Do not take sudden, unusual headaches lightly, especially those so intense they feel as though a blunt object has struck the head. Medical experts liken the pain to being struck by lightning.
The headache may subside just as suddenly, leading those who experience it to dismiss it as a migraine or attribute it to physical exhaustion or emotional stress.
After taking medication and resting for a while, they resume their daily routines, giving little further thought to the episode.
Medical experts, however, warn that this pattern of headache could signal a life-threatening medical emergency, even when no other symptoms, such as limb weakness, develop following the attack.
BRAIN HAEMORRHAGE, NARROWING OF BLOOD VESSELS
This condition, according to Universiti Malaya Medical Centre (UMMC) consultant neurologist Dr Schee Jie Ping, is known as a ‘thunderclap’ headache, characterised by an extremely severe pain that reaches maximum intensity within less than a minute, sometimes in just a few seconds.
“This term is not a diagnosis of a specific disease, but rather a clinical warning sign that requires doctors to investigate the underlying cause. The fact that the pain subsides does not mean the danger has passed,” he told Bernama.
He said the pain is distinct from a migraine because of its sudden onset and rapid escalation to maximum intensity.
“Migraines usually develop gradually, unlike thunderclap headaches which peak within seconds. Therefore, migraine sufferers should seek immediate medical assessment if they experience a sudden attack that is distinctly different from their usual headaches,” he said.
Dr Schee said several conditions could cause thunderclap headaches, with one of the most frequently diagnosed being subarachnoid haemorrhage (SAH), a type of bleeding in the narrow space between the brain and the thin tissues that cover and protect it. The most common cause of SAH occurring in the absence of a head injury is a ruptured brain aneurysm.
“An aneurysm is a bulge that forms on the wall of a weak artery. If an aneurysm ruptures, the resulting bleeding can cause the patient’s condition to deteriorate rapidly, leading to permanent disability or death. This situation requires emergency treatment,” he explained.
He also said that most unruptured aneurysms do not cause symptoms. Some may produce symptoms if they press against nearby nerves or structures. When an aneurysm ruptures and causes a subarachnoid hemorrhage, a thunderclap headache may be the first symptom.
“An exceptionally severe headache that reaches its peak within seconds requires immediate evaluation in an emergency department, even if the pain subsequently subsides,” he said.
He added that aneurysms could develop due to several risk factors, including smoking and high blood pressure. The risk is also higher among individuals with a family history of brain aneurysm or certain genetic conditions.
Dr Schee said thunderclap headaches could also be a symptom of reversible cerebral vasoconstriction syndrome (RCVS), a condition involving temporary narrowing of the arteries in the brain, which generally resolves within three months.
Patients with RCVS may experience recurrent sudden-onset headaches, usually within the first one to two weeks. Although headache may be the only initial symptom, the condition can lead to brain haemorrhage, ischaemic stroke and seizures.
“RCVS can also affect otherwise healthy individuals, including women in the postpartum period and those exposed to certain medications, such as nasal decongestants and serotonin-related drugs, as well as recreational drugs,” he said, advising patients to inform their doctors about any medication and supplement they are taking to facilitate clinical assessment.
TIMELY ASSESSMENT CRUCIAL TO DIAGNOSIS
On clinical management, Dr Schee said timing is critical in determining the underlying cause of a thunderclap headache. A non-contrast computed tomography (CT) scan of the brain, which does not involve the injection of contrast dye, is usually performed as the initial screening procedure.
The scan is most effective in detecting brain haemorrhage when performed within the first six hours after symptoms begin.
“For patients who seek medical attention within the first six hours and have a completely normal neurological examination, a high-quality non-contrast CT scan is generally sufficient to rule out brain haemorrhage, provided the radiologist confirms that there are no signs of bleeding,” he said.
However, if the scan is performed after the six-hour window or doctors still have clinical concerns, further investigations, such as a lumbar puncture (LP), may be considered.
The procedure involves collecting a sample of cerebrospinal fluid (CSF) using a needle inserted into the lower back after local anaesthesia is administered. The sample is then analysed in a laboratory to detect signs of bleeding or infection in the nervous system.
FURTHER SCREENING, FOLLOW-UP
Apart from a CT scan and LP, advanced imaging techniques, including CT angiography using contrast dye, magnetic resonance angiography and magnetic resonance imaging, can also be used depending on the suspected underlying cause.
However, if all these investigations return normal results, with no evidence of bleeding, structural damage or narrowing of blood vessels in the brain, doctors would generally manage the episode as a primary thunderclap headache.
“These (initial) investigations are necessary to guide treatment. Once suspected conditions such as brain haemorrhage and RCVS have been ruled out, doctors will focus on symptomatic treatment by prescribing appropriate pain medication to control the headache.
“This type of headache generally subsides on its own over several days or weeks without causing any long-term effects,” Dr Schee added.
However, he explained that patients whose thunderclap headaches are caused by brain haemorrhage following a ruptured aneurysm would require hospital admission and further treatment.
“Patients diagnosed with RCVS, meanwhile, will be treated by identifying and removing the triggering factors, such as decongestant medication, managing the pain and monitoring for complications,” he said.
He added that recent studies have shown that steroid-based anti-inflammatory medications were unsuitable for patients with RCVS as they could potentially worsen the narrowing of blood vessels.
“This information is important to prevent confusion among frontline healthcare practitioners when managing patients who present with sudden-onset headaches,” he said.
ONLY OUTWARDLY STABLE
Meanwhile, UMMC Emergency Medicine Department clinical specialist Dr Salha Mohd Fadil said one of the main challenges in treating patients with thunderclap headaches is that they could appear stable despite having a serious underlying condition.
“For example, a patient with SAH may still be able to walk and talk, while another patient with the same condition may experience a deterioration in consciousness.
“Therefore, a patient’s outward appearance alone should never be used to determine whether they are out of danger,” she said, adding that patients are assessed based on their overall clinical condition, including vital signs such as blood pressure, heart rate and oxygen levels, as well as their level of consciousness.
Citing an international study published in the ‘Emergency Medicine Journal’ in 2022, Dr Salha said although the study found that most thunderclap headaches were not associated with serious conditions, this did not mean that those experiencing them should take the symptoms lightly.
“The study involved 4,536 patients who presented at emergency departments in 67 hospitals in 10 countries, of whom 644 experienced thunderclap headaches.
“Of the 644 patients, 10.9 percent were found to have serious underlying causes, including conditions that could be life-threatening and impair brain function, and required immediate emergency treatment. These included stroke and meningitis. Within the same group, 3.6 percent had SAH,” she said.
She said the findings reinforced the importance of seeking further medical assessment at a hospital following a thunderclap headache.
PROMPT ACTION CAN SAVE LIVES
Dr Schee, meanwhile, said thunderclap headaches could occur during physical activities such as exercising, lifting heavy objects, coughing, straining or sexual intercourse.
“Anyone experiencing such an attack should stop whatever they are doing immediately and seek medical assistance. They should not drive themselves to hospital, but instead ask someone for help or call 999,” he said.
Dr Salha advised members of the public assisting someone experiencing a thunderclap headache not to leave the person alone, and to monitor their breathing and gather important information, including the time the headache began as well as the patient’s medication list.
“If the patient is unconscious but breathing normally, place them in the recovery position, lying on their side. If they are not breathing normally, begin CPR (cardiopulmonary resuscitation) and use an AED (automated external defibrillator), if available. Also call for emergency assistance immediately,” she added.
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