Ellana Stinson, MD
Resident Physician, Department of Emergency Medicine
Medical College of Georgia, Augusta.

Larry Mellick, MD, MS, FAAP, FACEP
Professor of Emergency Medicine and Pediatrics
Medical College of Georgia

Pearl: Thunderclap headache refers to a sudden onset of severe headache described as a “clap of thunder,”which, to emergency physicians means subarachnoid hemorrhage (SAH) from intracranial aneurysm rupture. However, it is critical to be aware that other central nervous system conditions can present as a thunderclap headache. Some of these conditions are potentially life-threatening and pose diagnostic challenges.

Case: An 83-year-old man was brought to the emergency department by EMS after being found lying on the living room floor. The patient was alert and oriented and complained of a headache that woke him from sleep. The headache pain was described as constant and lasting for approximately 3-4 hours. Any history of trauma or loss of consciousness was denied. Upon obtaining further history, the patient denied a history of frequent headaches or migraines. On physical exam, the patient was awake, alert, and oriented. He appeared moderately uncomfortable and had nystagmus on right gaze.

His pain improved with fentanyl, benadryl, compazine, and cervical injection. The head CT showed old infarcts, but no evidence of subarachnoid hemorrhage (SAH). Tube 3 of his CSF tap showed 50-60 RBCs. Computerized tomogram angiography (CTA) was normal. After initial work-up, the patient’s headache returned worse than before. Neurology was consulted, and MRI/MRV was performed to rule out venous sinus thrombosis. This study was positive. (See Figure 1.)

Discussion: Thunderclap headaches (TCH) are headaches that are sudden in onset and severe in nature, often described as the “worse headache of my life.” The term was first used by Day and Raskin in an article published in the Lancet in 1986.¹ TCHs are most commonly associated with the onset of subarachnoid hemorrhage (SAH) from intracranial aneurysm rupture.² Other less known conditions also must be considered with atypical headache complaints. Various etiologies of TCH can be categorized into vascular disorders versus nonvascular intracranial disorders. (See Table 1.)

Subarachnoid hemorrhages occur in up to 25% of patients presenting with acute onset headache.³ Physical findings may include nausea, vomiting, neck pain, photophobia, neurologic signs (e.g., meningismus, nerve palsies, extremity weakness), and diminished level of consciousness. Lack of symptoms often leads to misdiagnosis, resulting in increased neurologic complications and worsened prognosis. An SAH typically lasts a few days and does not typically resolve within a few hours. On physical exam, there are typically no focal findings. Initial diagnostic testing should include a non-contrast head CT. Imaging has a very high sensitivity within the first 12 hours of SAH (100%) and decreases significantly after a week.^4,5 A lumbar puncture (LP) should be performed if the non-contrast CT-head is non-diagnostic. CSF analysis has an increased sensitivity if collected within 12 hours of onset.

Cerebral venous thrombosis (CVT), unlike other conditions, most often affects young adults and children, and the symptoms and clinical course are highly variable.⁶ The associated headache typically increases gradually over a couple of days, but can also start with a TCH. Presenting headaches may be localized or diffuse, persistent or positional in nature. However, TCH may be the main symptom in 10% of patients. Papilledema, seizures, focal neurologic deficits, and changes in mental status are other common findings. CT scans and LPs are commonly negative. Infrequent imaging abnormalities include hyperdensities in occluded sinuses, venous infarcts, and cerebral edema. LP abnormalities are not typically found, but uncommonly will result in elevated white blood cells, high protein, and lymphocytic pleocytosis, or elevated opening pressure. With increasing clinical suspicion, MRI/MRV should be performed.

Spontaneous cervical artery dissection often occurs secondary to hypertensive crisis or trauma. The onset of headache is more commonly gradual, but it may present as an instantaneous, excruciating, “thunderclap” headache that mimics a subarachnoid hemorrhage. Dissection is found in all age groups, but peaks in the fifth decade of life.7 Dissection of cervical arteries may be due to the greater mobility of the carotid and vertebral arteries at the base of the skull, which increases the risk of injury during contact with bony structures. Chiropractic manipulation of the neck has been associated with carotid-artery dissection. Other risk factors include connective tissue disorders and possible infectious triggers. Intimal tear of the artery results in formation of a false lumen and ultimately artery stenosis or aneurysmal dilatation. Symptoms include unilateral facial, head, or neck pain along with a partial Horner’s syndrome. These symptoms are found in fewer than one-third of patients, but the presence of any two symptoms should strongly suggest the diagnosis.⁷ Angiography remains the gold standard for diagnosis, but is steadily being replaced by MRA due to the higher resolution. Ultrasound also serves as a useful initial diagnostic technique.

Primary thunderclap headache is a headache of high intensity with abrupt onset and mimics a ruptured cerebral aneurysm. It is typically a very painful headache not attributable to another disorder. The diagnosis of primary TCH is made when all other potential underlying causes have been eliminated by diagnostic testing.⁸ The headache reaches maximal intensity within one minute and can last from one hour to 10 days.⁹ The prevalence is not known, but women between 20 and 50 years of age tend to present with this headache more commonly. The headache can be diffuse but is often occipital. Nausea and vomiting can be associated signs and symptoms. Neuroimaging and CSF examinations are normal.

By understanding the various presentations and etiologies of thunderclap headaches, the emergency medicine physician can more effectively evaluate patients who present with headaches that begin suddenly and are severe in nature.

References:

1. Day JW, Raskin NH. Thunderclap headache: Symptom of unruptured cerebral aneurysm. Lancet 1986;2:1247-8.
2. van Gijn J, Rinkel GJ. Subarachnoid haemorrhage: Diagnosis, causes and management. Brain 2001;124:249–78.
3. Linn FH, Wijdicks EF, van der Graaf Y, et al. Prospective study of sentinel headache in aneurysmal subarachnoid haemorrhage. Lancet 1994; 344: 590–93.
4. Edlow JA, Caplan LR. Avoiding pitfalls in the diagnosis of subarachnoid hemorrhage. N Engl J Med 2000;342:29–36.
5. Matharu MS, Schwedt TJ, Dodick DW. Thunderclap headache: An approach to a neurologic Emergency. Curr Neuro Neurosci Rep 2007;7:101-109.
6. Stam J. Thrombosis of the cerebral veins and sinuses. N Engl J Med 2005;352:1791-8.
7. Schievinik WI. Spontaneous dissection of the carotid and vertebral arteries. N Engl J Med 2001,344:898-906.
8. Schwedt TJ, Matharu MS, Dodick DW. Thunderclap headache. Lancet Neurol 2006;5:621-31.
9. http://ihs-classification.org/en/02_klassifikation/02_teil1/04.06.00_other.html

Online Sources:

1. http://www.uptodate.com/home/content/topic.do?topicKey=headache/3013
2. http://emedicine.medscape.com/article/761451-overview
3. http://emedicine.medscape.com/article/1164341-overview

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