Increased Intracranial Pressure
Shawn Aylward
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Increased Intracranial Pressure - Abstract
Intracranial hypertension has gone by numerous different terms over the years. Symptoms of intracranial hypertension include headache that can be exacerbated by maneuvers such as Valsalva, bending over or coughing. Other symptoms include nausea, vomiting, diplopia, cranial nerve palsy and tinnitus. The ophthalmic exam is a fundamental part of the diagnosis and management of intracranial hypertension. Direct funduscopic exam of the optic nerves should be performed at each visit. Diagnostic neuroimaging should include MRI and MRV to rule out secondary causes. The largest diagnostic component is the lumbar puncture. Proper positioning includes lateral decubitus with the legs and head extended at the time of measurement. Weight loss (if obese) and acetazolamide are considered the first line treatment for intracranial hypertension. Recurrence is estimated to occur in up to 20% of patients. Development of migraine or other headache syndromes is seen in up to 68% following resolution of their intracranial hypertension.

The original description of intracranial hypertension has been credited to Heinrich Quincke, who pioneered the lumbar puncture. In 1897, he described a series of patients suffering from increased intracranial pressure with normal cerebral spinal fluid (CSF) and labeled this condition “meningitis serosa”.(1) Since Quincke’s initial description, there have been many different names used including serous meningitis, otitic hydrocephalus, toxic hydrocephalus, and hypertensive meningeal hydrops. In 1904, the term “pseudotumor cerebri” was coined by Nonne after similarities in presentation to patients with an intracranial mass.(2) In 1955, Foley suggested “benign intracranial hypertension” to remedy the negative association with a “pseudo-cancer” diagnosis.(3) The term idiopathic intracranial hypertension appeared in the 1980’s following a series of reports describing permanent visual deficits.

Today, pseudotumor cerebri and idiopathic intracranial hypertension remain the most common terminology amongst both practitioners and the lay public. There remains both ambiguity and confusion with both of these terms. There have been recent attempts to clarify the terminology with some using a broader designation of “pseudotumor cerebri syndrome” which still includes the designation of idiopathic when a cause is not found.(4) An easier designation is use of the terms primary intracranial hypertension (PIH) and secondary intracranial hypertension (SIH).(5) The designation of primary would apply when no precipitant that would result in increased pressure is present. Patients may still have risk factors for increased intracranial pressure, such as female gender, post-pubertal status, obesity or polycystic ovarian syndrome, though these conditions do not directly result in increased pressure. SIH is then reserved for instances where the intracranial hypertension is the direct result of another condition, such as cerebral sinus venous thrombosis, or minocycline use.

PIH has traditionally been considered a rare entity. The annual incidence in adults residing in the United States is estimated at 0.9 per 100,000, with no good estimates in the pediatric population.(6) The annual pediatric incidence is estimated at 0.47 and 1.2 per 100,000 in Germany and Croatia respectively.(7, 8) In the provinces of Nova Scotia and Prince Edward Island, the annual incidence was 0.9 per 100,000 in children 2 to 15 years old between 1979 and 1994.(9) Interestingly from 1997 to 2007, the annual incidence fell to 0.6 per 100,000 in children 2 to 16 years, despite increased childhood obesity during this period.(10)

The diagnostic criteria for adult PIH was developed from a series of 22 patients reported by Dandy in 1937.(11) The main limitation of this set of criteria is that imaging of the time was limited to pneumoencephalograms. In 1985, Smith proposed modernization of the criteria into what is now accepted as the modified Dandy criteria to include more current imaging criteria. The criteria stipulate that patients have: 1) signs and symptoms of raised intracranial pressure (headache, nausea, vomiting, transient visual obscurations, or papilledema), 2) absence of localizing neurologic signs with the exception of unilateral or bilateral abducens nerve palsy, 3) CSF opening pressure of >25cm H20 with normal composition, 4) normal to small ventricles as demonstrated by computed tomography (CT) study (today magnetic resonance imaging (MRI)).(12)


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