Nonpositional headache caused by spontaneous intracranial hypotension

A 68-year-old man awoke with a headache and a whirring noise in both ears. There was no history of trauma. The headache was bifrontal and associated with nausea and posterior neck pain. The headache was nonpositional, e.g., it did not worsen upon standing or improve when lying down. Because the headache persisted and would occasionally awake him from sleep, he sought advice 1 month after the onset of symptoms. He had a history of coronary artery disease. Neurologic examination was normal. Brain MRI showed bilateral chronic subdural hematomas, a sagging brain, and diffuse pachymeningeal enhancement (figure A through C). Coagulation studies were normal. The subdural hematomas were believed to be the cause of his headaches and were drained. MRI of the spine was normal. Indium-111 radionuclide cisternography showed a focal CSF leak at the left lumbosacral junction (figure, D); lumbar puncture at the time revealed an opening pressure of 0 cm H₂O. A lumbar epidural blood patch was placed and resulted in significant but temporary improvement of the headaches. The blood patch was repeated, with complete resolution of the headaches.

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Figure. (A) Axial T2-weighted MRI shows bilateral chronic subdural hematomas. (B) Sagittal T1-weighted MRI shows severe flattening of the pons and inferior displacement of the optic chiasm. (C) Axial T1-weighted gadolinium-enhanced MRI shows diffuse pachymeningeal enhancement. (D) Radionuclide cisternogram shows increased uptake of tracer at the left lumbosacral junction (arrow).

This patient had spontaneous intracranial hypotension, as evidenced by the characteristic findings on MRI examination of the brain and lumbar puncture.¹ However, unlike most reported patients with spontaneous intracranial hypotension, our patient's headache had no orthostatic features, even on detailed questioning. Patients with chronic intracranial hypotension often have headaches that have become nonpositional; however, a history of orthostatic headaches at the onset of symptoms generally can be elicited.¹ Patients with spontaneous intracranial hypotension and no history of orthostatic headaches are rarely reported.² The presence of the subdural hematomas in our patient may have prevented orthostatic headaches from developing by correcting the abnormally low intracranial pressure or volume.

Spontaneous intracranial hypotension caused by a spinal CSF leak is an increasingly recognized clinical entity. The exact cause of these CSF leaks usually remains unknown, but a combination of an underlying weakness of the spinal meninges, predisposing to the formation of meningeal diverticula or dural tears, and a trivial precipitating traumatic event generally is suspected.^1,3 Subdural hematomas in the setting of intracranial hypotension have long been recognized and, in 1953, Schaltenbrand⁴ stated that aliquorrhea (low spinal fluid pressure) is one, if not the most important, cause of chronic subdural hematoma. Subdural hematomas may be caused by the loss of buoyancy and downward displacement of the brain resulting in tearing of bridging veins. Persistent spinal CSF leakage may result in recurring subdural hemorrhages,² and we therefore elected to place an epidural blood patch. If the subdural hematomas recur in our patient, we would recommend definitive surgical treatment of the focal CSF leak.⁵

Spontaneous intracranial hypotension should be considered as a cause of subdural hematomas even in the absence of any history of positional headaches. Treatment of the underlying CSF leak may prevent the subdural hematomas from recurring.