- Published on
Infectious disease and microbiology – Myelitis
Myelitis is an inflammatory condition of the spinal cord caused by infection or involvement of adjacent tissues, leading to neurologic dysfunction affecting motor, sensory, and autonomic systems.
The epidemiology varies widely depending on the underlying infectious cause. It can occur in both immunocompetent and immunocompromised individuals, although the latter are at higher risk.
Risk Factors
Inflammation may involve:
Etiology
A wide range of infectious agents can cause myelitis:
Viral causes (most common):
History:
Transverse Myelitis:
Laboratory Tests:
Noninfectious causes include:
Targeted antimicrobial therapy based on cause:
Myelitis is an inflammatory condition of the spinal cord caused by infection or involvement of adjacent tissues, leading to neurologic dysfunction affecting motor, sensory, and autonomic systems.
The epidemiology varies widely depending on the underlying infectious cause. It can occur in both immunocompetent and immunocompromised individuals, although the latter are at higher risk.
Risk Factors
- Immunocompromised state (e.g., HIV, malignancy, steroid use)
- Vaccination against poliomyelitis and varicella-zoster virus (VZV)
Inflammation may involve:
- Entire cross-section of the spinal cord → transverse myelitis
- Focal segments → localized myelitis
- Nerve roots involvement → radiculomyelitis
Etiology
A wide range of infectious agents can cause myelitis:
Viral causes (most common):
- Herpes viruses (HSV, EBV, VZV, CMV, HHV-6)
- HIV (vacuolar myelopathy)
- HTLV-1 (tropical spastic paraparesis)
- Influenza virus
- Enteroviruses (coxsackie, echovirus, enterovirus 70/71)
- West Nile virus
- Mycoplasma pneumoniae
- Lyme disease (Borrelia burgdorferi)
- Syphilis (posterior column involvement – tabes dorsalis)
- Tuberculosis (spondylitis, tuberculomas)
- Leptospirosis
- Aspergillus, Coccidioides, Blastomyces
- Schistosomiasis
- Neurocysticercosis
- Epidural abscess causing spinal cord compression
History:
- Rapid onset (hours to days)
- Motor weakness (often bilateral)
- Sensory disturbances
- Bladder and bowel dysfunction
- Back pain or radicular (dermatomal) pain
Transverse Myelitis:
- Sensory level on the trunk
- Loss of motor and sensory function below lesion
- Reflexes initially decreased, later hyperactive
- Asymmetric weakness
- Fasciculations and muscle atrophy
- Loss of reflexes (lower motor neuron signs)
- Dermatomal pain and sensory loss
- Ipsilateral to rash
- Motor involvement is less common
Laboratory Tests:
- CSF analysis:
- Cell count, glucose, protein
- PCR for HSV, CMV, VZV
- West Nile virus IgM
- VDRL (for syphilis)
- Serology for HIV, Lyme disease, enteroviruses
- Normal glucose (viral causes)
- Elevated protein
- Lymphocytic predominance (except early herpes infections)
- MRI of the spine shows focal or diffuse enhancing lesions
- Inflammatory infiltration (lymphocytes, monocytes)
- Demyelination and axonal injury
Noninfectious causes include:
- Multiple sclerosis
- Vitamin B12 deficiency
- Autoimmune diseases (e.g., SLE)
- Neurosarcoidosis
- Paraneoplastic syndromes
Targeted antimicrobial therapy based on cause:
- HSV → Acyclovir
- CMV → Ganciclovir or foscarnet
- HIV → Antiretroviral therapy
- Other infections → Etiology-specific treatment
- Corticosteroids (e.g., IV methylprednisolone) are often used, though their benefit remains uncertain
- Emergency decompression if spinal cord compression (e.g., epidural abscess) is present
- Patients often require rehabilitation and neurologic follow-up
- Relapses may occur depending on etiology
- Chronic neuropathic pain
- Partial or complete paralysis
0 Comments
