Headache in spontaneous intracranial hypotension: an overview with indications for differential diagnosis in the clinical practice.

Headache is the most common symptom of spontaneous intracranial hypotension (SIH). The present review focuses on data regarding headache features reported in the most relevant published articles and summarizes the main SIH headache features, namely, orthostatic headache, headache triggered by Valsalva maneuver, pattern of onset of headache, and location and quality of headache. Published data indicate that the clinical suspect of this disorder may be challenging, due to its protean presentation. Among the main implications for clinical practice, we suggest to suspect SIH in all patients with a new onset headache, as different forms of primary and secondary headache should be considered in the differential diagnosis of SIH, particularly cervicogenic headache, new daily persistent headache, and headaches precipitated by Valsalva maneuver. The clinical interview must include specific questions on the possible orthostatic feature of headache, although its absence should not make clinicians to reject the SIH hypothesis as headache cannot be orthostatic in each patient and in all periods of the natural history of the disease. Other disorders with orthostatic symptoms, such as in postural tachycardia syndrome (POTS) and persistent postural-perceptual dizziness (PPPD), should be considered in the differential diagnosis. Awareness that SIH can present with acute, sudden onset requires that clinicians working in the emergency settings should consider SIH in the range of diagnoses of thunderclap headache.