ESSENTIALS OF DIAGNOSIS
Headache, worse on straining.
Visual obscurations or diplopia may occur.
Examination reveals papilledema.
Abducens palsy is commonly present.
There are many causes of this disorder. Thrombosis of the transverse venous sinus as a complication of otitis media or chronic mastoiditis is one cause, and sagittal sinus thrombosis may lead to a clinically similar picture. Other causes include chronic pulmonary disease, systemic lupus erythematosus, uremia, endocrine disturbances such as hypoparathyroidism, hypothyroidism, or Addison disease, vitamin A toxicity, and the use of tetracycline or oral contraceptives. Cases have also followed withdrawal of corticosteroids after long-term use. In most instances, however, no specific cause can be found, and the disorder remits spontaneously after several months. This idiopathic variety occurs most commonly among overweight women aged 20–44. In all cases, screening for a space-occupying lesion of the brain is important.
Symptoms consist of headache, diplopia, and other visual disturbances due to papilledema and abducens nerve dysfunction. Pulse-synchronous tinnitus may also occur. Examination reveals papilledema (eFigure 24–7) and some enlargement of the blind spots, but patients otherwise look well.
Papilledema from increased intracranial pressure. The optic disk is elevated and hyperemic with engorged retinal veins. The entire optic disk margin is blurred. Optic neuropathies can also have blurring of the entire disk margin but often, only part of the disk is blurred. (From Paul D. Comeau; used, with permission, from Usatine RP, Smith MA, Mayeaux EJ Jr, Chumley H, Tysinger J. The Color Atlas of Family Medicine. McGraw-Hill, 2009.)
Investigations reveal no evidence of a space-occupying lesion. CT or MRI shows small or normal ventricles and an empty sella turcica. MR venography is important in screening for thrombosis of the intracranial venous sinuses. In some cases, stenosis of one or more of the venous sinuses will be observed.
Lumbar puncture confirms the presence of intracranial hypertension, but the cerebrospinal fluid is normal. Laboratory studies help exclude some of the other causes mentioned earlier.
Untreated intracranial hypertension sometimes leads to secondary optic atrophy and permanent visual loss. Acetazolamide (250–500 mg orally three times daily, increasing slowly to a maintenance dose of up to 4000 mg daily, divided two to four times daily) reduces formation of cerebrospinal fluid. Like acetazolamide, the antiepileptic medication topiramate (Table 24–2) is a carbonic anhydrase inhibitor and was shown to be similarly effective in an open label study; topiramate has the added benefit of causing weight loss. Furosemide (20–40 mg daily) may be helpful as adjunct therapy. Corticosteroids (eg, prednisone 60–80 mg daily) are sometimes prescribed, ...