The old adage ‘Laughter is the best medicine’ may not hold true for at least nine cases included in a 2017 review article by Ye et al. published in the Journal Headache by the American Headache Society. The nine individuals shared a common symptom and that is headache induced by laughter. Ironic as it may sound, too much laugh can make you hurt.
Laughter induced headache or LH is a rare phenomenon. The prevalence is still undetermined. Although it shares features with cough and exercise induced headache, it is not yet listed in the International Classification of Headache Disorders.
In general, LH is sudden in onset usually lasting less than a minute but may extend up to fifteen minutes. It reaches its peak immediately after a mirthful or joyous laugh. It is mild to severe in intensity but most cases are severe. It is nonpulsating and occurs only with a hearty, spontaneous laugh. The headache seems to be discerning as it does not happen with a fake laugh.
There are two types of LH. Primary LH has no organic basis which means that there is no structural abnormality on imaging. Secondary LH, on the other hand, is caused by a variety of conditions. Chiari malformation 1 or cerebellar tonsillar herniation is one of the most common causes of secondary LH and is present in the five cases described in the article. The other conditions include intracranial tumors, arachnoid cysts, unruptured aneurysms, deep dural sinuses caused by giant Pacchionian granulations, and thrombophlebitis.
Primary LH is associated with sustained, strenuous physical activity or exercise while secondary LH occurs like cough induced headache. The exact pathogenesis of laughter induced headache remains unclear. Some mechanisms can help explain the headache. Primary LH can increase brain volume by virtue of retrograde jugular venous flow which induces intracranial venous congestion. Distension of the cerebral veins and increase in the activity of the trigeminal nerve cause pain.
Laughter in itself can be a form of a Valsalva maneuver or exhalation against a closed airway. This can help explain secondary LH. For those with cerebellar tonsillar herniation, the Valsalva maneuver can result to transient pressure changes between intracranial and intraspinal compartments. The herniation can put pressure on pain sensitive structures such as nerves, meninges, and blood vessels.
Emotions also contribute in the production of headache. When one’s emotion is altered it can lead to changes in neural function. One theory postulates that the affective process is involved rather than the cognitive since merely understanding a joke does not lead to headache. The mesolimbic dopaminergic reward system is involved in the affective processing. Some important areas of the brain such as the amygdala and the hypothalamus play roles in the production of an emotional laugh.
Majority of the cases of LH respond to analgesics and nonsteroidal anti-inflammatory drugs such as indomethacin. Others respond to antidepressants and drugs used for headache or migraine prophylaxis. Although a rare occurrence, laughter induced headache must be investigated to rule out causes of secondary LH and to address them appropriately.
The great comic actor Charlie Chaplin once said to truly laugh, you must be able to take your pain and play with it. This might go handy for those with laughter induced headache as the pain is as much a physical kind as it is emotional.
Ye, R. et al. Laugh-Induced Headache: Clinical Features and Literature Review. Headache. American Society of Headache.2017.
Boga, T. et al. Laugh headaches: A rare form of headache associated with type 1 Arnold-Chiari malformation. Internal Medicine Journal. 2011.
Morales-Asin, F. et al. Long-term evolution of a laughing headache associated with Chiari type 1 malformation. Headache.1998.
Giraud, P. et al. Laughing headache with giant pacchionian granulations. Headache.2013
Mobbs, D. et al. Humor modulates the mesolimbic reward centers. Neuron.2003.