Low-dose levodopa is effective for laryngeal dystonia in xeroderma pigmentosum group A

Abstract

Xeroderma pigmentosum (XP), a genetic disorder in DNA nucleotide excision repair, is characterized by skin hypersensitivity to sunlight and progressive neurological impairment. Laryngeal dystonia and vocal cord paralysis are complications that can arise in older XP group A (XPA) patients. We report three patients with XPA being administered low-dose levodopa (0.3–1.5 mg/kg/day) for laryngeal dystonia. Patients were aged from 13 to 18 years, exhibited paroxysmal choking and inspiratory stridor, and were diagnosed with laryngeal dystonia. Two XPA patients responded to low-dose levodopa, and paroxysmal choking and involuntary movements resolved, although one of the two patients showed incomplete resolution due to suspected vocal cord paralysis. The other patient was unable to tolerate the medication because of a transient decrease of muscle tone in the extremities. We previously reported a decreased immunostaining of dopaminergic (DA) terminals in the basal ganglia of XPA patients, which may be involved in laryngeal dystonia. Low-dose levodopa has been reported to alleviate DA receptor supersensitivity in tic patients, while laryngeal dystonia occurs in patients with tardive dyskinesia caused by DA receptor supersensitivity. Thus, low-dose levodopa may improve laryngeal dystonia by alleviating DA receptor supersensitivity in XPA patients. We recommend that low-dose levodopa be used for treatment of paroxysmal respiratory disturbances and/or involuntary movements in XPA patients.