Pseudotumor cerebri associated with lithium therapy in two patients.

The authors report two cases of pseudotumor cerebri in patients taking lithium for treatment of bipolar disorder. Pseudotumor cerebri is a poorly understood syndrome characterized by chronic headaches, bilateral papilledema, and increased intracranial pressure without localized neurologic signs or symptoms, intracranial mass, or hydrocephalus. Ventriculography, computed tomography, and nuclear magnetic resonance imaging reveal normal or small ventricles. Multiple etiologies may include Vitamin A toxicity, obesity, head trauma, hypothyroidism or hyperthyroidism, prolonged steroid therapy or its withdrawal, Addison's disease, Cushing's disease, pituitary insufficiency, and lithium therapy. Patients treated with lithium whose antidiuretic hormone-cyclic adenosine monophosphate mechanism is disturbed are most likely to develop pseudotumor cerebri via disregulation of sodium balance, thyroid-stimulating hormone production, and glucose metabolism. The authors recommend careful medical monitoring to avoid iatrogenic effects of lithium, including pseudotumor cerebri.