Lambert Eaton Syndrome

What is Lambert Eaton Syndrome?

The rare medical disorder Lambert Eaton Syndrome is a neuromuscular transmission disorder that may manifest symptoms similar to that of myasthenia gravis. Patients who have this may experience muscle weakness especially in the thigh and pelvic area ^{[1, 2, 3]}.

The Lambert Eaton Syndrome (LES) is an autoimmune disorder where there is a disruption in the transmission at the neuromuscular junction. The medical condition is named after the neurologists Edward Lambert and Lee Eaton. They are the first ones to describe the events in this syndrome in the 1950’s and 1960’s ^{[1, 2, 3, 4]}.

Neurotransmission at the junction should go on smoothly in order to facilitate normal muscle movement. Being an autoimmune condition, the body mistakenly attacks its own tissue as if it was a foreign body. Damage at the neuromuscular junction disrupts the transmission between the nerve and the muscle. This may lead to the weakness of the muscle and tingling in the affected area. About 4 out of 10 patients with this condition are diagnosed with cancer. Usually this cancer is a small cell lung carcinoma although other cancers that may be present are carcinoma of the colon, prostate, stomach, kidney and gallbladder. The prognosis of LES depends on the distribution and severity of the muscle weakness, severity of the autoimmune damage and any underlying malignancy ^{[1, 2, 4, 5, 6]}.

Causes

Being an autoimmune disorder, the antibodies produced by the body’s immune system causes the damage to the nerve cells at the neuromuscular junction. Damaged nerve cells are unable to produce acetylcholine which is essential in the neurotransmission. This will then lead to the presenting symptoms of this condition [1, 2].

Another theory is that since majority of the patient with LES has an underlying malignancy, the body’s effort to fight the presence of the cancer cells also damages the nerve endings and lead to the symptoms of LES ^[4].

Signs and Symptoms

The main symptom of LES is muscle weakness. The weakness may differ in their severity in different parts of the body and may even make activities of daily living difficult to perform. They may experience difficulty in talking, chewing, and swallowing. Due to the weakness of their neck muscles, they may even choke or gag while they are eating. Climbing the stairs or lifting heavy objects may be too taxing for them ^{[1, 2]}.

Other lambert eaton syndrome symptoms are changes in vision, drooping of the head, blood pressure changes especially upon standing quickly and having a dry mouth ^{[1, 2]}.

Diagnosis

Health history and physical examination

The focus of the medical history is to identify any underlying condition on the patient. They may have cancer that they are not aware off. The physical examination will look into the extent and severity of the weakness. Some findings that the physician may see are decreased muscle tone, hypoactive reflexes and muscle weakness that may seem to improve with activity ^{[2, 3]}.

Other Tests

Blood tests may be required by the physician in order to find the antibodies that damages the nerve fibers. Performing an electromyography and a nerve conduction velocity tests will help assess the extent of the condition. The electromyography will be able to test the status of the muscle fibers while the nerve conduction velocity will measure the time of the electrical transmission in the nerves ^{[2, 3]}.

Management

The goal of the management for LES is to identify any possible underlying condition and give symptomatic relief to the patient. If a malignancy is discovered, the patient may need to undergo the required treatment modality for the symptoms to improve ^{[1, 2, 4]}.

Symptom-relief may involve suppressing the patient’s immune system. This is achieved through the use of medications like anticholinesterase and performance of a process known as plasmapheresis. In this procedure, the plasma of the blood is removed from the body and is replaced with either donated plasma or proteins such as albumin. This process will reduce the number of antibodies in the body and reduce the intensity of the symptoms experienced by the patient ^{[1, 2, 3, 4, 5]}.

The manifestations of LES intensify when the patient is warm or having a fever. Avoiding hot showers and baths will help manage the symptoms. The healthcare provider must be contacted once the patient is starting to show flu symptoms in order to manage it right away. Regular exercise and adequate sleep and rest are also seen to assist in symptom management ^[5].

References

1. Stickler, D. (2016, May 6). Lambert-Eaton Myasthenic Syndrome (LEMS). Retrieved from Medscape: http://emedicine.medscape.com/article/
2. Campellone, J. V. (2014, July 27). Lambert-Eaton syndrome. Retrieved from Medline Plus: https://medlineplus.gov/ency/article/000710.htm
3. Gozzard, P. (2012). Lambert-Eaton Myasthenic Syndrome. Retrieved from National Organization for Rare Disorders: http://rarediseases.org/rare-diseases/lambert-eaton-myasthenic-syndrome/
4. The Muscular Dystrophy Association. (2015, December 18). Lambert-Eaton Myasthenic Syndrome (LEMS). Retrieved from The Muscular Dystrophy Association: https://www.mda.org/disease/lambert-eaton-myasthenic-syndrome
5. National Institute of Neurological Disorders and Stroke. (2007, February 13). NINDS Lambert-Eaton Myasthenic Syndrome Information Page. Retrieved from National Institute of
6. Neurological Disorders and Stroke: http://www.ninds.nih.gov/disorders/lambert_eaton/lambert_eaton.htm
7. Johns Hopkins Medicine. (2016). Lambert-Eaton Syndrome. Retrieved from Johns Hopkins Medicine: http://www.hopkinsmedicine.org/