Orthostatic headache without CSF leak

To describe the syndrome of orthostatic headache without CSF leak and propose potential mechanisms.From among 125 patients referred to one of us (B.M.) over a 5-year period for evaluation of orthostatic headache and suspected CSF leak, those patients with negative head and spine MRI, normal radioisotope cisternography and CT myelography, and normal recumbent CSF opening pressure were identified and their medical records reviewed.Six patients satisfied the above criteria for absence of CSF leak. Four patients were men. Mean age at the time of evaluation was 39 years (range 20 to 65). Median duration of symptoms prior to evaluation at our institution was 2 years (range 0.5 to 16). An inciting event was present in two patients. Cochleovestibular symptoms were present in five patients. Mean CSF opening pressure was 140.3 mm H2O (range 86 to 186). Two patients underwent autonomic reflex screens; neither showed postural tachycardia syndrome. After mean follow-up of 45.5 months (range 31 to 67), one patient had experienced a complete spontaneous recovery while five had persistent orthostatic headache.Orthostatic headaches can occur without evidence of intracranial hypotension or detectable CSF leak despite extensive diagnostic testing. Clinical features alone are unlikely to differentiate between orthostatic headache with and without identifiable CSF leak. Potential mechanisms include 1) very slow or intermittent CSF leak that cannot be detected at the time of evaluation or by current diagnostic means or 2) increased compliance of the lower spinal CSF space without actual leak.