Class I: Any ocular muscle weakness; may have weakness of eye closure. All other muscle strength is normal. | |
Class II: Mild weakness affecting muscles other than ocular muscles; may also have ocular muscle weakness of any severity. A. IIa. Predominantly affecting limb, axial muscles, or both. May also have lesser involvement of oropharyngeal muscles. B. IIb. Predominantly affecting oropharyngeal, respiratory muscles, or both. May also have lesser or equal involvement of limb, axial muscles, or both. | |
Class III: Moderate weakness affecting muscles other than ocular muscles; may also have ocular muscle weakness of any severity. A. IIIa. Predominantly affecting limb, axial muscles, or both. May also have lesser involvement of oropharyngeal muscles. B. IIIb. Predominantly affecting oropharyngeal, respiratory muscles, or both. May also have lesser or equal involvement of limb, axial muscles, or both. | |
Class IV: Severe weakness affecting muscles other than ocular muscles; may also have ocular muscle weakness of any severity. A. IVa. Predominantly affecting limb, axial muscles, or both. May also have lesser involvement of oropharyngeal muscles. B. IVb. Predominantly affecting oropharyngeal, respiratory muscles, or both. May also have lesser or equal involvement of limb, axial muscles, or both. | |
Class V: Defined as intubation, with or without mechanical ventilation, except when employed during routine postoperative management. The use of a feeding tube without intubation places the patient in class IVb. |