Generalized (generalized) weakness

Complaints of general weakness may conceal such different syndromes as asthenic conditions due to various reasons, pathological muscle fatigue and even true paretic syndromes. A detailed clinical analysis of the entire clinical picture and the weakness itself, its syndromic environment, including somatic, neurological and mental status, is important, which is the key to recognizing the nature of general weakness.

The characteristics of the onset of general weakness and its subsequent course can serve as one of the possible approaches to the diagnostic search algorithm.

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The main causes of generalized weakness

I. Generalized weakness with gradual onset and slow progression:

1. General somatic diseases without direct damage to the neuromuscular system.
2. General somatic diseases with a direct impact on the neuromuscular system.
   1. Endocrinopathies.
   2. Metabolic disorders.
   3. Intoxication (including drug-induced).
   4. Malignant neoplasms.
   5. Diseases of connective tissue.
   6. Sarcoidosis.
3. Myopathies.
4. Psychogenic weakness.

II. Acute and rapidly progressing generalized weakness:

1. Somatic diseases.
2. Myopathy.
3. Current lesions of the nervous system (poliomyelitis, polyneuropathy)
4. Psychogenic weakness.

III. Intermittent or recurrent general weakness.

1. Neuromuscular diseases (myasthenia gravis, McArdle disease, periodic paralysis).
2. Diseases of the central nervous system. (Intermittent compression of the spinal cord by the odontoid process of the second cervical vertebra).

Generalized weakness with gradual onset and slow progression

Patients complain of increasing general weakness and fatigue; they may experience psychological fatigue, decreased performance and lack of desire.

The reasons are:

General somatic diseases without direct involvement of the neuromuscular system, such as chronic infections, tuberculosis, sepsis, Addison's disease or malignant diseases, are among the most common causes of gradually increasing weakness. Weakness is usually associated with specific symptoms of the underlying disease; general clinical and physical examination in these cases is most important for diagnosis.

General diseases with a known direct effect on the neuromuscular system. Weakness in these diseases is often predominantly proximal, especially pronounced in the area of the girdles of the upper or lower limbs. This category includes:

• Endocrinopathies such as hypothyroidism (characterized by cold, pale, dry skin; loss of desire; constipation; thickening of the tongue; hoarse voice; bradycardia; muscle swelling, slowing of the Achilles reflexes; etc.; often accompanied by other neurological symptoms such as paresthesia, ataxia, carpal tunnel syndrome, cramps); hyperthyroidism (characterized by proximal muscle weakness with difficulty rising from a squatting position; signe dutabouret, sweating; tachycardia; tremor; hot skin, heat intolerance; diarrhea; etc.; neurological symptoms such as pyramidal and other signs are rarely noted); hypoparathyroidism (muscle weakness and cramps, tetany, headaches, fatigue, ataxia, seizures, rarely hallucinations and choreoathetoid symptoms are noted); hyperparathyroidism (characterized by true myopathy with muscle atrophy; depression; emotional lability, irritability, confusion; constipation); Cushing's disease, etc.
• Some metabolic disorders, such as glycogenosis (characterized by damage to the heart and liver) or diabetes mellitus.
• Certain types of intoxication and drug exposure may cause slowly increasing general weakness. Chronic forms of alcoholic myopathy develop over weeks or months and are accompanied by atrophy of the proximal muscles. Vacuolar myopathy is observed with chloroquine (delagyl); cortisone, especially fluorohydrocortisone, and long-term use of colchicine may cause reversible myopathy.
• Malignant neoplasms may be accompanied by polymyositis, or simply generalized weakness.
• Connective tissue diseases, especially systemic lupus erythematosus and scleroderma, in which muscle symptoms are associated with polymyositis, are important causes of slowly progressive general weakness.
• Sarcoidosis. Patients usually complain of general weakness, malaise, poor appetite, weight loss. In addition, sarcoid granulomas in skeletal muscles and tendons have been described, which manifests itself in even greater muscle weakness, less often myalgia.

Many true myopathies, such as the hereditary muscular dystrophies, can lead to generalized weakness as the disease progresses.

Psychogenic weakness is usually observed in the picture of polysyndromic psychogenic disorders (functional neurological stigmas, pseudo-seizures, speech disorders, dysbasia, paroxysmal disorders of various types, etc.), facilitating clinical diagnosis.

An ac-casuistic observation is that spastic tetraplegia (tetraparesis) is described as the first (initial) manifestation of Alzheimer's disease, proven by post-mortem pathomorphological examination.

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Acute and rapidly progressive generalized weakness

In these cases, the proximal muscles are also predominantly involved. Possible causes:

Somatic diseases such as hypocalcemia of various etiologies can lead to widespread severe weakness within a few hours.

Myopathies, especially acute paroxysmal myoglobinuria (rhabdomyolysis) (characterized by muscle pain and red urine); myasthenia gravis in its rare generalized form and in the symptomatic form due to penicillamine therapy (Myasthenia gravis is characterized by increasing weakness with muscular work, and the patient tires easily, but the condition improves after rest and in the morning); polymyositis (often accompanied by red-purple spots on the skin, muscle soreness and predominantly proximal weakness).

Existing (current) lesions of the nervous system. More or less generalized weakness may result from infectious lesions of the anterior horn cells (neuronopathy), such as poliomyelitis (weakness without loss of sensitivity, fever, areflexia, changes in the cerebrospinal fluid), tick-borne encephalitis, other viral infections, intoxications, AIDP (Guillain-Barré polyradiculopathy) are usually accompanied by distal paresthesias and some sensory changes. Rare acute polyneuropathies such as porphyria (abdominal symptoms, constipation, seizures, tachycardia, photosensitivity of urine) also lead to weakness with minimal sensory changes.

Psychogenic weakness sometimes manifests itself as an acute loss of muscle tone (falling spells).

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Intermittent or recurrent general weakness

The following diseases should be included in this category:

Neuromuscular diseases, especially myasthenia gravis (see above) and muscle phosphorylase deficiency (McArdle's disease), which is characterized by hypokalemic paralysis, appearing together with pain and weakness during prolonged muscle tension. Paroxysmal myoplegia (familial periodic hypokalemic paralysis) is characterized by the development of generalized weakness and flaccid paralysis (in the arms or legs, more often tetraparesis, less often hemi- or monoparesis) with loss of tendon reflexes within a few hours. Consciousness is not impaired. Provoking factors: night sleep, heavy meals, excessive physical exertion, hypothermia, medications (glucose with insulin, etc.). Duration of attacks is several hours; frequency - from isolated during life to daily. Myoplegic syndromes have been described in thyrotoxicosis, primary hyperaldosteronism and other conditions accompanied by hypokalemia (gastrointestinal diseases, urethrosigmoidostomy, various kidney diseases). There are also hyperkalemic and normokalemic variants of periodic paralysis.

Diseases of the central nervous system: intermittent compression of the spinal cord by the odontoid process of the second cervical vertebra, leading to intermittent tetraparesis; vertebrobasilar insufficiency with drop attacks.

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