Lambert-Eaton synd rome can affect people of any age (even children), but typically occurs in people over 40 years of age. The exact incidence of Lambert-Eaton syndrome is not known, but it is estimated to occur in about three in a million people.

Causes of Lambert-Eaton syndrome

The pathomechanism of Lambert-Eaton syndrome is based on the formation of specific antibodies. The immunoglobulins associated with this condition are directed against one of the nerve cell components, which are so-called voltage-gated calcium channels. When antibodies target the aforementioned structures, they disrupt their function, which is what causes the symptoms of Lambert-Eaton syndrome.

The influx of calcium ions into the nerve cell, which is mediated by these channels, is necessary for the release of neurotransmitters (acetylcholine) from synaptic vesicles. When antibodies bind to calcium channels, calcium influx into the neurons is impaired, thus reducing the release of acetylcholine into the synaptic space. These channels are mainly present at neuromuscular synapses, but they also exist in autonomic structures and in the cerebellum, which is why the symptoms of Lambert-Eaton syndrome centre around dysfunction in these three parts of the nervous system.

The majority, up to 60%, of all Lambert-Eaton syndrome patients have some form of malignancy. This is most often small-cell lung cancer, but the syndrome may also accompany other cancers, such as breast or prostate cancer. Sometimes, the condition is associated with autoimmune diseases such as hypothyroidism or diabetes.

It should be noted that calcium channel antibodies are indeed a cause of Lambert-Eaton syndrome, however, not in all patients. It is estimated that these immunoglobulins occur in 60 to 90% of patients with Lambert-Eaton syndrome.

photo: panthermedia

What are the symptoms of Lambert-Eaton syndrome?

In Lambert-Eaton syndrome, the predominant symptom is muscle weakness. Most often, the problem affects the muscles of the proximal (closer to the trunk) limbs; typically, more significant disorders affect the lower limbs. Patients therefore experience, for example, difficulty climbing stairs, and they may also have difficulty standing up from a sitting position. Other symptoms of Lambert-Eaton syndrome include: autonomic dysfunction (dry mouth, erectile dysfunction, orthostatic hypotonia and constipation, and sweating disorders), cerebellar disorders (mainly in the form of ataxia), and weakness of the so-called bulbar muscles (the muscles of the mouth and throat, whose weakness can lead to speech and swallowing disorders).

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Lambert-Eaton syndrome diagnosis

A patient with symptoms of Lambert-Eaton syndrome is most likely to be referred to a neurologist. The specialist in this field will first carry out a neurological examination, in which it is possible, for example, to identify weakened tendon reflexes. There is a need to differentiate the syndrome from myasthenia gravis - a detailed medical history is important in this case; however, Lambert-Eaton syndrome does have some characteristic features. Well, if the patient moves the weakened muscles for a while (e.g. lifts an upper limb), then there is a temporary improvement in his muscle strength in that part of the body. Electromyographic (EMG) testing is also used in the diagnosis of Lambert-Eaton syndrome.

It has already been mentioned that Lambert-Eaton syndrome often coexists with cancer. Therefore, when a patient is diagnosed with this entity, it is necessary to test for various cancers. Depending on the data obtained from the history, patients may be referred for various investigations, e.g. if there is a significant risk of lung cancer, a Lambert-Eaton syndrome patient may be referred for a CT scan of the chest.

What is the treatment for Lambert-Eaton syndrome?

If a neoplasm is responsible for the Lambert-Eaton syndrome, the therapeutic management in this situation focuses on the treatment of the neoplastic condition in question. The rationale for this treatment is not only that the cancer may be life-threatening for the patient, but also that most patients develop Lambert-Eaton syndrome symptoms after recovery from the cancer.

For the treatment of Lambert-Eaton syndrome itself, mainly pharmacotherapy is used. Patients are given drugs such as:

• 3,4-diaminopyridine,
• glucocorticosteroids,
• azathioprine,
• cyclosporine,
• pyridostigmine.

Sometimes intravenous immunoglobulin preparations and plasmapheresis (a procedure involving plasma exchange) are also used in therapy.

photo: panthermedia

Lambert-Eaton syndrome: why is it worth talking about?

As has been mentioned several times, life-threatening illnesses are sometimes associated with Lambert-Eaton syndrome. This entity is important in that sometimes its symptoms appear long before any cancer-related complaints occur. It is also noted that patients experiencing Lambert-Eaton syndrome with concurrent lung cancer most often do not present with symptoms of that cancer, such as weight loss, coughing or haemoptysis.

There are also patients who develop Lambert-Eaton syndrome and have a very thorough diagnostic procedure, but still fail to detect a cancerous focus. In such situations, regular follow-up is recommended, often even for a relatively long period of time, up to two years.