BACKGROUND: Laughing is a rare precipitating factor for headaches, and the pathogenesis underlying laugh-induced headache (LH) remains unclear. METHODS: Two cases of headache triggered predominantly by laughing were presented in this article. We also reviewed the published English literature regarding LH, summarized the clinical characteristics of LH, and discussed the probable pathophysiological mechanisms. RESULTS: In the first patient, magnetic resonance imaging of the brain revealed cerebellar tonsillar herniation through the foramen magnum. In the second patient, we did not find any evidence of intracranial disease. The literature review showed that LH is a mild to severe, non-pulsating headache. In most cases, the duration of each attack was limited to a few minutes. The headache usually bursts after laughing and reaches its peak almost immediately. In some cases, the headache can only be induced by mirthful laughing rather than by fake laughing. CONCLUSION: LH can be categorized as primary LH and secondary LH. Changes in the spatial structure in the posterior cranial fossa and cerebrospinal fluid circulation may contribute to the development of secondary LH. Primary LH, primary cough headache, and primary exercise headache may share some common pathogenesis. And we speculate that the regions of the brain associated with the expression of mirth might be associated with LH.
BACKGROUND: Laughing is a rare precipitating factor for headaches, and the pathogenesis underlying laugh-induced headache (LH) remains unclear. METHODS: Two cases of headache triggered predominantly by laughing were presented in this article. We also reviewed the published English literature regarding LH, summarized the clinical characteristics of LH, and discussed the probable pathophysiological mechanisms. RESULTS: In the first patient, magnetic resonance imaging of the brain revealed cerebellar tonsillar herniation through the foramen magnum. In the second patient, we did not find any evidence of intracranial disease. The literature review showed that LH is a mild to severe, non-pulsating headache. In most cases, the duration of each attack was limited to a few minutes. The headache usually bursts after laughing and reaches its peak almost immediately. In some cases, the headache can only be induced by mirthful laughing rather than by fake laughing. CONCLUSION:LH can be categorized as primary LH and secondary LH. Changes in the spatial structure in the posterior cranial fossa and cerebrospinal fluid circulation may contribute to the development of secondary LH. Primary LH, primary cough headache, and primary exercise headache may share some common pathogenesis. And we speculate that the regions of the brain associated with the expression of mirth might be associated with LH.