Pathological laughing and crying

Pathological laughing and crying (PLC) is an emotional expression disorder in which patients experience relatively uncontrollable episodes of laughing or crying, or both. The laughter or crying are unconnected to triggering stimuli which would have led to laughing or crying before the onset of the condition. PLC is therefore quite different from mood disorders, where laughing and crying are expressed in tandem with feelings of happiness or sadness. PLC is a frequent consequence of brain injury, seen in approximately 10-20% of stroke, 40% of Alzheimer’s, 7-10% of multiple sclerosis, 20-50% of amyotrophic lateral sclerosis, 5-10% of traumatic brain injury patients, 6% of Parkinson's patients as well as about 5% of noncerebellar type multiple system atrophy (MSA), and 37% of patients with the cerebellar type of MSA [Tateno A, Jorge RE, & Robinson RG. 2004. Pathological laughing and crying following traumatic brain injury. "Journal of Neuropsychiatry and Clinical Neuroscience" 16:426-434.] [Parvizi J, Arciniegas DB, Bernardini GL, Hoffmann MW, Mohr JP, Rapoport MJ, Schmahmann JD, Silver JM, Tuhrim S. 2006 Diagnosis and Management of Pathological Laughter and Crying. "Mayo Clinic Proceedings" 811482-1486] .

Studies have reported an inconsistent pattern of association between PLC and major depression, sometimes an association is found, other studies find none.

PLC has long been thought to result from loss of voluntary inhibition of a postulated centre for laughing and crying in the upper brainstem [Wilson SAK. 1924. Some problems in neurology II: Pathological laughing and crying. "Journal of Neurology and Psychopathology" 6:299-333.] . More recent authors have suggested that prefrontal cortex is involved [McCullagh S, Moore M, Gawel M, Feinstein A. 1999. Pathological laughing and crying in amyotrophic lateral sclerosis: an association with prefrontal cognitive dysfunction. "Journal of Neurological Sciences" 169:43–48] or that lesions in the cerebro-ponto-cerebellar pathways influence cerebellar structures that adjust the expression of laughter and crying [Parvizi J, Anderson SW, Martin CO, Damasio H, & Damasio AR> 2001. Pathological laughter and crying: A link to the cerebellum. "Brain" 124:1708-1719.]

Patients administered tricyclic antidepressants show significant improvements PLC, with no effect on coexisting depression [Schiffer RB, Herndon RM, Rudick RA.1985. Treatment of pathologic laughing and weeping with amitriptyline. New England Journal of Medicine 312:1480-1482.] [Robinson RG, Parikh RM, Lipsey JR, Starkstein SE, Price TR. 1993. Pathological laughing and crying following stroke: validation of a measurement scale and a double-blind treatment study. American Journal of Psychiatry. 150:286-293.] Reports that patients show partial to full remission within a week of starting low doses of SSRI suggest that serotonergic systems are involved. [van Wattum PJ & Chiles C. 2001. Rapid response to low dose citalopram in pathological crying "General Hospital Psychiatry" 23:167-­168.] By comparison, major depression does not respond to SSRIs before three to five weeks of treatment. AVP-923, a compound consisting dextromethorphan and quinidine, has also shown significant theraputic effect [Brooks BR, Thisted RA, Appel SH, et al, AVP-923 ALS Study Group. 2004. Treatment of pseudobulbar affect in ALS with dextromethorphan/quinidine: a randomized trial. "Neurology" 63:1364-1370] [Panitch HS, Thisted RA, Smith RA, et al, 2006. Pseudobulbar affect in Multiple Sclerosis Study Group. Randomized, controlled trial of dextromethorphan/quinidine for pseudobulbar affect in multiple sclerosis. "Annals of Neurology" 59:780-787.] .

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