Devic's syndrome (also known as Devic's disease and Neuromyelitis Optica) is a rare, chronic, inflammatory and demyelinating disease of the central nervous system (CNS) which resembles Multiple Sclerosis in several ways.

Devic's disease is characterised by attacks of acute optic neuritis (ON), usually in both eyes (bilateral).  At the same time or within a few days, weeks or occasionally months, the ON is followed by severe transverse myelopathy (TM) - acute inflammation of the spinal cord. However, in about 20% of cases, TM can precede the ON.

Optic neuritis in Devic's is often retrobulbar (not visible on back of the eye through an opthalmoscope). Recovery from attacks of Devic's disease is typically poorer than remissions from relapsing-remitting multiple sclerosis but the relapses are usually less frequent than is typical in MS.

The symptoms of Devic's disease include marked loss of vision in both eyes (optic neuritis) followed by numbness, muscle weakness, spasticity, incoordination, ataxia, urinary, bowel, sexual and autonomic dysfunction in parts of the trunk and limbs served by nerves exiting the spine below the spinal lesion.

Neurologists argue as to whether Devic's syndrome is a completely different disease to MS or whether it a variant of it. Many authors consider Devic's syndrome to be a variant of post-viral Acute Disseminated EncephaloMyelitis (ADEM) perhaps related to the varicella zoster virus. Other believe that, like MS, Devic's disease is an autoimmune condition.

The most obvious difference between the two is that Devic's typically attacks the optic nerve chiasma, optic tract, and spinal cord - usually bilaterally - whereas MS lesions can be anywhere in the CNS white matter albeit with a preference for the optic nerve, brainstem, corpus callosum and periventricular regions.
 

Principle distinguishing features between Devic's Syndrome and Multiple Sclerosis

Feature	Devic's Syndrome	Multiple Sclerosis
Clinical involvement beyond the spinal cord and optic nerves	Rarely	Usually
Attacks are bilateral	Usually	Rarely
Oligoclonal bands in Cerebrospinal Fluid (CSF)	Rarely	In over 90% of cases
White matter lesions on brain MRI	Rarely and usually resolving	Usually
Transverse Myelitis as presentation	In 20% of cases	Rarely
Swelling and signal change on MRI	Often	Less Often than Devic's
Tissue destruction and cavitation	More than MS	Less than Devic's
Protein content in CSF	Higher than MS	Lower than Devic's

Devic's disease links:
Devic's Syndrome
Clinical, CSF, and MRI findings in Devic's neuromyelitis optica
Devic's neuromyelitis optica: a study of 7 patients treated with prednisone and azathioprine
Devic's neuromyelitis optica

MS Glossary
All About Multiple Sclerosis