Neuromyelitis Optica

Original Editor - Kehinde Fatola
Top Contributors - Kehinde Fatola, Reem Ramadan, Nikhil Benhur Abburi, Kim Jackson and Leana Louw

Introduction

Neuromyelitis optica, also called NMO or Devic's disease, is a rare yet severe demyelinating autoimmune inflammatory process affecting the central nervous system. It specifically affects the myelin, which is the insulation around the nerves. NMO mainly affects the spinal cord and the optic nerves -- the nerves that carry signals from the eyes to the brain. As a result, the disease can cause paralysis and blindness. In 1894, Eugène Devic and his PhD student Fernand Gault described 16 patients who had lost vision in one or both eyes and within weeks developed severe spastic weakness of the limbs, loss of sensation and often bladder control. They recognized these symptoms were the result of inflammation of the optic nerve and spinal cord  respectively.

Epidemiology

The prevalence and incidence of Devic's disease has not been established, partly because the disease is underrecognized and often confused with multiple sclerosis. Devic's disease is more common in women than men, with women comprising over two-thirds of patients and more than 80% of those with the relapsing form of the disease. The majority of Devic's disease patients have no affected relatives, and it is generally regarded as a nonfamilial condition.

Mechanism of Injury / Pathological Process

The mechanism of injury is the inflammation and demyelination of the optic nerve (optic neuritis) and the spinal cord (myelitis).

Types

It is of two types.

• Relapsing form, which has periodic flare-ups, with some recovery in between. This is the more common kind, and women are far more likely to have this form than men.
• Monophasic form, which involves a single attack that lasts a month or 2. Men and women get this type equally.

Clinical Presentation

The main symptoms of Devic's disease are loss of vision and spinal cord function. Optic neuritis may manifest as visual impairment with decreased visual acuity, although visual field defects, or loss of color vision may occur in isolation or prior to formal loss of acuity. Spinal cord dysfunction can lead to muscle weakness, reduced sensation, or loss of bladder and bowel control. The typical patient has an acute and severe spastic weakness of the legs (paraparesis) or all four limbs (quadriparesis) with sensory signs, often accompanied by loss of bladder control. Patients may also present with endless vomiting or hiccuping and sharp pain or muscle twitches through the abdomen, back, or neck.

Diagnostic Procedures

To diagnose this condition, the examiner may;

• perform neurological examinations to examine your movement, muscle strength, coordination, sensation, memory and thinking (cognitive) functions, and vision and speech. An ophthalmologist also may be involved in the examination.
• request Magnetic Resonance Imaging (MRI) of the brain and spinal cord.
• request blood test / spinal tap (lumbar puncture) to test for antibodies which might indicate the presence of the disease.
• perform stimuli response test to learn how well your brain responds to stimuli such as sounds, sights or touch.

The tests helps to find lesions or damaged areas in the nerves, spinal cord, optic nerve, brain or brainstem.

Medical Management / Interventions

Neuromyelitis optics cannot be cured but long term remission may be possible with the right management. Interventions include treatment to reverse recent symptoms and prevent future attacks.

• Intravenous corticosteroids
• Immunosuppressants
• Plasmapheresis

Physiotherapy Management

1. Gait training
2. Wheelchair training
3. Pain reduction / management
4. Transfers
5. Reduce risk of pressure ulcers
6. Aid control to spasticity
7. Strengthening programme
8. Stretching programme

Differential Diagnosis

1. Multiple sclerosis
2. Guillain Barre Syndrome
3. Disc herniation
4. Transverse myelitis
5. Parainfectious myelitis
6. Tumour
7. Epidural or subdural hematoma
8. Epidural and/or paraspinal abscess