%
282
How do you monitor patients following TSPH?
MRI
Endocrine follow up at day 2, 6 weeks and 12 months and Na on day 2 and 7
Opthalmology f/u
283
What treatment is given to residual adenomas secreting TSH?
Radiation
284
What is the definition of cure with Cushing's disease?
\<50 mcg/l (but may be too stringent!)
If \>50 then re-exploration may be advised.
Low dose Dexamethasone test is predictive of remission following surgery.
If you stop the steroids for 24 hours then 24-hour urinary free cortisol is helpful in determining cure rates/
285
What are the outcomes for TSPH in acromegaly?
85% cure with adenomas \<10 mm
(50% overall).
Patients not cured require life-long medical therapy. The greater the debulk the better the response to medical therapy!
286
How do you assess cure for GH secreting tumours?
Oral glucose tolerance test (GH levels should suppress to \<1ng/ml if cured).
287
What are the post-operative consideration following TSPH?
1. Fluid balance - perform urine specific gravity, serum and urine osmos and repeat Na daily or if the UO\>250ml/h for 2 hours
2. Antibiotics until removal of nasal packs on day 3-6
3. Stress steroid administration
\*\*Do not allow drinking through a straw to avoid negative pressure causing a CSF leak
288
Where is the blood supply to the chiasm?
From the ophthalmic A and sup. hypophyseal A which lie below the chiasm. Disrupting this whilst removing tumour may worsen vision.
289
What is secondary empty sella syndrome?
The chiasm retracts into the evacuated sella causing visual impairment
290
What hormonal complications may occur after TSPH?
DI (triple phase response = DI 24 hours, normalisation / siADH, DI long-term)
Addisonian crisis
Long-term hypopituitarism (TSH/ACTH/FSH/LH deficiency)
291
How do you perform a TSPH for Cushing's disease without lesion on MRI?
Paramedian incision and exploration on the side with highest ACTH on IPSS. If negative then paramedian incision on the contralateral side then a midline incision. If no tumoru can eb identified then perform a hemihypophysectomy on the sied with highest ACTH.
Note adenomas are usually soft purple/gray whilst the normal fland is pink and firm.
292
How do manage carotid injury during TSPH?
Signalled by profuse arterial bleeding
Pack off with surgicel/muslin
Inform anaesthetist
Stop operation
DSA to identify a pseudoaneurysm
293
When is a transcranial pituitary resection required over a transphenoidal?
When there is extrasellar extension into the middle fossa or residual inaccessible tumour following transphenoidal surgery
294
How should you reverse hypothyroidism pre-operatively?
Check HPA axis. Replace cortisol before T4. Replace T4 for \>4 weeks prior to surgery ideally
295
When should stress doses be given to patients with pituitary adenomas?
During and immediately after surgery
296
What are the anaesthetic concerns when performing facial nerve monitoring?
No inhalational anesthetics or NMJ blockers (short-acting only)
297
What muscles are recorded from with facial nerve monitoring?
Orbicularis oculi and orbicularis oris.
In addition to intermittent direct electrical stimulation, free-running EMG is also performed.
298
What is the natural history of VS?
The growth of VS is variable but on average growth is around 2-4 mm/year. Cystic VS have the propensity to grow acutely as the cystic component may enlarge.
299
How is speech discrimination tested?
Recordings of words are played to the patient.
The intensity level at which 50% of the words are accurately repeated is the "Speech reception threshold" and correlates with the PTA. Testing uses bisyllabic words (baseball etc)
Speech discrimination is tested using monosyllabic words presented at 40dB above the SRT. 50 words are presented and the % correct is noted.
300
What is the acoustic (stapedial) reflex?
When noise is provided in one ear, both stapedial muscles will contract in normal circumstances. The frequency which this occurs in the threshold. This reflex arc tests the cochlear\>CN8\>brainstem\>CN7\>stapedial muscle contraction. Testing is done ipsilateral and contralateral so the location of the damage in the reflex can be identified. In VS the ipsilateral stapedial reflex is missing when sound is applied to the ipsilateral ear. Sound in the contralateral will make the ipsilateral stapedial muscle contract unless there is CN7 involvement.
301
What questions do you ask to determine the anatomical site of facial nerve dysfunction?
Dry eye = prox to geniculate ganglion
Hyperacusis = prox to nerve to stapedius
Loss of taste = prox to cauda tympani
None of the above present = distal to cauda tympani
302
Endonasal view for direct transphenoidal approach.
303
What is the VS control rate with SRS?
\>90%
