Neuromyelitis Optica

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

Introduction

Neuromyelitis Optica (NMO) or Devic's Syndrome is a rare autoimmune disease of the Central Nervous System (CNS) that mainly affects the optic nerve (CN II), a paired nerve which conveys visual impulses to the lateral geniculate nucleus of the brain, and spinal cord. It's a demyelinating disorder thus myelin, an insulator of the CNS is the primary focus of the disease. This condition affects more prevalent in women than men.

There are two types of NMO:

• Relapsing form: This form is characterized by periodic flare-ups with some recovery and another surge later. 80% of affected patients are female.
• Monophasic form: This form is characterized by a single attack that lasts a month or two months. Men and women get this type equally.

Pathological Process

Neuromyelitis Optica is caused by a highly specific serum immunoglobulin (Ig)G autoantibody (NMO-IgG) which targets the most abundant astrocytic water channel aquaporin-4 (AQP4) causing the activation of other parts of the immune system and thus resulting in the inflammation and damage to cells as well as the demyelination of the optic nerve (optic neuritis) and the spinal cord (myelitis) . NMO-IgG/AQP4-antibodies are present in up to 80% of patients with NMO .

Clinical Presentation

Patients with NMO experience attacks that come and go. These attacks vary from mild to severe and can last from days to months ad in some cases these attacks may last and become permanent. The symptoms are broken down into three categories:

Optic neuritis occurs due to the inflammation of one or both of the optic nerves. Some of the optic neuritis symptoms include:

• Decreased visual acuity
• Visual field defects
• Color blindness
• Eye pain

Myelitis which occur due to the inflammation of the spinal cord and some of it's symptoms include:

• Muscle weakness
• Decreased sensation
• Incontinence
• Paraparesis
• Quadriparesis
• Vomiting
• Pains

Diagnostic Procedures

The following can be used to diagnose the condition;

• Neurological examinations to examine movement, muscle strength, coordination, sensation, memory and thinking (cognitive) functions, and vision and speech. An ophthalmologist also may be involved in the examination.
• Magnetic Resonance Imaging (MRI) of the brain and spinal cord.
• Blood test / spinal tap (lumbar puncture) to test for antibodies which might indicate the presence of the disease.
• Stimuli response test to learn how well the 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.

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

Medical Management / Interventions

The disease is not curable, however, proper management may ensure the patient live good quality life. Medical intervention may involve;

• Intravenous corticosteroids
• Immunosuppressants
• Plasmapheresis

Physiotherapy Management

As stated earlier, no known cure has been found for the disease yet. However, Physiotherapy management is essential for possible future remission as interventions focuses on the clinical presentations which are most times physical disabilities. Physiotherapy interventions may include;

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