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Muscle Weakness and Paralysis Symptom

Essentials

  • The underlying causes of muscle weakness or a paralysis symptom may include
    • disorders of the upper or lower motor neuron, or both
    • myoneural junction disorders
    • myopathy
    • endocrinological and metabolic causes
    • psychosocial factors (psychogenic paralysis).
  • It is important to disclose the cause because the different underlying diseases have different aetiologies and therapies.
  • The various causes can at least roughly be differentiated on the basis of clinical examination.

Neurological findings in upper motor neuron (pyramidal tract) disorders

  • Paralyses not confined to the nerve root or peripheral nerve area. Symptoms include muscle weakness, clumsiness, ataxia and sensory disturbance.
  • Frequently includes a positive Babinski's sign
  • Increased tendon reflexes, clonus (extremely hyperactive reflexes, a cluster of rapidly succeeding series of involuntary muscle contractions)
  • Increased muscle tone, i.e. spasticity
  • In the acute variant (shock phase), muscle tone may be decreased and tendon reflexes may be lacking.
  • The patient may also have functional disorders of the cranial nerves as well as neuropsychological symptoms.

Causes originating in the brain

Causes originating in the spinal cord

  • See Diseases of the Spinal Cord.
  • Spinal cord injury
  • Tumours
  • Circulatory disorder (infarction or haemorrhage in the spinal cord)
  • Spondylomyelopathy
  • Syringomyelia
  • Myelitis
  • Motor neuron disease
  • Symptoms
    • Indications of damage to the spinal cord tracts are:
      • paraparesis: muscle weakness in lower extremities
      • tetraparesis: muscle weakness in upper and lower extremities
      • paraplegia
      • tetraplegia
      • also, limb spasticity, often sensory level, bladder dysfunction and in men erectile dysfunction.
    • The following are encountered as indications of localized injury to the spinal cord, such as with syringomyelia or spinal cord tumour:
      • muscle weakness and muscle atrophy of the upper extremities or shoulder area
      • abnormal sensory responses to cold and heat, even when the sense of touch and vibration remain intact (dysaesthesia).

Diseases causing damage to several areas of the central nervous system

  • For example, demyelinating disorders Multiple Sclerosis (Ms)
  • Symptoms include, besides muscle weakness and physical strain-related fatigue, e.g. dysaesthesia, limb coordination disorders and spasticity.

Neurological findings in lower motor neuron disorders

  • Paralyses and sensory disturbances follow the distribution of spinal nerve roots or peripheral nerves.
  • Often (radiating) pain in the same nerve distribution is present.
  • Decreased or absent tendon reflexes
  • Decreased muscle tone
  • Slowly progressing muscle atrophy (over weeks to months)
  • Babinski's sign is negative.

Polyneuropathies

  • See Polyneuropathies.
  • In motor polyneuropathies, muscle strength and tendon reflexes decrease symmetrically, in sensorimotor polyneuropathies appear additionally skin sensation deficits (sock or glove type of distribution), and muscle atrophy develops later in the distal parts of the extremities.

Polyradiculites

  • See Guillain-Barré Syndrome (Polyradiculitis).
  • Generally symmetrical muscle weakness, progressing from the distal parts of the limbs upwards, developing within a few days or over a few weeks' time. The chronic form progresses more slowly. Frequently there is myalgia in the extremities, and tendon reflexes decrease.

Radiculopathies, damage to one or more nerve roots

  • See Radiculopathies.
  • The cardinal symptom is radiating pain. Additionally, paraesthesia and numbness occur in the dermatome innervated by the nerve root.
  • Increasing muscle weakness in the muscles innervated by the affected nerve and decreased segmental tendon reflexes. When the condition has become chronic, muscle atrophy develops.

Damage to neural plexus, plexus injury, plexus neuritis

  • Symptoms include acute myalgia followed by sensory deficits, muscle weakness, decreased tendon reflexes, and muscle atrophy, which appear in one or more segments of the peripheral nerves involved in the plexus.

Nerve entrapment or compression injuries

Concurrent upper and lower motor neuron disorders

  • Amyotrophic lateral sclerosis (ALS) Amyotrophic Lateral Sclerosis (ALS) is the most common motor neuron disease.
  • Symptoms are progressive muscle weakness in voluntary muscles with muscle atrophy and involuntary muscle twitching or fasciculation.
    • In the so-called bulbar form, the symptoms initially centre on the larynx, in which case the first symptoms appear as dysarthria and dysphagia.
  • However, muscle tone may be increased (spastic) and the Babinski's sign may be positive.

Neurological findings of myoneural junction disorders

  • A typical presentation is muscle fatigue intensified by strain.
  • Reflex and sensory functions appear normal.
  • Babinski's sign is negative.

Myasthenia gravis

  • See Myasthenia Gravis.
  • Typically, voluntary muscles tire easily, and the weakness is relieved by rest.

Myasthenic syndrome

  • The myasthenia is more pronounced in proximal muscles, the symptom picture being very similar to that of myasthenia gravis.

Neurological findings in myopathies

  • See also Hereditary Myopathies.
  • Muscle weakness
  • Muscle atrophy, occasionally hypertrophy
  • In some diseases: myalgia, muscle hypotonia
  • Reflexes are often normal.
  • Babinski's sign is negative.

Myopathies

  • These include congenital muscular dystrophies, metabolic myopathies, inflammatory myopathy (myositis), as well as toxic (e.g. alcoholic myopathy) and endocrine myopathies.

Periodic paralyses: sporadic attacks of flaccid paralysis

  • Hypokalaemic: teenage onset
  • Hyperkalaemic: childhood onset
  • Normokalaemic: childhood onset
    • The myasthenic attack is often preceded by muscle strain or a meal high in carbohydrates.

Other endocrinological and metabolic causes

  • Hypo- or hyperthyroidism and hypo- or hypercalcaemia may be associated with muscle weakness.

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