Introduction Spontaneous intracranial hypotension (SIH) is classically characterised by orthostatic headache resulting from loss of cerebrospinal fluid (CSF) volume, where lumbar puncture or spinal/cranial surgery is not the cause of CSF leakage. The estimated incidence of SIH is 5/100,000/year, half that of sub–arachnoid haemorrhage, yet the disorder remains under–recognised. Almost all patients are misdiagnosed at first, sometimes for many years, and severely disabling symptoms are common.

The International Classification of Headache Disorders (2004) diagnostic criteria for SIH include investigation results and treatment response, and their fallibility has been highlighted in a call for revised criteria. However, neither have a strong focus on the nature and chronology of symptoms that might assist the clinician to first suspect this disabling condition.

Methods In order to better understand the ‘story’ of a patient with SIH we retrospectively reviewed case notes of 8 cases seen at our institution between 2010–2012.

Results 5/8 patients were female, median age 33.5 years (range 20–53). 7/8 patients were initially misdiagnosed, with a median delay to diagnosis of 4 months (range 0.13–24). 5/8 patients had a thunderclap onset, 2/8 sub–acute (hours), and 1/8 gradual (days). 7/8 patients suffered a pattern of new onset daily headache from onset, with one having initially episodic (cough–induced) headaches developing in to chronic daily headache. A clear precipitating activity such as squatting, coughing and weightlifting, was only apparent in 3/8 patients.

All patients described initial onset of pain in the cranio–cervical region. In 3/8 this radiated to the orbito–frontal region and in (an independent) 3/8 the top of the head. Despite the diagnostic hallmark of SIH being regarded as orthostatic headache, 3/8 patients reported no positional worsening of their symptoms. Two of these 3 patients had had symptoms for one year, but the third only for 4 days. Bizarre sounding additional symptoms were common, leading to diagnoses of anxiety or a psychogenic nature in some. These included cranial and limb sensory symptoms, sensations like trickling water (head and back), tinnitus, “gnawing” and “crushing” facial pain, neck stiffness and visual symptoms. Two patients collapsed at onset, one with syncope.

4/8 patients had entirely normal neuroimaging (8/8 CT, 6/8 CT and contrast–enhanced MR brain +/–MR cervical spine). Response to treatment (blind epidural blood patch) was rapid and dramatic in 6/8, but required a 2nd procedure in 3 patients. Relapse occurred in one patient.

Conclusions SIH is an under–recognised but fairly common disorder. Clinical examination is usually normal, and confirmation of the diagnosis requires investigations and treatment not used routinely in the management of headache. Investigations, including contrast–enhanced neuroimaging, are often normal in the acute or chronic phase. Clinical history taking skills are therefore paramount in recognising this disorder. Characteristic features include a new daily persistent headache in a cranio–cervical distribution, with often bizarre sounding additional symptoms. Our results challenge the prevailing notions that thunderclap onset is rare and orthostatic headache is a mandatory criterion for this diagnosis.