HTLV-1-associated myelopathy

The most common neurological manifestation of HTLV-1 associated myelopathy is a slowly progressing chronic spastic paraparesis with bowel and bladder dysfunction and lower limb sensory disturbance ^1,4. A preceding episode of acute deterioration is reported in a minority of patients ¹. As such it is felt that there are two phases; an early acute inflammatory phase and a second chronic phase ¹. 

MRI is the modality of choice to evaluate both cranial and spinal cord manifestations. 

MRI

The most common imaging feature of HTLV-1 associated myelopathy is cord atrophy and increased signal, seen in three quarters of affected individuals ². This is most pronounced in the lateral columns, mostly involving white matter, but also involving nearby grey matter and anterior nerve roots. 

During the acute exacerbation, reported in a minority of patients, the cord is swollen and of high T2 signal with peripheral contrast enhancement ¹. 

Although the cord manifestations are the best known features of over half of affected individuals will also demonstrate high T2 signal in the cerebral white matter ². 

No accepted treatment has been shown to alter the disease outcome. Mainstay of treatment is immune modulation including steroids, plasmapheresis, danazol, pentoxifylline and interferon ^1,4. 

Differential diagnosis

The differential diagnosis depends upon the phase of the disease.

In the acute phase the main differentials include:

• transverse myelitis (including neuromyelitis optica (NMO))
• anterior spinal artery cord ischaemia

In the more common chronic phase the differential includes: 

• HIV vacuolar myelopathy: typically posterior and lateral columns ^1,4
• relapsing-remitting myelopathy (associated with anticardiolipin antibodies)
• hereditary spastic paraplegia
• multiple sclerosis
• primary lateral sclerosis
• Lyme disease
• subacute combined degeneration of the cord (usually confined to the dorsal columns)
• syphilis