Internal Medicine

0521779407-10 CUNY1086/Karliner 0 521 77940 7 June 6, 2007 17:44

854 Intracranial Hypertension Intracranial Hypotension

■Spinal tap should not be undertaken prior to imaging study; reveals

increased ICP & may suggest cause (eg, SAH, meningitis) if not evi-

dent on MRI

differential diagnosis

■All causes of increased ICP must be considered & excluded by tests

■MRI identifies, localizes & often characterizes structural lesions

■For pseudotumor cerebri, search for causes such as venous sinus

thrombosis (imaging studies), hormonal disorder (oral contracep-

tive use, Cushing’s or Addison’s disease, steroid withdrawal, hypo-

parathyroidism), iatrogenic cause (hypervitaminosis A, tetracycline

therapy in infants), chronic meningitis

management

■Lower ICP acutely if herniation threatened from structural lesion;

give mannitol

specific therapy

■Depends on cause

■Reduce ICP by hyperventilation & w/ mannitol when caused by acute

intracranial lesions; consider surgical decompression of cerebellar

hematomas or superficial cerebral hematoma exerting mass effect

■For pseudotumor, give acetazolamide, diuretics or both; prednisone

daily; repeated spinal taps, shunt placement or optic nerve sheath

fenestration may be needed to lower ICP or protect optic nerve; treat

any identified cause of pseudotumor

follow-up

■Depends on cause

■For pseudotumor, measure CSF pressure weekly, then monthly, until

control ensured; monitor visual fields & size of blind spot monthly

thereafter

complications and prognosis

■Depends on cause of increased ICP

■Optic atrophy w/ resultant blindness is the consequence of untreated

pseudotumor; idiopathic pseudotumor is self-limited & treatment

can typically be reduced and discontinued after several months

Intracranial Hypotension..............................

MICHAEL J. AMINOFF, MD, DSc

history & physical

■Headache, relieved by recumbency & worsened by upright position;

worsened by Valsalva maneuver