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MYOPATHY - A NEUROLOGICAL ENTITY - AS SEEN IN GENERAL MEDICAL PRACTICE
OP Kapoor
Ex. Hon. Physician, Jaslok Hospital and Bombay Hospital, Mumbai, Ex. Hon. Prof. of Medicine, Grant Medical College and JJ Hospital, Mumbai 400 008.
Symptom of myopathy is generalised muscular weakness. In most cases, there are no specific neurological signs what-so-ever. The deep jerks and the sensations are all normal. The patient cannot get up from lying down position to sitting position, from sitting to standing position, and cannot work at full strength. All these symptoms (and signs) can be witnessed in the doctor’s clinic. The fact is, that these complaints are seen in the following medical disorders as well:
1.Acute viral fevers : Often with high fever a patient has more weakness; but off and on we see patients whose fever is less, but the weakness is out of proportion.
2.All patients of clinical illnesses like tuberculosis and cancer, more so if they have lost weight complain of similar weakness.
3.Patients having mental depression also complain of similar weakness, but on examination all the above three physical signs are absent and the history will elicitate the symptoms of mental depression.
4.All patients having hypertension and IHD, often complain of muscular weakness at some time or the other. Often diuretics are responsible for producing hypokalaemia or hyperkalaemia. HMGCOA Reductase inhibitors (statins), which every patient of IHD receives for life time, are known to cause myopathy, specially of the pelvic muscles and patients may find it difficult to stand up.
5.Respiratory patients : All asthma patients, who are on oral steroids can develop myopathic weakness. Patients who are using steroid inhalers in large doses and do not gargle and rinse, can develop myopathic weakness of the laryngeal muscles affecting the voice.
6.COPD patients often complain of muscular weakness related to anoxia, and their SPO2 levels will be markedly low, while patients of bronchogenic carcinoma can develop a real clinical picture of myopathy.
7.Patients having metabolic diseases : In females, osteomalacia is the most common cause in medical practice, where the women complain of marked weakness and inability to stand up from sitting position (specially in the toilet) and while taking bath.
8.Patients having severe uncontrolled diabetes mellitus, also complain of similar weakness.
9.Patients having renal failure : All patients who develop acute or chronic renal failure invariably complain of myopathic weakness, the biological causes of which are numerous.
10.Electrolyte imbalance, acid base imbalance and anaemia contribute to myopathic weakness.
11.Patients having endocrine diseases, very often complain of myopathic weakness.
12.Hyperthyroid patients complain of the above symptoms, more often than hypothyroid patients of the above symptoms.
13.Patients having adrenal gland disease in the form of Cushing’s syndrome or Addison’s disease will also have severe myopathic weakness.
14.Electrolyte disturbances, often seen in patients having gastro-enteritis, food poisoning, vomiting and diarrhoea due to other causes, can cause myopathic weakness.
Thus, excess or low sodium, excess or low potassium, alkalosis or acidosis can all lead to myopathic weakness.
Finally, Iatrogenic causes : The list of drugs which can produce muscular weakness (starting from most commonly used betablockers which patients are taking for life time) is very long.
Next time, when you see a patient complaining of myopathic weakness, do not jump to neurological causes of myopathies, polymyositis and myasthenic myopathic weakness. All these cases are very rare as compared to the above medical causes and even if the neurological examination is done, it will reveal nothing at all.
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