Which physical findings are characteristic of focal muscular atrophy (FMA)?

Updated: Feb 20, 2018
  • Author: Sridharan Ramaratnam, MD, MBBS; Chief Editor: Helmi L Lutsep, MD  more...
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Answer

Signs vary depending on the causative disorder.

  • General physical examination may reveal evidence of arthritis or other deformities.

  • Examination of the cranial nerves may reveal evidence of tongue wasting, which suggests amyotrophic lateral sclerosis (ALS) or other diseases that involve the bulbar musculature.

    • The pattern and distribution of muscle wasting and weakness may localize the lesion to a peripheral nerve or plexus or root. Muscle hypertrophy may be noted in myopathic disorders as well as in neurogenic disorders.

    • Fasciculation may occur in cases of anterior horn or proximal root involvement.

    • Sensation is normal in disorders that affect only the anterior horns, but it may be impaired when the root/plexus/peripheral nerve is affected. The distribution of sensory loss may have a localizing value.

  • The deep tendon reflexes (DTRs) may be brisk or exaggerated in spinal lesions or in ALS.

    • DTRs may be normal in muscle diseases.

    • DTRs may be absent in a root/plexus/nerve lesion.

  • Footdrop gait and inability to walk on the heels reveal weakness of the foot dorsiflexors.

  • Difficulty in walking on the toes and hopping on the toes of one foot are signs of calf muscle weakness.

  • Toe-walking indicates contracture of the Achilles tendon.

  • Limping gait is a sign of unilateral muscle weakness or arthritis involving the lower limb(s).

  • Thickened peripheral nerve(s) and anesthetic skin lesions may suggest leprous neuropathy.

  • Foot deformity implies weakness of the intrinsic muscles of the feet.

  • Deformity or tenderness of the spine reveals diseases of the spinal cord or roots that are secondary to vertebral pathology. Scoliosis may occur in distal SMA.


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