Neuromyotonia
Synonyms and keywords:

# Overview
Neuromyotonia, also known as Isaacs' Syndrome, is spontaneous muscular activity resulting from repetitive motor unit action potentials of peripheral origin.

# Historical Perspective
-  was first discovered by , a , in  during/following .
- In ,  mutations were first identified in the pathogenesis of .
- In , the first  was developed by  to treat/diagnose .

# Classification
-  may be classified according to  into  subtypes/groups:
- Other variants of  include , , and .

# Pathophysiology
- The pathogenesis of  is characterized by , , and .
- The  gene/Mutation in  has been associated with the development of , involving the  pathway.
- On gross pathology, , , and  are characteristic findings of .
- On microscopic histopathological analysis, , , and  are characteristic findings of .

# Causes
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.
Autoreactive antibodies can be detected in a variety of peripheral (e.g. myasthenia gravis, Lambert-Eaton myasthenic syndrome) and central nervous system (e.g. paraneoplastic cerebellar degeneration, paraneoplastic limbic encephalitis) disorders. Their causative role has been established in some of these diseases but not all. Neuromyotonia is considered to be one of these with accumulating evidence for autoimmune origin over the last few years. Some neuromyotonia cases do not only improve after plasma exchange but they may also have antibodies in their serum samples against voltage-gated potassium channels. Moreover, these antibodies have been demonstrated to reduce potassium channel function in neuronal cell lines.

# Differentiating  from other Diseases
-  must be differentiated from other diseases that cause , , and , such as:

# Epidemiology and Demographics
- The prevalence of  is approximately  per 100,000 individuals worldwide.
- In , the incidence of  was estimated to be  cases per 100,000 individuals in .

## Age
- Patients of all age groups may develop .
-  is more commonly observed among patients aged  years old.
-  is more commonly observed among .

## Gender
-  affects men and women equally.
-  are more commonly affected with  than .
- The  to  ratio is approximately  to 1.

## Race
- There is no racial predilection for .
-  usually affects individuals of the  race.
-  individuals are less likely to develop .

# Risk Factors
- Common risk factors in the development of  are , , , and .

# Natural History, Complications and Prognosis
- The majority of patients with  remain asymptomatic for .
- Early clinical features include , , and .
- If left untreated,  of patients with  may progress to develop , , and .
- Common complications of  include , , and .
- Prognosis is generally , and the  of patients with  is approximately .

# Diagnosis
As a result of muscular hyperactivity patients may present with muscle cramps, myotonia-like symptoms, excessive sweating, myokymia and fasciculations. A very small proportion of cases with neuromyotonia may develop central nervous system findings in their clinical course, causing a disorder called Morvan's syndrome and they may also have antibodies against potassium channels in their serum samples. Sleep disorder is only one of a variety of clinical conditions observed in Morvan's syndrome cases ranging from confusion and memory loss to hallucinations and delusions.

# Diagnosis

## Diagnostic Criteria
- The diagnosis of  is made when at least  of the following  diagnostic criteria are met:

## Symptoms
-  is usually asymptomatic.
- Symptoms of  may include the following:

## Physical Examination
- Patients with  usually appear .
- Physical examination may be remarkable for:

## Laboratory Findings
- There are no specific laboratory findings associated with .
- A    is diagnostic of .
- An  concentration of   is diagnostic of .
- Other laboratory findings consistent with the diagnosis of  include , , and .

## Imaging Findings
- There are no  findings associated with .
-  is the imaging modality of choice for .
- On ,  is characterized by , , and .
-  may demonstrate , , and .

## Other Diagnostic Studies
-  may also be diagnosed using .
- Findings on  include , , and .

# Treatment
There is no known cure for neuromyotonia. The long-term prognosis for individuals with the disorder is uncertain. Anticonvulsants, including phenytoin 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.

## Medical Therapy
- There is no treatment for ; the mainstay of therapy is supportive care.
- The mainstay of therapy for  is  and .
-  acts by .
- Response to  can be monitored with  every .

## Surgery
- Surgery is the mainstay of therapy for .
-  in conjunction with  is the most common approach to the treatment of .
-  can only be performed for patients with  .

## Prevention
- There are no primary preventive measures available for .
- Effective measures for the primary prevention of  include , , and .
- Once diagnosed and successfully treated, patients with  are followed-up every . Follow-up testing includes , , and .