Abstract
Thunderclap headache is well known to be a presenting feature of a variety of causal events. Indeed, a primary form is considered in the International Classification of Headache Disorders-II, but such diagnosis must be made only after exclusion of a possible secondary cause. We report a case of late-onset idiopathic aqueductal stenosis presenting with thunderclap headache, in the absence of abnormal neurological findings or indirect signs of raised intracranial pressure. The patient recovered completely after endoscopic third ventriculostomy. This case indicates primary aqueduct stenosis as a possible, never previously reported, cause of thunderclap headache.
Introduction
Thunderclap headache (TCH) refers to a severe and explosive headache with peak intensity at onset—as sudden and as unexpected as a ‘clap’ of thunder (1). The term was first used by Day and Raskin to describe the pain associated with an unruptured cerebral aneurysm (2). However, other potentially serious neurological disease can also present with TCH, including subarachnoid haemorrhage (3), cerebral venous sinus thrombosis (4), pituitary apoplexy (5), spontaneous intracranial hypotension (6), hypertensive encephalopathy (7), carotid artery dissection (8), retroclival haematomas (9), ischaemic stroke (10) and third ventricle colloid cyst (11). In some patients with TCH, angiography may detect transient diffuse vasospasm, in the absence of aneurysm or haemorrhage (12, 13), whereas in others no underlying secondary causes are found. Primary TCH is, indeed, classified in chapter 4.6 of the International Classification of Headache Disorders-II (14); however, diagnosis must always be reached after careful exclusion of a possible secondary origin through appropriate investigations. We report here a case, presenting with this distinctive headache profile, secondary to a not previously described condition.
Case report
Shortly after awakening, a 25-year-old woman abruptly developed a severe headache with immediate peak intensity. At the time of her evaluation at the Emergency Department, 2 h later, her headache persisted and was described as extremely severe (‘the worst of my life’), occipital, throbbing, associated with photophobia and phonophobia, without neck stiffness, nausea or vomiting.
Her past clinical history documented that in the last 20 years she had suffered from recurrent headache with intense alternating unilateral throbbing pain, nausea and vomiting, photo-, phono- and osmophobia, incapacitating with bed resting. The attacks had occurred twice a month, usually lasting for 12–24 h, and could be triggered by menstruation and heavy smells. She had never undergone brain imaging. She denied any other significant medical history or recent illness. She did not smoke or use alcohol and had not been taking any drugs in the immediate period before admission, excluding common analgesics (ibuprofen, naproxen) for migraine attacks. The patient's mother had experienced similar unilateral headache attacks with nausea, photophobia and phonophobia.
Physical examination showed an alert but suffering female. Vital signs were: temperature 36.6°C, regular pulse rate of 88 beats/min, blood pressure 130/80 mmHg and respirations 17 per minute. Neurological examination was normal, and specifically there were no signs of raised intracranial pressure (such as papilloedema, visual obscurations, diplopia or tinnitus). Blood examinations including blood count, electrolytes, C-reactive protein and
(A) T1-weighted sagittal MR image shows an enlargement of the third ventricle with a stenosis of the aqueduct and a comparatively small fourth ventricle. (B) Sagittal cine phase-contrast MR imaging at the level of the aqueduct canal shows a complete obstruction with no CSF flow through the aqueduct. The arrow indicates the obstruction point.
During the patient's hospital stay, her headache continued despite repeated use of ketorolac, corticosteroids and neuroleptics. Eight days after initial evaluation she underwent endoscopic third ventriculostomy, with CSF shunt between the third ventricle and the basal cisterns. Twenty-four hours after neurosurgery, her intractable headache had resolved and she had no further complaints. During the following 12 months, she just had seven menstruation-related migraine attacks. A 6- and 12-month follow-up with MRI of the brain showed a marked decrease in the size of the ventricular system.
Discussion
Primary AS constitutes about 10% of adult hydrocephalus (15). Headache occurs in approximately 50% of adult AS patients (16). It has been suggested to be caused by raised intracranial pressure because of impaired flow within the ventricular system (17) and may be associated with other unspecific signs of elevated intracranial pressure, such as transient visual scotomas, diplopia, tinnitus and papilloedema (16). To our knowledge, this is the first report of a TCH as the presenting and unique clinical feature of a primary AS, since other neurological findings were absent. The underlying mechanism of acute hydrocephalus as a trigger for TCH remains unknown: one could hypothesize merely a very sudden narrowing of the aqueduct or, alternatively, an acute decompensation of a more chronic hydrocephalus. Nevertheless, we could not exclude the possibility of an idiopathic TCH in a migraine patient, even if this hypothesis seems not to be supported by the clinical course of the disease. In summary, TCH seems to label a syndrome, sometimes associated with vasospasm or a structural lesion, but more often of benign aetiology. This case suggests that TCH could be listed as a potential, clinically isolated presentation of adult primary AS. The report again confirms that, before being classified as a primary, benign form, TCH must be adequately investigated to exclude a secondary aetiology.