Table 1.

Proposed definitions of SMDs in NMO

SMD	Definition
Flexor tonic spasm	Paroxysmal sustained increase in muscle tone resulting in visible tonic posturing of the affected body part (often the whole limb or part of the limb) in flexion secondary to spinal cord pathology
Extensor tonic spasm	Paroxysmal sustained increase in muscle tone resulting in visible tonic posturing of the affected body part (often the whole limb or part of the limb) in extension secondary to spinal cord pathology
Isometric tonic spasm	Paroxysmal sustained increase in muscle tone that can be felt by the patient and palpated by the examiner, but does not result in visible change in posture (e.g., abdominal wall muscles) secondary to spinal cord pathology.
Unspecified tonic spasm	A tonic spasm not meeting criteria for other spinal movement disorders or not specified in documentation secondary to spinal cord pathology
Paroxysmal focal dystonia	Paroxysmal involuntary sustained muscle contraction of antagonistic muscle groups resulting in abnormal posture (other than simple flexion or extension) secondary to spinal cord pathology
Nonparoxysmal focal dystonia	Persistent (nonparoxysmal) sustained muscle contraction of antagonistic muscle groups resulting in a fixed abnormal posture secondary to spinal cord pathology
Focal/Segmental spinal myoclonus	Sudden, brief (nonsustained), shock‐like focal muscle contraction of one or more adjacent body parts secondary to spinal cord pathology
Propriospinal myoclonus	Sudden, brief, shock‐like, arrhythmic jerks of the trunk, hips, and knees (sparing the head) often in flexion secondary to spinal cord pathology
Tremors of spinal origin	Postural and/or action tremors occurring after spinal cord pathological event in absence of brain/brainstem/cerebellar lesions and personal or family history of essential tremors
Spontaneous clonus	Spontaneous (noninduced) involuntary, rhythmic muscle contractions and relaxations associated with spasticity secondary to spinal cord pathology. It commonly involves the ankle or the wrist and appears in certain positions or with certain movements.