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Table 1 Summary of phenomenology, pathophysiology, main clinical features, investigations and treatment of spinal-generated movement disorders (SGMDs)

From: Spinal-generated movement disorders: a clinical review

SGMDs Phenomenology Pathophysiology Main clinical features Investigations Treatment
Spinal segmental myoclonus (SSM) Myoclonus • Loss of inhibition of spinal interneurons → hyperexcitation of anterior horn cells • Jerks of 1 or 2 limbs
• Rhythmic or semi-rhythmic
• Generally not stimulus-sensitive
• MRI of the spinal cord • Rx of specific etiologies.
• CLZ, VPA or LVT for symptomatic Rx
Propriospinal myoclonus (PSM) Myoclonus • Possible defects in propriospinal pathways (not yet proven in humans)
• Psychogenic etiology also proposed
• Slow truncal jerking
• Flexion more common than extension
• Stimulus-sensitive, but longer latency than cortical myoclonus
• MRI of the spinal cord
• EP testing
• Rx of specific etiologies in 2° forms
• CLZ or VPA for symptomatic Rx
Orthostatic tremor (OT) Tremor • Unclear
• Proposed tremor generators: brainstem, thalamus, and spinal cord
• 1° and 2° (OT-plus) forms exist
• 13–18 Hz; in legs and trunk
• Present when standing but not walking
• Subjective unsteadiness; tremor may not be visible
• Improved when lightly touching a table or wall
• “Helicopter sign”
• EP testing
• MRI of the brain or spinal cord (if exam is abnormal and 2° OT is suspected)
• Mainly CLZ or GBP
• L-dopa or DA may be used in cases with concomitant parkinsonism
Paroxysmal tonic spasms in multiple sclerosis (MS) and neuromyelitis optica spectrum disorders (NMOSD) Dystonia • Ephaptic transmission between partially-demyelinated axons anywhere in central nervous system
• Common locations: contralateral cerebral peduncle, internal capsule, and spinal cord
• Painful; involves unilateral arm or leg
• Typically non-kinesigenic
• Last several seconds to minutes
• May involve ipsilateral face
• Aggravated by hyperventilation
• Can be initial presentation of MS
• MRI of the brain and spinal cord
• Other MS/NMOSD work-up including CSF studies
• CBZ or acetazolamide
Stiff person syndrome (SPS) and its variants Stiffness • Impaired spinal GABAergic and glycinergic inhibitory circuits → CMUA
• Supraspinal mechanisms proposed
Classic form: stiffness of the trunk and legs, hyperlordotic gait
Stiff limb variant: involves only 1–2 limbs
• Ab testing (serum anti-GAD, anti-amphiphysin; less commonly anti-glycine or GABAA receptor)
• Malignancy work-up
• Rx of specific etiology if any
• Immunosuppressive Rx: steroid, IVIg, and/or PLEX; chronic oral agents such as MMF, AZA and CYC
• BZDs for symptomatic Rx
Progressive encephalomyelitis with rigidity and myoclonus (a variant of SPS) Stiffness, myoclonus • Loss of spinal inhibitory interneurons
• Brainstem also involved
• Myoclonic jerks of the trunk, limbs and cranial muscles
• +/− Nystagmus, oculomotor abnormalities, dysarthria and dysphagia
• Ab testing (serum and CSF anti-GAD, anti-glycine receptor, anti-DPPX)
• MRI of the spinal cord and brainstem
• CSF studies may be required
• Rx of specific etiology if any
• Immunosuppressive Rx as in SPS
Movements in brain death and automatic stepping* Spinal reflexes • Disconnection of supraspinal control → disinhibition of the spinal reflexes
• Some proposed released phylogenetically primitive patterns
• Automatic stepping: spinal automatism from spinal CPG
• 2 types (examples shown)
- Automatisms (abdominal contraction, undulating toe movements)
- Reflexes (after neck flexion, finger pinching or testing Babinski sign)
• Automatic stepping reported in a near brain-dead patient
• Confirmation of brain death (physical exam, apnea testing or TCD, etc.) • Family reassurance
Painful legs-moving toes syndrome (PLMT) Miscellaneous • Unknown
• Proposed mechanism: peripheral nerve pathology → 2° impairment in spinal and/or supraspinal controls, and central sensitization
• Slow 1–2 Hz, athetoid-like
• Involves fingers or toes
• Moves in vertical and/or horizontal planes
• Pain usually the most debilitating symptom
• Painless form present
• Work-up for associated neuropathies or radiculopathies depending on clinical context
• MRI of the spinal cord rarely required
• Rx of concomitant diseases such as neuropathies
• GBP or PGB
• Others (case reports): baclofen, CBZ, BZD, TCA, SCS, epidural block, sympathetic blockade, TENS, BoNT
  1. Summary table of pathophysiology, clinical features, investigations and treatment of SGMDs
  2. *Movements in brain death and automatic stepping are normal findings, not "disorders".
  3. Abbreviations: MRI magnetic resonance imaging, Rx treatment, CLZ clonazepam, VPA valproate, LVT levetiracetam, EP electrophysiologic, primary, secondary, GBP gabapentin, L-dopa levodopa, DA dopamine agonist, CBZ carbamazepine, CSF cerebrospinal fluid, GABA gamma-aminobutyric acid, CMUA continuous motor unit activity, Ab antibody, GAD glutamic acid decarboxylase, IVIg intravenous immunoglobulin, PLEX plasma exchange, MMF mycophenolate mofetil, AZA azathioprine, CYC cyclophosphamide, BZD benzodiazepine, CPG spinal central pattern generator, TCD transcranial Doppler ultrasound, PGB pregabalin, TCA tricyclic antidepressants, SCS spinal cord stimulation, TENS transcutaneous electrical nerve stimulation, BoNT, botulinum toxin injection