Table 1

Summary of impairment outcomes

Category Neurological status
I (intact)Normal or no change from premorbid functioning.
Seizures, if recorded, 100% controlled
II (mild)Minimal alteration of tone, power, or reflexes; isolated cranial nerve palsies; mild (MRC 4) weakness or ataxia.
Seizures, if present, >75% controlled
III (moderate)Moderate (MRC 3) weakness or ataxia; multiple cranial nerve involvement.
Seizures, if present, >50% controlled
IV (severe)Severe weakness (<MRC 3) or ataxia; tetraparesis.
Uncontrolled seizures
V (profound)Persistent vegetative state
  • Muscle power is graded using the MRC (Medical Research Council) scale: 0, no visible signs of contraction; 1, visible signs of contraction; 2, limb movement but insufficient power to overcome gravity; 3, sufficient power to overcome gravity but not additional resistance; 4, sufficient power to overcome gravity and additional resistance but not full power; 5, full power.