Answer of August 2010

Clinical History:

A 12-year-old girl presented with blurring of vision for 3 days without associated limb weakness. MRI of brain was obtained. One month later, she developed bilateral lower limb weakness. MRI of spine was obtained. CSF study was unremarkable.

Diagnosis:

Neuromyelitis optica

Discussion:

MRI of brain showed T1hypo- & T2 hyperintense area over right temporal & parietal region of the brain and bilateral swollen optic nerves.

MRI of spine showed swollen cervical cord with T2 hyperintensity extending from C1/2 level down to C5 level.  Focal patchy contrast enhancement was noted.

Neuromyelitis optica (NMO), also known as Devic¡¦s disease, is a relapsing inflammatory demyelinating disease of the central nervous system (CNS) of unknown origin.  It is characterized by optic neuritis and acute myelitis.  Other areas of the CNS are usually not affected.  MRI typically demonstrates a longitudinal T2 high signal lesion extending over a long segment of spinal cord.

A proposed diagnostic criteria for diagnosis by Mayo Clinic for definite NMO would include optic neuritis, acute myelitis and at least two of three supportive criteria: 1. Contiguous spinal cord MRI lesion extending over >= 3 vertebral segments, 2. Brain MRI not meeting diagnostic criteria for multiple sclerosis (MS), 3. NMO-IgG seropositive status.

In early course of of Devic¡¦s disease, it may be difficult to distinguish it from multiple sclerosis (MS).  According to Mayo Clinic, there are several important differences between Devic¡¦s disease and multiple sclerosis:

Clinically, Devic's disease affects only the optic nerves and spinal cord, whereas MS affects the brain as well.  Attacks of Devic's disease tend to be more frequent and severe than attacks of MS, though this is not always the case.  An MRI of the brain is typically normal in Devics disease, although this is not always the case; in MS the MRI of the brain typically shows many areas of inflammation.  An MRI of the spinal cord shows continuous extensive inflammation of the spinal cord whereas spinal cord inflammation in MS typically occurs in much smaller patches.  Spinal fluid in Devic's disease usually lacks the typical elevation of antibodies detected in patients with MS, although occasional patients may show this abnormal pattern of antibodies.  The autoantibody NMO-IgG is specific for Devic's disease but is undetected in 30 percent of patient.