Thunderclap headache triggered by micturition: responsive to nimodipine

TCH is a severe, hyper-acute headache of the sudden-bursting type like a ‘clap of thunder’, of which the pain intensity reaches a peak at onset usually within 60 s. TCH is considered to have two types: primary TCH and secondary TCH. Secondary TCH could be attributed to vascular causes including subarachnoid hemorrhage (SAH), cerebral venous sinus thrombosis (CVST), pituitary apoplexy, ischemic stroke, severe hypertension crisis, and nonvascular causes including spontaneous intracranial hypotension, third ventricle colloid cyst, intracranial infections [3]. Our MRI, MRA, and CSF examinations had excluded these possible underlying causes in this patient. In very rare situations, micturition can also trigger sudden-bursting severe headache in patients, but all these reported cases were accompanied with pheochromocytoma in bladder [6, 9, 10] and the headaches were usually associated with elevations of blood pressure following micturition [5]. The contrast-enhanced abdomen CT scan and the unelevated blood pressure during headache attack had also excluded the underlying causes of bladder pheochromocytoma. The headache in our patient seems in consistent with the presentations of primary TCH. Apart from the triggering factor micturition, the headache of our patient met the diagnostic criteria for primary TCH: (i) Severe head pain, (ii) sudden onset, reaching maximum intensity in <1 min, lasting from 1 h to 10 days, (iii) Does not recur regularly over subsequent weeks or months, and (iv) Not attributed to another disorder. Though evidence that thunderclap headache exists as a primary condition is poor, primary TCH has been described as a distinct entity [4]. A primary TCH may occur spontaneously while the patient is at rest or during light activities or may only be triggered by exertion, sexual activity, coughing and thus be classified as primary cough headache, primary exertional headache and primary headache associated with sexual activity respectively. The TCH in our patient was exclusively triggered by micturition and there was no serious underlying pathology identified to explain this TCH, thus it might be plausible to consider the micturitional headache as ‘primary’. This micturitional headache is an unusual headache not defined by the ICHD-II, therefore the reporting of this case might be helpful for the more detailed headache classification in the future.

Our patient’s response to nimodipine was dramatic and impressive during the time when headaches were still worsening. The close chronological concordance between headache relief and initiation of oral nimodipine was in favor of the direct therapeutic effect of nimodipine. Indeed, nimodipine is currently recommended in aneurysmal subarachnoid hemorrhage in order to prevent vasospasm based on its role in the relaxation of the smooth muscle of arterial blood vessel walls [11]. Thus, the recurrent micturitional TCH in our patient might be associated with cerebral vasospasm though the vasospasm was not visible by MRA. Efficacy of nimodipine was reported in primary TCH [12] as well as in primary bathing TCH [13] with vasospasm detected or non-detected. It has been suggested that primary recurrent TCH can be divided in two groups: one with diffuse vasospasm and the others without any visible vasospasm by MRA, and primary TCH, to some extent, share the same spectrum with reversible cerebral vasoconstriction syndrome (RCVS) based on their similar clinical features and the same rate of ischemic complications [14, 15]. The therapeutic efficacy of nimodipine in vasospasm associated primary TCH and RCVS as well as in our micturitional headache may suggest a similar pathogenic mechanism of vasospasm for both conditions. Unfortunately, a late control MRA or transcranial Doppler was not conducted to show any presence of late vasospasm eventually in this patient. Recently, it has been shown that, in some patients, the maximal vasospasm detected by transcranial Doppler or by MRA is respectively at 18–25 days and at 16 ± 10 days after TCH onset [16, 17]. The pathophysiological relationship between micturition and cerebral vascular change is poorly understood and speculative. There is anecdotal evidence suggesting that abdominal support, voluntary diaphragm and abdominal muscle co-activation, is necessary for effective voiding, this results in an alteration of intra-abdominal pressure. This was suggested to have causative relationship to TCH triggered by singing [18]. This intra-abdominal pressure alteration may trigger an unclear neural reflex resulting in a cerebral vascular change.

Involvement of non-organic, psychiatric factors should also be considered to contribute to the recurrent headaches, as a mild depressive (HAM-D = 16) and a mild anxiety disorder (HAM-A = 9) were revealed and a distinct phobia for micturition also found in our patient. Whereas, the negative result of the antipsychotic treatment seemly indicated that the psychiatric factors may not play a critical role in the headache recurrence. Further case reports may help to elucidate the possible role of psychiatric factors in the micturitional headache.

In summary, we treated a patient with recurrent TCH apparently triggered by micturition without any underlying organic causes, which was responsive to nimodipine dramatically. We hypothesize that the pathophysiology of this primary micturitional headache is associated with cerebral vasospasm induced by neural reflex after the intra-abdominal pressure is altered.