Lambert-Eaton-Rooke Syndrome
| Classification according to ICD-10 | |
|---|---|
| G73 * | Diseases of the Neuromuscular Synapse and Muscle in Diseases Classified Elsewhere |
| G73.1 * | Eaton-Lambert Syndrome |
| C80 + | Malignant neoplasm without specifying the location |
| ICD-10 online (WHO version 2019) | |
The Lambert-Eaton-Rooke syndrome , also called Lambert-Eaton syndrome (LES), pseudomyasthenia , pseudomyasthenic syndrome and engl. Lambert-Eaton myasthenic syndrome (LEMS) is a rare neurological disease whose characteristic feature is a pronounced proximal muscle weakness . In the case of voluntary movements, maximum strength development is only achieved after a few seconds, which then leads to fatigue of the muscles in question with advanced effort.
The cause is a disturbed signal transmission between nerve and muscle with a presynaptic defect. The disease is one of the autoimmune diseases . There are antibodies against the presynaptic calcium channels formed. This hampers the release of neurotransmitters , which disrupts the transmission of nerve signals to the muscle cells .
The syndrome was named after the American doctors Lealdes McKendree Eaton , Edward Howard Lambert and Edward Douglas Rooke . They were the first to report comprehensively on this disease in 1956 after diagnosis and electrophysiological examinations.
The LES, together with myasthenia gravis and congenital myasthenic syndrome, is one of the myasthenic syndromes.
Emergence
The B lymphocytes of the affected person form antibodies against the presynaptic calcium channels on the neuromuscular end plates , the switching point between nerves and muscles. The antibodies are directed against voltage-dependent calcium channels of the P / Q type. This hinders the release of acetylcholine and only weakens nerve stimuli that are transmitted from the nerve to the muscle cell; the muscle reacts sluggishly. If the nerve stimulus lasts for a long time, acetylcholine accumulates in the synaptic gap and muscle strength increases to the usual extent (Lambert's sign) .
About 60% of people with LES have a malignant tumor, often small cell lung cancer (SCLC) , occasionally prostate cancer , a thymoma, or a lymphoproliferative disease, e.g. B. a lymphoma . Although the molecular mechanism at the neuromuscular synapse has been precisely elucidated, the trigger for the LES is still unknown today. LES is one of the paraneoplastic syndromes and can occur at an early stage, before the tumor is known. This means that the Lambert-Eaton syndrome can give an initial indication of the existence of a lung tumor and the affected people must be examined accordingly.
No malignant tumor is found in around 40% of patients. This idiopathic form is particularly common in patients under 30 years of age and is often associated with other autoimmune diseases , particularly systemic lupus erythematosus .
Incidence
The incidence of Lambert-Eaton syndrome is 3.4 per million people. Men are two to five times more likely to be affected than women. As women are currently getting more and more lung cancer, the proportion of women with Lambert-Eaton syndrome is also increasing.
Symptoms
Typical is a proximal muscle weakness of the extremities, usually with emphasis on the legs. The thigh with hips and knees is particularly often affected, which is particularly evident when climbing stairs. The trunk muscles are also affected.
Other causes of muscle weakness pronounced proximally are myasthenia gravis and idiopathic inflammatory myopathy (such as polymyositis , dermatomyositis or inclusion body myositis), which occur much more frequently with 150 and 100–200 cases per million, respectively. Diagnosis is often difficult, and up to 21% of patients are initially misdiagnosed.
In addition to the pronounced proximal muscle weakness, it is important that there are no sensitive disorders. The paralysis of the eye muscles typical of myasthenia gravis is also absent , and paralysis of the eyelids (ptosis) is rare.
On the other hand, dry mouth , headaches and cognitive disorders often occur as an indication of involvement of the vegetative nervous system (in more than 90%) and the central nervous system .
Other symptoms can include:
- Constipation
- impotence
- Difficulty swallowing or speaking (dysarthria)
- Accommodation disorders (blurred vision)
- Voiding disorders
- Ptosis (drooping eyelids)
- Hypohidrosis (decreased sweating)
- Hyporeflexia (weakened muscle reflexes )
- Changes in blood pressure
diagnosis
If LES is suspected due to the symptoms described, a neurophysiological test is carried out. As an indication of the muscle weakness, the motor sum action potentials are reduced, even in muscles that are not clinically affected. In the case of high-frequency stimulation of the peripheral nerves or a stimulation after a strong muscular load, the strength temporarily increases significantly ( Lambert's sign ), while in myasthenia gravis a fluctuation and an increasingly lower muscle strength (fatigue) can be observed. However, the accuracy and accuracy of the neurophysiological tests depend on the experience of the examiner.
A tensilon test can also be carried out. This can be positive, i.e. the maximum strength is higher after the administration of tensilon than before, as is also the case with myasthenia gravis .
In addition, laboratory tests may arouse suspicion of Lambert-Eaton syndrome harden: In approximately 85% of patients causing the antibodies to may voltage-dependent calcium channels ( VGCC = voltage gated calcium channel) from the P / Q-type detected.
Upon confirmation of a LES which recommends European Federation of Neurological Societies when no malignant tumor is known to be a computed tomography perform (CT) of the chest, and this should be negative, then a positron emission tomography (PET) or PET-CT perform . 96% of all malignant tumors are found in the first year after the diagnosis of LES.
therapy
If a person has Lambert-Eaton syndrome in the sense of a paraneoplastic syndrome, the underlying cancer is primarily treated. This can often significantly improve the symptoms of LES. If muscle weakness persists, pyridostigmine , intravenous immunoglobulin or 3,4-diaminopyridine (amifampridine) can also be used, but the effectiveness of these agents has not been sufficiently proven in studies.
In idiopathic forms, immunosuppression using glucocorticoids , azathioprine or immunoglobulins can reduce the production of autoantibodies, which leads to an improvement in the symptoms.
A symptomatic therapy can with the potassium channel blockers amifamipridine be addressed. This substance increases the calcium influx (i Ca ++ ) by blocking the potassium outflow (i K + ) and in this way counteracts the effect of the antibodies; the result is an increased acetylcholine outflow, the conduction of excitation and thus the muscle strength are improved.
In addition, plasmapheresis can also reduce the antibody concentration and thus improve the symptoms.
literature
- S1 guidelines for myasthenia gravis and Lambert-Eaton syndrome, diagnostics and therapy of the German Society for Neurology (DGN). In: AWMF online (as of 2012)
Web links
Individual evidence
- ↑ EH Lambert, LM Eaton, ED Rooke: Defect of neuromuscular conduction associated with malignant neoplasms. In: American Journal of Physiology . 1956; 187: 612-613
- ↑ Andrew Engel: Myasthenia Gravis and Myasthenic Disorders. Oxford University Press, New York, 2012, ISBN 978-0-19-973867-0 , pp. 156-173
- ^ Walter D. Conwell, S. Andrew Josephson, Howard Li, Sanjay Saint, William J. Janssen: Weak in the Knees New England Journal of Medicine 2013, Volume 369, Issue 5, August 1, 2013, pages 459-464, doi : 10.1056 / NEJMcps1210293 .
- ↑ in psychoneuro 2003; 29: 113-117, doi: 10.1055 / s-2003-38713 Diseases with disorders of neuromuscular transmission - Katharina Eger (Clinic and Polyclinic for Neurology of the Martin Luther University Halle-Wittenberg, Halle / Saale)
- ↑ Paraneoplastic neuromuscular diseases - uniform federal consensus papers of the muscle centers on behalf of the German Society for Muscular Diseases. V. (DGM) Leading author: Dr. F. Blaes Neurological Clinic Justus Liebig University Am Steg 14 35392 Giessen
| This text is based in whole or in part on the entry Lambert-Eaton Syndrome in Flexikon , a wiki from DocCheck . The takeover took place on April 26, 2006 under the then valid GNU license for free documentation . |