Neuromyotonia in hereditary motor neuropathy.

Abstract

Case II2 This 15 year old boy had always been clumsy. Since the age of 10, he had noticed generalised muscle stiffness which increased with physical activity such as walking upstairs, running and skating. For some time, he was aware of difficulty in releasing his grip and his fingers tended to cramp on writing. He had noticed involuntary twitching of his fingers, forearm muscles and thighs at rest and it was more pronounced after a forceful voluntary contraction. Muscle cramping and spontaneous muscle activity were particularly unpleasant when he re-entered the house in the winter, for example, after a game of hockey. Since the age of twelve, he had noticed a tendency to trip. Subsequently he developed bilateral foot drop and weakness of his hands. He denied sensory symptoms and perspired only with exertion.He was muscular with well-developed proximal muscles. This contrasted with moderate wasting and weakness of the wrist and finger extensors, the intrinsic hand muscles and also the peroneal and intrinsic fott muscles. Sensory examination was normal. Deep tendon reflexes were reduced and ankle jerks were absent. The plantar responses were flexor. When he was fully relaxed, brief, repetitive twitching of his fingers and myokymia and fasciculations in the proximal muscles were clearly apparent. After forceful flexion of the fingers, the grip release was slow and delayed, with the appearance of action myotonia, yet percussion of the thenar eminence produced no abnormal muscle contraction. Percussion of the tongue, however, resulted in a focal tonic contraction, lasting several seconds, which subsided into fasciculations. Strong voluntary contraction of his quadriceps was followed for 10 to 30 seconds by a persisting, involuntary contraction of the muscles, which subsided into myokymic activity and fasciculations. The Trousseau sign was positive. Within 10 seconds after inflation of a blood pressure cuff, the fingers began to twitch and by 35 seconds they were drawn into a carpal 1 2 Figure 1 Family tree, only II2 and II5 were affected. Detailed electrophysiological testing and biopsies were performed in I2.

Exome sequencing reveals HINT1 mutations as a cause of distal hereditary motor neuropathy

“…Recessive loss-of-function mutations were recently reported 14 in patients with a rare phenotype of axonal neuropathy with neuromyotonia 15 and CMT. The gene was identified in a family with CMT with neuromyotonia and in a consanguineous family with CMT, but mutations in HINT1 were also observed in rare patients with autosomal recessive or sporadic CMT.…”

Autosomal Recessive Peripheral Neuropathy With Neuromyotonia (Aran-Nm): Description of a Clinical Case Confirmed by a Mutation in the Hint1 Gene

“…Это пред-полагает наличие структурной или функциональной аномалии аксональной мембраны [13]. Нейрональное происхождение нейромиотонии было подтверждено регионарными нейромышечными блокадами с исполь-зованием кураре [14]. Двигательные феномены при нейромиотонии сохраняются во время сна и общей анестезии.…”

“…A. F. Hahn с соавт. было дано подробное кли-ническое, электрофизиологическое описание и пред-ставлена биопсия мышечной ткани брата и сестры с началом нейромиотонии в детстве и прогрессирую-щим двигательным дефицитом в дистальных мышцах верхних и нижних конечностей [14]. При проведении ЭМГ у обоих пациентов были выявлены хроническая моторная нейропатия, денервационно-реиннервацион-ные изменения в мышцах и патологическая спонтанная активность периферических нервов, в мышечных био-птатах -признаки частичной денервации.…”

“…Выявленное у нашего пациента умеренное повыше-ние активности креатинфосфокиназы также часто встре-чается при данном заболевании [9,28] и, по-видимому, связано как с хронической нейрогенной мышечной атро-фией, так и с проявлениями нейромиотонии [14].…”

“…Помимо описанной выше симптоматической коррекции двигательных нарушений и ортопедических деформаций, предпринимаются попытки медикаментозного уменьше-ния выраженности проявлений нейромиотонии. Описано относительно успешное применение антиэпилептических препаратов -блокаторов натриевых каналов дифенил-гидантоина (фенитоина) и карбамазепина, а также анти-аритмических препаратов (токаинида) [14].…”