Table 10-2. Motor System Examination and Ancillary Studies

  1. Observation
    1. Muscle group size, symmetry; limb and trunk posture (e.g. contractures)
    2. Involuntary movements
      • Adventitious movment disorder (e.g., chorea dystonic posture, tremor, myoclonus, seizure).
      • Fasciculation
      • Myotonia on attempted active movement
  2. Palpation and percussion
    1. Tenderness, consistency (less reliable in differential)
    2. Response of muscle to direct percussion (?myotonia)
  3. Passive resistance to manipulation
    1. Spasticity, rigidity (plastic, cogwheel or perseverative/paratonic)
    2. Hypotonia
  4. Strength
    1. Sampling of distal and proximal musculature of extremities in addition to cranial, neck and trunk muscles (e.g., cranial nerve exam, trepezius and sternomastoids, neck extensors, deltoids, bidceps, triceps, wrist dorsiflexion, grip, interosseous finger spread, abdominals, psoas, quadriceps, hamstrings, triceps surae, tibialis anterior, dorsiflexion of foot and large toe). If weakenss or other indication of motor involvement is observed, more detailed exam is necessary.
    2. Grading of strength:
      • 0 - No evidence of movement (try reinforcement)
      • 1 - Trace muscle contraction
      • 2 - Able to move the limb when gravity is eliminated
      • 3 - Complete range against gravity (but no added resistance)
      • 4 - Complete range against gravity with some resistance
      • 5 - Normal
  5. Coordination
    1. Rapid rhythmic alternating movements (RRAM) of upper and lower limbs (e.g., tapping thumb against index finger, tapping heel on opposite knee).
    2. Finger-to-nose, eyes open and eyes closed, heel-to-shin
  6. Gait
    1. Basic observation - ataxa, spasticity, weakness, apraxia, rigidity in extension or flexion; turning behavior, en-bloc, ataxic, apraxic
    2. To test anterior tibialis and coordination: walk on heels.
    3. Coordiantion: tandem heel-toe, walk backward, hop on one foot at a time
  7. Deep-tendon (myotatic), superficial and pathologic reflexes

Ancillary studies as indicated (see chapter 11)

  1. Electromyography and nerve conduction studies (EMG/NCV)
    1. To differentiate neuronal disease from muscle disease, to differentate axonal from demyelinating neuropathy
    2. To substantiate or rule out neuromuscular junction disorders
  2. Neostigmine or edrophonium tests in myasthenia gravis suspect (e.g., a patient with nontender muscle disease, particularly if he has increasing weakness on exercise or unexplained extraocular muscle or bulbar weakness even if only one or a few muscles are involeved)
  3. Neostigmine IM to enhance fasciculations in anterior horn, ventral root and peripheral nerve disease
  4. Muscle - nerve biopsy
  5. Enzyme studies: creatinine phosphokinase (CPK) elevated in acute and subacute disease of muscle; minimally or not elevated with slowly progressive muscle disease and peripheral or central nervous system disease
  6. Vitamin B12, folate; T3/T4/TSH levels; glucose tolerance; K+; urine porphobilinogen; lead levels
  7. Lumbar puncture
  8. Electroencephalogram
  9. Neuroradiologic studies; skull and spine x-rays; angiography; myelography; cisternography; computerized axial tomography; magnetic resonance imaging
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