J Korean Neurol Assoc.  1995 Mar;13(1):151-156.

A Case of Paramyotonia Congenita

• Yoon YC
• Chang SH
• Ham DS
• Lee KK
• Kwon OS
• Kim DE
• Lee KW

Abstract

Paramyotonia congenita (PMC), an autosomal dominant non-progressive muscle disorder, is characterised by cold-induced stiffness followed by muscle weakness. The weakness is considered to be caused by a dysfunction of the sodium channel in muscle fiber. We report a 37-year-old male patient with PMC, complaining of episodic myotonia and motor weakness on cold exposure. In this patient, we performed clinical and neurological examination, electrophysiologic examination and muscle biopsy. On electrophysiologic study, needle EMG showed spontaneous myotonic discharges at room temperature but disappeared after cooling. Amplitude of compound action potential in abductor pollicis brevis muscle decreased significantly after cooling the tested extremity. Muscle biopsy showed a minimal variation of muscle fiber diameters, internal nuclei, chained nuclei, occasional atrophic fibers in vastus lateralis muscle. His mother, his son, three of six siblings, and five of eleven nephewes are affected with same symptomes.

Keyword

paramyotonia congenital myotonic discharge; cold-induced stiffness

MeSH Terms

Action Potentials
Adult
Biopsy
Extremities
Humans
Male
Mothers
Muscle Weakness
Muscular Diseases
Myotonia
Myotonic Disorders*
Needles
Neurologic Examination
Quadriceps Muscle
Siblings
Sodium Channels
Sodium Channels