Nocturnal sleep-related scratching disorder as a possible variant of NREM arousal disorder: Clinical features and polysomnographic study of four newly reported cases.

A clinical variant of NREM arousal disorder is described manifesting with predominantly injurious, and exclusively sleep-related scratching without any conscious awareness, and without a history of dermatologic disease. Four patients were clinically evaluated and underwent videopolysomnography (vPSG). Case 1, a 30-year-old woman had a 20-yr history of non-injurious arm scratching/rubbing during sleep. vPSG: forearm rubbing against the chin during N2/N3. Two years later she developed restless bladder symptoms and leg movements before sleep onset. Serum ferritin level: 20.7 Intravenous iron therapy resulted in full control of bedtime leg movements, restless bladder symptoms, and nocturnal scratching. Case 2, a 28-year-old married man had a 1.5-yr history of perianal scratching with excoriations/bleeding during sleep, without other parasomnia. Medical and dermatologic evaluations were negative. vPSG: arousal index of 34/hr, with multiple episodes of perianal scratching. Paroxetine, 20 mg with clonazepam as (0.5-1.0 mg) at bedtime induced 50 % efficacy. Case 3, a 26-year-old African-American female had NREM parasomnias, vigorous sleep-related scratching with keloid formation, and major depression. Medical history was negative. vPSG: arousal index: 28/hr, without abnormal behaviors. Multiple sleep latency test (MSLT): mean sleep latency, 3.6 min, no REM sleep. Idiopathic hypersomnia and NREM parasomnias were diagnosed. Sleep-related scratching and NREM parasomnias responded fully to bedtime clonazepam, 0.5 mg. Case 4, a 50-year-old female had longstanding injurious sleep-related scratching, sleep terrors, and sleep bruxism. vPSG: 55 % sleep efficiency; arousal index: 25/hr, without abnormal behaviors or apneas. MSLT: no objective sleepiness. These cases of sleep-related scratching disorder represent a heterogeneous presumed variant of NREM arousal disorder with various comorbidities, and with full/partial control from diverse therapies.