What is Neuromyotonia?
Neuromyotonia is a rare neuromuscular disorder caused by continuous signaling of the end regions of peripheral nerve fibers that activate muscle fibers (motor neurons). It develops as a result of both acquired or hereditary diseases. Acquired form is more frequent and is usually caused by antibodies against neuromuscular junction.
Causes of Neuromyotonia:
The most cases of the neuromyotonia are caused by auto-antibodies that affect the points at which the signals from the nerve fiber meet the muscle cell (neuromuscular junction). The small proportion of cases of neuromyotonia is genetic in origin and tends to occur in families. Neuromyotonia of this type is inherited as an autosomal dominant genetic trait.
Symptoms of Neuromyotonia:
The major symptoms, which include progressive muscle stiffness, continuous vibrating or twitching muscles, increased sweating, and delayed muscle relaxation, occur even during sleep or when patients are under general anesthesia. Speech and breathing may be affected if pharyngeal or laryngeal muscles are involved.
Diagnosis of Neuromyotonia:
This disorder is diagnosed based on the patient’s past medical history, physical exam and electromyography (EMG). EMG is used to record electrical activity in the muscles and is abnormal in patients with neuromyotonia. Analysis of cerebrospinal fluid, which can be obtained by lumbar puncture, may help confirm the diagnosis.
Treatment of Neuromyotonia:
There is no cure or specific treatment for this disorder. However, treatments for some of the symptoms are available. Anticonvulsant medications, like phenytoin, low dose acetazolamide, and carbamazepine, usually provide significant relief from the stiffness, muscle spasms, and pain associated with neuromyotonia. Plasma exchange may provide short-term relief for patients with some forms of the acquired disorder. Ongoing research includes looking into other possible treatments like oxygen inhalation and surgery to block motor nerves and sensory nerves that control the muscle unit.
