Lambert-Eaton syndrome is an autoimmune disease caused by damage to the presynaptic membranes of nerve motor endings. Pathology is associated with malignant neoplasia and autoimmune deviation. The main manifestation of this syndrome is excessive fatigue along with a decrease in muscle strength, expressed mainly in the upper leg. The diagnosis depends on a neurological examination and electroneuromyography data. Therapy for Lambert-Eaton syndrome (according to the ICD code - G73.1) consists in removing the tumor (if it is detected), performing immunosuppressive treatment and plasmapheresis sessions. In addition, pharmacological drugs are often prescribed to facilitate the passage of a nerve impulse along the nerve muscle synapse.
The basis of MSLI and myasthenia gravis are two opposed to each other in the synapse of the neuromuscular transmission defect, pre- and postsynaptic, respectively, which are combined by the autoimmune nature of pathological processes. The pathogenesis of MSSL, as indicated above, is due to a violation of the quantum secretion of acetylcholine from the axon presynaptic membrane. In myasthenia gravis, the main pathogenetic target for antibodies are nicotinic acetylcholine receptors (AChR) of the postsynaptic membrane of the striated muscle (acetylcholine reception defect).
Description
Lambert-Eaton syndrome was studied in detail by American researchers, in whose honor he received his eponymous name. This is a myasthenic disease associated with autoimmune and neoplastic processes in the body. The age of those affected can range from twenty to seventy years, but people over forty years of age most often suffer. Initially, this syndrome was diagnosed mainly in men, and against this background, the gender ratio was five cases of the disease in the stronger sex to one fixed ailment in women. True, modern observations of specialists in the field of neurology have shown a decrease in this difference.
According to various sources, the described syndrome acts as a paraneoplastic disease in fifty to seventy-five percent of patients. In particular, it is often found in men (approximately seventy percent of cases), and rarely enough in women. The vast majority of all neoplasias diagnosed with this syndrome are small cell lung oncology. Moreover, the symptoms of myasthenic syndrome can be several years ahead of the detection of tumor processes. In some situations, the disease in question is combined with other paraneoplastic syndromes, for example, with paraneoplastic polyneuropathy.
The causes of the disease
Lambert-Eaton syndrome can develop against the background of malignant neoplasia (cancer of the lungs, stomach, ovaries, prostate, reticulosarcoma, etc.) or an autoimmune process (with rheumatoid arthritis, Sjogren's disease, autoimmune thyroiditis). Autoimmune mechanisms are the pathogenetic substrate of the disease. Ninety percent of patients have antibodies to calcium channels that enter the structure of tumor cells and the ends of nerve motor fibers.
The causes of Lambert-Eaton syndrome are not fully understood. Presumably, the main target of autoimmune attack is the presynaptic membrane of the nerve muscle synapse. Its defeat leads to a decrease in the degree of release of acetylcholine, which is a mediator of neural transmission. The result is a violation of the process of passage of excitation from nerve fibers to muscle tissue, which clinically can be manifested by fatigue and weakness.
Symptoms of Lambert-Eaton Syndrome
The basis of the clinical picture of the disease in question is the presence of increased fatigue and weakness of skeletal muscles along with the prevailing pathology in the upper limbs (hips and pelvic girdle). Patients, as a rule, complain about the presence of weakness in the legs and shakiness, this is especially noticeable when climbing stairs and against the background of prolonged walking.
In addition, patients may experience discomfort in the back and neck along with myalgia, paresthesia in the distal extremities, autonomic disorders (dry mouth, decreased tear production, development of distal hyperhidrosis and orthostatic arterial hypotension). A typical duck paretic gait. A decrease in tendon reflexes is observed.
A distinctive feature of the described Lambert-Eaton syndrome is a slight increase in muscle strength in the process of motor activity, in contrast to myasthenia gravis, against which any movements lead to aggravation of weakness. In some patients, a noticeable omission of the upper eyelids may occur. Among other things, this syndrome is characterized by oculomotor disorders along with diplopia and swallowing disorders, although this is rarely observed.
Diagnosis of Lambert-Eaton syndrome
The diagnosis is made by neurologists based on complaints, and in addition, starting from a neurological examination and the result of electroneuromyography. As part of the neurological status, tetraparesis is identified with a special emphasis in the proximal leg. Hyporeflexia is quite likely along with mild dysmetria when performing a coordinator test. A slight decrease in the palatine and pharyngeal reflexes is not excluded.
Electroneuromyography determines a decrease in the amplitude of the resting action potentials. A temporary increase in the M-response with arbitrary muscle contraction or against the background of rhythmic electrical stimulation of a nerve with a frequency of over 10 Hz (the so-called working-in phenomenon) can also be recorded. When stimulated with a frequency of 3 Hz, a decrease in the height of the M-response is observed, which is typical for myasthenia gravis. An electrophysiological study differentiates this syndrome from myasthenia gravis, polymyositis, myopathy, and other nervous pathologies.
Given that it is very likely that this disease has developed as a paraneoplastic syndrome, a wide examination of patients for the detection of neoplasia is recommended. Carry out a blood test for tumor markers, as well as a number of the following procedures:
- Performing computed tomography of the chest.
- Implementation of magnetic resonance imaging of the brain.
- CT or MRI of the spine.
- Performing an ultrasound analysis of the thyroid gland.
In the absence of results (when there is no neoplasia), a repeated examination is indicated with an interval of six months. In order to confirm the autoimmune nature of the disease, an immunological study is prescribed.
Consider in more detail the treatment of Lambert-Eaton syndrome.
What drugs are used as part of therapy?
In the event that the disease has an autoimmune nature, then the treatment in most situations consists in drug therapy, which includes the use of the following drugs:
- Reception of oppressive immune system glucocorticosteroids.
- The use of drugs that provoke the production of acetylcholine (we are talking about acetylcholinesterase inhibitors like "Pirdostigmine" and "Ipidacrine").
- Reception of potassium salts.
- Carrying out pulse therapy, which consists in the use of hormones, which are administered to patients initially in the maximum amount, and then each time lower the dosage.
Taking certain medications for Lambert-Eaton syndrome, which provoke the production of acetylcholine, is associated with a certain risk, which consists of side effects, for example:
- The appearance of convulsive processes.
- The occurrence of bradycardia.
- Presence of excessive salivation.
- Narrowing of the pupils along with the development of cramping in the stomach or in the intestine.
Therefore, the dosage of such drugs should be selected and adjusted only by a doctor.
Syndrome treatment
In the presence of paraneoplastic origin of this rare autoimmune disease, treatment is based on the elimination of tumor processes. If tumor therapy is successful, then, as a rule, symptom regression is observed. In the case of the autoimmune genesis of the disease, symptomatic therapy is carried out with pharmaceutical preparations that inhibit the immune system. Mostly used, as noted above, glucocorticosteroids. A good effect is demonstrated by plasmapheresis, which allows you to filter out the blood antibodies that circulate in it.
In order to facilitate muscle conduction, acetylcholinesterase inhibitors, acting as pharmaceuticals that facilitate nerve transmission through the accumulation of acetylcholine in the synapse, are included in the treatment regimen. These drugs include "Pyridostigmine" with "Ipidacrine." In some situations, there is an improvement when using Guanidine, which facilitates the release of acetylcholine using nerve endings.
True, Guanidine was not widely used due to its high toxicity with a side effect on the kidneys and bone marrow. A less toxic drug with a similar effect is Diaminopyridine. Its use may be accompanied by the appearance of paresthesia, diarrhea, increased bronchial secretion and tachycardia. Despite the fact that the effectiveness of this medicine has been clinically proven, to date it is used only in specialized medical centers. Next, let's talk about prevention methods.
Preventive measures and possible consequences
The consequences of the syndrome in question can develop in the absence or on the background of untimely treatment of this ailment. They can be manifested in the development of a myasthenic crisis, which is very dangerous for the life and health of the patient. In the event of such a crisis, the heart may stop in patients, which leads to death. It is very difficult to prevent this disease, as it can develop suddenly. But in order not to aggravate the condition of the patient, one must adhere to the following doctoral recommendations:
- Control physical activity, eliminating excessive stress.
- Exclude prolonged exposure to direct sunlight.
- It is strictly forbidden to take certain medicines based on magnesium and some other medicines, which the doctor will definitely warn the patient about.
So, this syndrome is a rare and unpleasant disease, which in most cases develops together with malignant neoplasms. Therefore, one should pay attention to this when performing diagnostics of the main pathology.
Below is a brief instruction for the use of "Ipidacrine" used to treat the disease.
Use of Ipidacrine
The tool is a drug that is used for any violation of the nervous peripheral system. It has found wide application in the field of obstetric practice, neuropathology and surgery. When appointing it, it is necessary to study the instructions for use with Ipidacrine, since it has a number of limitations. This medication is one of the main drugs in the treatment of the syndrome we describe.
Composition and form of release
The medication is a solution for intramuscular administration and is also suitable for subcutaneous administration. The tool can be presented in tablet form. In each specific situation, the doctor individually determines the appropriateness of prescribing a particular format of the drug.
This medication is prescribed in various situations. For example, it is very effective for polyneuropathy, neuritis and polyneuritis, myasthenia gravis and myasthenic syndrome, bulbar palsy and paresis in the rehabilitation period, multiple sclerosis, Alzheimer's disease, encephalopathy, brain injuries of varying severity and against the background of disturbances in cerebral circulation. But as noted earlier, this drug is especially useful if there is a clinical picture of Lambert-Eaton syndrome.
Finally
Thus, weakness along with excessive muscle fatigue does not always indicate physical exhaustion of the human body. Such symptoms are sometimes the main sign of severe ailments. For example, pathologies such as Eaton and Lambert syndrome. This ailment is usually reflected in the lower extremities and can be accompanied by various myalgia. In order not to aggravate the described disease, doctors are strongly advised to adhere to prevention tips and try in every possible way to avoid excessive muscle fatigue.