Clinical record

A 32-year-old woman of European ancestry was referred to a movement disorder clinic for evaluation of mild persistent clawing of the right hand (Figure, A), which had developed over the past year. She had no weakness of the hand or other neurological signs.

The patient had been diagnosed with relapsing remitting multiple sclerosis 4 years earlier, based on clinical features (typical exacerbations), characteristic white matter changes on magnetic resonance imaging scans, and oligoclonal bands restricted to the cerebrospinal fluid. Her condition was managed in a multiple sclerosis clinic. Before her referral, she was in good health between exacerbations of multiple sclerosis.

Since early childhood, the patient had experienced persistent cramping of her hands after their use, particularly in cold conditions. She had difficulty releasing tightly gripped objects, and cramping usually worsened, rather than improved, with ongoing exertion, such as when using clippers to groom a dog (ie, there was no “warm-up” phenomenon). She found it difficult to talk after ingesting cold food or drink, and difficult to open her eyes after jumping into a cold pool. In extremely cold conditions, she experienced widespread cramping of her muscles with clawing of her hands, and a tendency for her toes to curl inwards. These symptoms would typically improve over several hours as her body warmed. As the cramping improved, there was notable weakness of affected muscles. A diagnosis of paramyotonia congenita was suspected after referral to the clinic.