Abstract
Introduction
Thunderclap headache (THC) is an extremely intense headache of rapid development which may be the presenting sign of an intracranial aneurysm near rupture (‘sentinel headache’), dural sinus venous thrombosis or pituitary apoplexy (1–3). A benign form exists triggered by physical exertion or occurring spontaneously. Benign THC may be caused by occipital neuralgia (4). Dodick et al. reported two patients with benign THC accompanied by diffuse, multifocal reversible cerebral vasospasm (5). Idiopathic stabbing headache or ice pick-like pain refers to intense, sudden, brief, piercing pain, felt on any part of the head, commonly reported by migraineurs (6, 7). Adolescents may experience ice pick-like pain in the absence of other features of migraine (juvenile stabbing headache) (8). A patient with chronic recurrent exploding head syndrome (EHS) with unusual characteristics is described. She had chronic tension-type headache.
Case report
A 71-year-old female was referred to the neurologist because of global pressure daily headache of many years duration. She described long-standing episodes of startle, generalized twitching of the muscles and severe, brief stabbing pains on the parietal regions of the head, before falling asleep at night. These episodes were simultaneously associated with the hearing of a loud clap perceived over both ears, or the sound of near thunder that caused a great deal of apprehension. She did not see lights. These episodes took place 3 nights a week on average. There were no precipitants. She had history of chronic generalized anxiety. Her father and two brothers had chronic tension-type headaches. She was a chronic cigarette smoker. Her blood pressure was 140/80, her heart rate was 70 and her temperature was normal. She was well nourished.
General physical examination was normal. Her neurological examination on several occasions, including mental status, cranial nerves, muscle strength, muscle tone, osteotendinous reflexes, cerebellar function, gait and sensory testing, was also normal. There were no pathological reflexes. Electroencephalogram (EEG), brain magnetic imaging (MRI) and brain magnetic angiography (MRA) were normal. Overnight sleep studies completed after treatment was initiated revealed no sleep apnoea, nocturnal seizures, involuntary movements or somnambulism.
She was prescribed valproic acid, amitriptyline, propranolol, oxycodone and gabapentin for her headache with no improvement. Indomethacin was not prescribed. Slow-release nifedipine, 90 mg a day, completely suppressed her nocturnal episodes of stabbing head pains and loud sounds. In 3 years of follow-up visits no new symptoms have appeared. Her daily headache was stopped with PRN butalbital and aspirin.
Discussion
Although this patient had very severe acute head pain, she could not be diagnosed with THC because of the following reasons: (i) her head pain was of brief duration; (ii) it was associated with the hearing of alarming loud sounds of either someone clapping on her ears or the sound of nearby thunder; (iii) it occurred always at the same time before falling asleep; (iv) she experienced simultaneously generalized startle with sudden jerking of her body, that represented hypnagogic myoclonus, a normal phenomenon before falling asleep (9); (v) there was no evidence of intracranial lesions, including a ruptured aneurysm. Because she had no epilepsy or primary sleep disorders she could not be diagnosed with ictal head pain or nocturnal paroxysmal dystonia.
This patient had exploding head syndrome (EHS), a curious benign clinical syndrome that is probably under-recognized by neurologists. It is characterized by terrifying sensations of loud sounds or flashing lights before falling asleep and is normally not associated with sudden pain or headache (10). Rarely, EHS may be confused with nocturnal epilepsy but the EEG and polysomnography recordings are normal (11, 12). I believe this patient had a variant of EHS with superimposed ISH, another benign symptom more often experienced by patients with migraine, yet causing significant apprehension in the patient and occasionally resulting in the performance of unnecessary tests (7).
Of interest was this patient's response to the administration of nifedipine that suppressed her nocturnal episode of EHS but failed to improve her chronic tension headache. The dissociation in the therapeutic response of EHS and chronic daily headache on this patient suggests that they have different pathogenetic mechanisms. It is legitimate to speculate that EHS is perhaps a paroxysmal symptom arising from transient calcium channel dysfunction. This dysfunction will be similar to the one observed in patients with episodic ataxia and familial hemiplegic migraine that results from a mutation in the CACNA1A gene located in chromosome 19. The CACNA1A gene encodes for the α 1-A subunit of the neuronal P/Q type voltage-gated calcium channel (13).