Describe briefly the clinical features, differential diagnosis, initial diagnostic tests and treatments for a patient with suspected acute transverse myelitis.

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College answer

Clinical Features:                                                                                                               [3 marks]

Acute transverse myelitis is a clinical syndrome characterised clinically by rapid onset and progression of motor, sensory and autonomic dysfunction as a result of acute inflammation involving gray and white matter at one or adjacent levels in the spinal cord.

  • History: recent vaccination, travel, recent infection (esp viral). History of motor, sensory or autonomic symptoms including pain, parathesiae.
  • Clinical Findings:
    • Motor weakness, paraparesis.
    • Sensory level
    • Autonomic signs – e.g. incontinence

Differentials (i.e. diagnoses other than those specifically associated with ATM);

[2 marks for any 4 of below]

  1. GBS
  2. Vascular event -Anterior spinal artery syndrome.
  3. Multiple sclerosis (similar but different immunopathogenesis – MS mediated through cell mediated immune aberration, ATM mediated through abnormal humoral immunity)
  4. Acute Compressive myelopathy due to bleed (e.g. AVM) or abscess
  5. Herpes zoster myelitis
  6. Post-polio syndrome (even in countries where polio has been eradicated)
  7. B12 deficiency (usually sub-acute)

Diagnostic work-up;

  • CT spine to rule out compressive myelopathy, bleed
  • MRI brain and spine with gadolinium contrast – MRI findings (T2 signal) may lag clinical findings
  • CSF examination:
    • variable cellular response dependent on sub-aetiology
    • Culture and enterovirus PCR
    • Oligoclonal bands and specific immunology (NMO, ADEM) [2 marks]
  • Blood tests for anti-CNS and systemic auto-antibodies (don’t expect fine print, bonus marks for candidates knowing association of NMO with acquaporin-4 IgG antibodies)
  • Blood for B12 levels
  • ENMG (neurophysiology), if possibility of neuropathy remains.

Note: Must include imaging (either CT scan or MRI) and CSF examination in this section to score full marks.

Specific Treatments to be initiated;                                                                                                               [3 marks]

– should be commenced awaiting definitive diagnosis

  1. Pulse corticosteroids for ADEM, NMO and ATM associated with auto-immune diseases are usual care; trials lacking
  2. Plasma exchange: for ADEM, NMO
  3. IVIG described

Discussion

This question is a welcome evolution of Question 3 from the second paper of 2018, where (again) the trainees were asked to compare Guillaine-Barre syndrome to another lower motor neuron disease. 

Clinical features

  • History and background:
    • Usually occurs as a postinfectious complication
    • Can fall within the spectrum of coexisting MS
    • Can coexist with acute disseminated encephalomyelitis
    • Autoimmune diseases are associated (eg. SLE, scleroderma, etc)
    • Often, very rapidly progressing
    • Weakness nadir is achieved within 4 hours in some cases (though some take as long as 21 days)
  • Examination findings:
    • Power
      • Bilaterally decreased power 
      • Symmetrical
      • Weakness remains at and below the level of the lesion
      • "Pyramidal" preference: flexors of the legs and the extensors of the arms
    • Tone
      • Initially flaccid
      • Later, hypertonic spasticity
    • Reflexes
      • Depressed initially
      • Hyperreflexia subsequently
    • Sensation
      • Sensation is usually absent 
      • There is usually a distinct symmetrical sensory level
    • Cranial nerves
      • Usually, not involved
      • When it forms a part of the MS spectrum, there may be optic neuritis
    • Autonomic dysfunction
      • Usually, no dysfunction, unless the level of the lesion is high
      • High lesions may present with spinal shock

Differential diagnosis

  • Vascular causes
    • spinal cord infarction
  • Infectious causes
    • Polyomyelitis
    • Epidural abscess
    • Herpes zoster
  • Neoplastic causes
    • Spinal canal tumour
  • Drug-related causes
    • B12 deficiency
    • Steroid-induced myopathy
  • Hereditary distal neuropathies
    • Spinobulbar muscular atrophy (Kennedy's disease)
    • genetically heterogeneous distal hereditary motor neuropathies
  • Autoimmune/ immune-mediated diseases
    • Guillain-Barré syndrome
    • multifocal motor neuropathy (MMN)
    • Chronic inflammatory demyelinating polyneuropathy (CIDP)
    • Multiple sclerosis
    • Myasthenia gravis
    • Eaton-Lambert syndrome
    • Myositis and dermatomyositis
  • Iatrogenic causes
    • Critical illness polyneuromyopathy

Initial diagnostic tests

  • Bloods
    • B12 level
    • Aquaporin-4 IgG antibodies
  • Lumbar puncture:
    • Expect to see raised protein and lymphocytosis
    • Test for viruses (zoster and enterovirus) 
    • Also, need culture and gram stain if an infection is still a serious differential
  • Nerve conduction studies
    • Reduced amplitude sensory nerve action potential (SNAP)
    • Pathological F-wave responses
    • Decreased conduction velocity of motor and sensory nerves.
  • Electromyography
    • Reduced amplitude of motor (MUP) action potentials
  • MRI
    • Noncontrast MRI reveals cord oedema at the level of the lesion (but in 40%, looks totally normal)
    • Gadolinium-enhancing signal abnormality extending over one or more cord segments.
    • Lesions occupy most of the transverse diameter of the cord (2/3rds)

Management

  • High dose steroids: though there are no clinical trials, generally people tend to recommend giving 1g/day of methylprednisolone for 3-7 days
  • Plasmapheresis should be offered to those patients who do not respond to steroids: though this recommendation is also extrapolated form the fact that other demyelinating autoimmune diseases benefit from plasmapheresis. Beh et al (2013) recommended  1.5 plasma volumes for 5 treatments over 10 days (i.e. every second day). This should be offered early, within 15 days of diagnosis
  • Cyclophosphamide is recommended occasionally
  • Rituximab has been attempted
  • IV immunoglobulin is not usually recommended, as there is insufficient evidence

References

References

Beh, Shin C., et al. "Transverse myelitis." Neurologic clinics 31.1 (2013): 79-138.

Waters, Patrick, et al. "Aquaporin-4 antibodies in neuromyelitis optica and longitudinally extensive transverse myelitis." Archives of neurology 65.7 (2008): 913-919.