Increased Intracranial Pressure

Shawn Aylward
Increased Intracranial Pressure - Outcome
Pain and permanent vision loss are the two major risks associated with intracranial hypertension, and both have an impact on quality of life.(41, 42) Headache is typically the first symptom to resolve within the first few weeks following treatment initiation followed by papilledema over the subsequent 4-5 months. Post-pubertal status has been found to result in a worse visual outcome in one study.(43) Another study found grade 3 or higher papilledema was a more predictive marker of visual deficits following resolution.(44)

Recurrence is estimated to occur in up to 20% of patients.(45, 46) Ko et al. followed a series of adult patients for recurrence, defined as return of optic nerve edema.(36) In those with recurrence, BMI was an average of 5.5% higher than at initial diagnosis. Those without recurrence had an average of 17.9% weight loss from diagnosis through the follow-up period. Interestingly, the average BMI in those without recurrence was greater than those with recurrence, suggesting weight gain is the major contributor not the actual weight.

Once a patient’s intracranial hypertension has resolved, up to 68% report developing a new or chronic headache type that is different from their intracranial hypertension headache.(47, 48) The most frequent diagnosis is episodic tension type headache or migraine without aura. Fortunately these headache types respond to the typical migraine prophylactic medications.

Whenever possible, a multidisciplinary team should follow a patient with intracranial hypertension. This team should consist of at least a neurologist and ophthalmologist. Neurosurgery, nutrition, physical therapy, psychology, hematology, and/or endocrinology should be included if warranted.
Post-pubertal patients often report recent weight gain over the 6-12 months preceding diagnosis. Numerous adult studies have shown improvements in symptoms and intracranial pressure through weight loss alone.(35, 36) In one of the initial studies, patients were treated with a low calorie and sodium rice diet.(35) None received medications commonly used to treat intracranial hypertension. Weight loss ranged from 11-56 Kg, with resolution of papilledema and the 2 symptomatic patients had complete symptom resolution.

Acetazolamide is considered the first line treatment for intracranial hypertension. The primary method of action is carbonic anhydrase inhibition and resulting decreased CSF production. In children doses of 25-100mg/kg/day (maximum 2 gm/day) divided BID can be tolerated.(37) Typical adolescent dosing is 1 - 2g divided BID. Doses above 2 grams show questionable benefit at the risk of more side effects. Patients often complain of food having a metallic taste to it, especially carbonated beverages, often resulting in transient anorexia.

Furosemide works through diuresis resulting in reduced sodium transport into the brain. The usual dose is 1-2mg/kg/day divided BID/TID.(37) Due to diuretic effect, serum electrolytes must be monitored and potassium supplementation given as needed. This is the main reason it is second line therapy in pediatric patients. Studies do suggest a synergistic effect when used in conjunction with acetazolamide.(38)

Topiramate has weak carbonic anhydrase inhibition properties, making its mode of action similar to that of acetazolamide. An open label treatment study randomized cases with mild papilledema to treatment with either Acetazolamide or topiramate. Using visual field grades to assess for improvement, they found statistically significant improvement amongst both groups suggesting it is a viable alternative.(39)
Corticosteroids used to be a mainstay of treatment for PIH, use has diminished with the discovery of other medication options with fewer side effects. Use of steroids with Acetazolamide has been shown to improve the outcome in cases with severe visual deficits at the time of presentation. Dose recommendations are largely anecdotal and are typically the same used for other inflammatory neurologic disorders such as optic neuritis. A typical course involves intravenous Methylprednisolone 20mg/kg (maximum 1gm) daily for 5 days followed by an oral taper.
Surgical intervention is reserved for patients in whom papilledema or pain persists despite maximum medical care, cannot tolerate medical therapy, or optic nerves are severely swollen at presentation with concern for permanent vision loss.
In general, optic nerve sheath fenestration (ONSF) is utilized to prevent further optic nerve injury by redirecting pressure away from the optic nerve head, but does not effectively lower ICP by itself. Risks include ischemic optic neuropathy, transient blindness, pupillary mydriasis and retrobulbar hemorrhage. Interestingly it has been demonstrated that unilateral fenestration can offer protection with improvements in the un-fenestrated eye. Caution should be used with ONSF in the acute presentation period, particularly in those with signs of ischemia, as the severe swelling and ischemia increases the risk of post-operative ischemic optic neuropathy.
CSF diversion is more effective in those with pain as the primary symptom, though it can be used to protect a patient’s vision in the acute period. There remains some debate even amongst neurosurgeons about whether lumbar or ventricular diversion is superior. Abubaker et al. compared outcomes for 25 patients shunted for management of their intracranial hypertension. They found a failure rate of 11% and 14% and revision rate of 60% and 30% for LP and VP shunts respectively.(40)

Increased Intracranial Pressure Increased Intracranial Pressure 04/20/2016
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