Disorders of Cerebrospinal Fluid Dynamics 2 Flashcards
Which parts of the brain have no blood-brain barrier?
There are four areas of the brain that are not protected by the blood-brain barrier:
- Posterior Pituitary Gland
- Pineal Gland
- Median Eminence of the Hypothalamus
- Area Postrema
These areas are not covered by the blood-brain barrier because they need to secrete hormones into the bloodstream or sense toxins in the blood
Πόσα ml ΕΝΥ παράγονται ημερισίως?
Ο όγκος του ΕΝΥ είναι 150ml
Σε ημερίσια βάση παράγονται 400-500ml
Κατά συνέπεια το ΕΝΥ ανανεώνεται 4-5 φορές σε ένα 24ωρο
Obstructive hydrocephalus: sites of obstruction and examples of causes
Foramina of Monro: a third ventricular colloid cyst or other tumor
aqueduct: congenital or acquired lesions, including mumps ependymitis, hemorrhage, or neoplasm
Foramina of Magendie and Luschka: congenital failure of opening (Dandy-Walker syndrome)
basal cisterns: fibrosing posthemorrhagic or postinflammatory meningitis
Acute obstructive hydrocephalus clinical findings
headache and lethargy progress to coma
There may be papilledema, abducens palsy, hyperactive tendon reflexes, and signs of the causative lesion
Without treatment, brainstem reflexes are lost and death follows circulatory collapse
Normal pressure hydrocephalus: causes, clinical findings
Idiopathic NPH
Secondary NPH is most commonly associated with subarachnoid hemorrhage or meningitis, occurs in any age group, and is associated with impaired CSF resorption.
NPH is associated with a classic triad of cognitive impairment, gait disturbance, and urinary incontinence.
Shunt-responsive NPH is more likely when the gait disturbance appears early on and is more prominent than the cognitive impairment
Normal pressure hydrocephalus: diagnosis, management
● The brain MRI is an essential test in a patient with NPH and demonstrates ventriculomegaly out of proportion to sulcal enlargement and no evidence of CSF flow obstruction.
Features of disproportionately enlarged subarachnoid space hydrocephalus (DESH) suggest a good surgical prognosis.
Extensive white matter disease and cortical atrophy, particularly involving the medial temporal lobe, are unfavorable indicators.
● In patients with clinical and MRI features suggestive of NPH, we use a lumbar tap test to help identify patients likely to respond to shunt placement.
● We suggest ventricular shunting in patients who have clinical and MRI evidence of NPH, a positive test result associated with response to shunting (eg, lumbar tap test), and limited or absent negative prognostic indicators
disproportionately enlarged subarachnoid space hydrocephalus (DESH)
a characteristic feature of NPH
DESH is characterized by:
● Ventriculomegaly
● Tight high-convexity and medial subarachnoid spaces (easiest to visualize on coronal MRI)
● Disproportionate enlargement of the Sylvian fissures
● Focally dilated or entrapped sulci without adjacent cortical atrophy
Spontaneous intracranial hypotension: clinical findings
Postural headache is usually the major manifestation of spontaneous intracranial hypotension. The headache ordinarily develops within two hours, and in most cases within 15 minutes, of sitting or standing. Relief is typically obtained with recumbency, usually within minutes.
Some patients do not have a postural component to the headache at onset; in others, the orthostatic pattern may evolve into a chronic daily headache pattern.
Other symptoms associated with spontaneous intracranial hypotension include nausea, vomiting, neck pain, tinnitus, dizziness, and changes in hearing.
Spontaneous intracranial hypotension diagnosis
Diagnostic criteria:
(A) Any headache fulfilling criterion C
(B) Either or both of the following:
** Low CSF pressure (<60 mmH20)
** Evidence of CSF leakage on imaging
(C) Headache has developed in temporal relation to the low CSF pressure or CSF leakage or has led to its discovery
(D) Not better accounted for by another ICHD-3 diagnosis
Diagnosis
The diagnosis of spontaneous intracranial hypotension is made in patients with headache, typically orthostatic in quality, with or without associated symptoms, and with evidence on imaging of CSF leak or low CSF pressure
Brain and spine MRI
We perform magnetic resonance imaging with gadolinium contrast of the brain and spine as the initial studies for confirming the diagnosis of spontaneous intracranial hypotension.
- Brain MRI is the most sensitive test for identifying spontaneous intracranial hypotension and may show diffuse pachymeningeal enhancement or other findings suggestive of low CSF pressure
- Spinal MRI may show extradural fluid collections, collapse of the dural space, or other evidence suggestive of a CSF leak
Additional imaging studies
We perform additional diagnostic imaging such as MR myelography and radioisotope cisternography when initial brain and spine MRI are abnormal but nondiagnostic and when clinical suspicion for the diagnosis is high despite normal initial imaging.
Role of lumbar puncture
LP may cause a CSF leak and post-dural puncture headache, worsening symptoms and potentially obscuring the diagnosis of spontaneous intracranial hypotension.
We generally reserve diagnostic LP for circumstances when neuroimaging is nondiagnostic or as a part of imaging studies that require dural puncture, such as radioisotope cisternography.
Mnemonic for MRI findings in intracranial hypotension
SEEPS
S: subdural fluid collections
E: enhancement of the pachymeninges
E: engorgement (διόγκωση) of the venous sinuses
P: pituitary hyperemia
S: sagging brain
Spontaneous intracranial hypotension management
https://www.uptodate.com/contents/image?imageKey=NEURO%2F135259&topicKey=NEURO%2F3361&search=intracranial%20hypotension&rank=2~150&source=see_link
Idiopathic intracranial hypertension etiology
Medications:
The evidence linking growth hormone treatment, retinoids, and tetracycline antibiotics is strongest
Other than obesity, the association between other medical conditions and IIH is not proven.
Idiopathic intracranial hypertension clinical findings
A typical presentation of idiopathic intracranial hypertension is that of a female of childbearing age who presents with headaches and is found to have papilledema on funduscopic examination.
Headache characteristics in IIH are variable and nonspecific, but usually include daily occurrence, unusual severity, and a throbbing quality
Papilledema is usually bilateral and symmetric; the severity of papilledema is associated with the risk of permanent visual loss.
Other common features of IIH that are unusual in other primary headache disorders are transient visual obscurations, pulsatile tinnitus, and diplopia (often in the setting of abducens palsy).
Of these, pulse synchronous tinnitus is the most specific for IIH.
Idiopathic intracranial hypertension: diagnosis
Diagnostic criteria of IIH require the presence of each of the following
- Papilledema or sixth (abducens) nerve palsy (unilateral or bilateral)
- Normal neurologic examination, except for papilledema and cranial nerve abnormalities
- Neuroimaging (MRI with and without gadolinium and MRV is preferred) shows normal brain parenchyma without evidence of hydrocephalus, mass, structural lesion, or meningeal enhancement
- Normal CSF composition
- Elevated LP opening pressure
A neuroimaging study is required in patients suspected of having increased intracranial pressure to exclude other causes of elevated intracranial pressure. MRI with and without contrast, including postcontrast MRV, is the imaging study of choice
Lumbar puncture should follow MRI unless a source of elevated intracranial pressure is clearly delineated.
An opening pressure greater than 250 mmH2O taken with the patient lying on his or her side with legs extended confirms elevated intracranial pressure.
Pressures between 200 and 250 mmH2O are considered equivocal and require presence of associated clinical findings like stenosis of the transverse venous sinuses.
Higher upper limits of normal may be considered in overweight patients or those that are sedated.
CSF composition is normal in IIH
Visual field testing is an essential part of the evaluation of patients with IIH and provides a means for following the patient and directing treatment.
Arcuate defects and constriction are commonly found on visual field examinations
MRI findings suggestive of idiopathic intracranial hypertension
MRI findings that suggest, but are not diagnostic for, IIH include
* empty sella
* flattening of the posterior sclera (eye)
* distension of the perioptic subarachnoid space (with or without a tortuous optic nerve)
* transverse venous sinus stenosis
https://radiopaedia.org/cases/idiopathic-intracranial-hypertension-44
Idiopathic intracranial hypertension management
- ONSF = αποσυμπίεση οπτικού νεύρου
