Lambert-Eaton Myasthenic Syndrome

What is Lambert-Eaton Myasthenic Syndrome?

This is a disorder also referred as LEMS. It involves the faulty communications between nerves and muscles which leads to weakness of the muscles. This syndrome is a very rare “autoimmune disorder”.


Individuals who develop LEMS are normally over 40 years of age, although it can develop at any age. This diagnosis is normally defined with blood tests and electromyography which also distinguishes it from myasthenia gravis which is a closely related autoimmune neuromuscular disease.

If the disorder is linked with cancer, the treatment of the cancer symptoms will often get rid of the symptoms of LEMS. Additional treatments can include azathioprine, steroids, and circulatory immunoglobulin that subdues the immune system and pyridostigmine and 3, 4-diaminophyridine, which enhances the neuromuscular communication. Sometimes, plasma interchange is needed to eradicate the antibodies.

LEMS is estimated to affect four (4) to ten (10) cases per million individuals, or approximately 2000 to 4000 patients in Europe and 1200 to 3100 patients in the United States and is considered a rare condition.

Symptoms

The symptoms and signs of this syndrome consist of:

  • Weakness in arms and legs
  • Physical exercise and high temperatures may worsen symptoms
  • Problems climbing stairs and rising from sitting position
  • Some individual may have vision that is double
  • Weakness of bulbar muscles that supply the throat and mouth
  • Eyelids drooping
  • Problems swallowing but usually only together with weakness of the leg
  • Weakness of respiratory muscles may occur in advanced stages of the disease
  • Problems with coordination – ataxia
  • Dry mouth
  • Disruption of the autonomic nervous system
  • Constipation
  • Impaired sweating
  • Blurred vision
  • Orthostatic hypotension –blood pressure falls on standing, possibly leading to blackouts
  • Impaired sweating
  • Metallic taste in the mouth

On neurological exam, weakness is established with the normal testing of power but is often less severe than expected on the basis of the symptoms. Strength will further improve with repeated tests example power improves on repeated hand grip. This is a sensation denoted to as “Lambert’s sign”. At rest, reflexes are normally reduced; with use of muscle, reflex strength is increased – a LEMS distinctive sign. The “pupillary light reflex” can be sluggish.

When LEMS is linked with cancer of the lung, there might not be any indicative signs of cancer at the time, such as coughing blood, cough, and loss of weight. It has been described that LEMS linked with lung cancer is additionally severe.

Causes

LEMS happens when the cells of the nerves do not release enough of the chemical referred to as acetylcholine. This is the chemical sends impulses between the nerves and the muscles.

This causes weakness of the muscle as well as other symptoms that are similar to myasthenia gravis. But, as muscle continues to contract or tense up, acetylcholine may accumulate in larger amounts for the strength to slightly improve. Rather than getting weaker as it continues to contract frequently, it will become stronger for a short time.

LEMS can also be linked with autoimmune diseases, such as hypothyroidism or diabetes Type 1. Myasthenia gravis also might occur in the company of tumors. Individuals with MG with no tumor and individuals with LEMS with no tumor have comparable genetic deviations that seem to incline them to these diseases.

Treatment

There is currently no cure existing for LEMS. The treatment that is most effective when cancer is present is extermination of the cancer though other drugs have been used with some success. Management thru medication is concentrated at dismissing the symptoms. Drugs may be used to discharge more of the neurotransmitter that these muscles are not receiving enough of. There are other drugs that may be taken that also slow down the production of the antibodies that are created. These antibodies are what at the beginning cause the muscles to cease contracting. Another option of treatment is plasmapheresis. With this procedure, the blood plasma is removed and replaced.

Treatment of LEMS with azathioprine, corticosteroids and 3, 4-diaminopyridine has not yet gained much success regarding completely curing this condition. Plasma exchange or intravenous immunoglobulin may be tried and have some success in aiding treatment of this medical condition.

Diagnosis

LEMS is a syndrome of neuromuscular junction communication with the main demonstration of muscles that are weak. Information of elusive clinical features as well as lab anomalies that go together with LEMS allows for the early identification of the disorder. Early identification is especially significant because of its strong link with small cell lung cancer. LEMS can transpire at any point in the course of cancer, but the earlier it is found it serves as a marker for early disease.

Prognosis

The prognosis depends mainly on the nature and presence of any underlying cancer or the severity of any other associated autoimmune disease.

LEMS often leads to timely discovery of SCCL so individuals with LEMS and SCCL often have an improved prognosis. If LEMS has been indicative for two (2) years as well as having no underlying cancer, the LEMS is most likely of autoimmune cause. Prognosis is at that time established on how severe the dysfunction is, as well as the severity and existence of other autoimmune situations.

Extreme severity is typically recognized within months of the development of the first symptoms. Relapse, attack or flare-up can occur as secondary to undercurrent illness as well as medications that affect neuromuscular transmission. Most patients find that therapy can aid to get rid of symptoms partially; however, the usual symptoms advance over time.

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