The distinguishing features of acute disseminated encephalomyelitis (DEM) and multiple sclerosis (MS) are reviewed by researchers at Harvard Medical School, Boston, MA, and University of Zagreb, Croatia. Acute and recurrent DEM affect children more than adults. Symptoms of DEM such as fever, altered consciousness, aphasia, and meningism are rare in MS. CSF oligoclonal bands are also rare. Genetic factors are often involved in MS but they are absent in ADEM. MRI is the best method of distinguishing the two distinct diseases. In DEM or ADEM, the lesions are larger than the plaques found in MS, they enhance with gadolinium, and often involve the thalamus and basal ganglia. MRI McDonald criteria for the diagnosis of MS require one enhancing or nine T-2 lesions: one infratentorial and one juxtacortical; and three or more periventricular lesions. The demyelinating lesions are disseminated in both diseases but differ in form and size; in MS the plaques are small and have characteristic sharply defined borders, whereas in ADEM they are large and ill-defined, inflammatory and perivenous.

Both brain and spinal cord MRI should be obtained in cases of clinically isolated syndrome (CIS) suggesting demyelination. Spinal cord lesions in DEM are elongated, whereas in MS they are less than two or three vertebral segments in length. In ADEM, cerebral MRI lesions may be massive, sometimes mistaken for tumors, Schilder's or Balo's disease, or strokes. Devic's syndrome or neuromyelitis optica, called ‘Oriental form of MS’ in Japan, has been classified as a form of MS in the past. Recent reports suggest that Devic's syndrome is different from MS and more closely resembles DEM. Treatment and prognostic considerations are important reasons to differentiate between a CIS of MS and acute DEM, and between relapsing-remitting MS and recurrent DEM. Lifelong immunomodulatory treatment is initiated immediately after an MS CIS, whereas IV methylprednisolone, IV immunoglobulin G, or plasma exchange are accepted treatments for ADEM. [1]

COMMENT. The differentiation of ADEM and MS is made on clinical history, neurologic and MRI findings, and CSF analysis. Given the variety and remitting nature of clinical symptoms of demyelinating disease, a neurologist with expertise in neuroradiology may be best qualified to correctly diagnose the disorder. The above review regards the two diseases as distinct entities and not parts of a spectrum, as sometimes proposed.

The spectrum of neuromyelitis optica, (NMO). Researchers from the Mayo Clinic, Scottsdale, AZ, and Rochester, MN, review the role of the serum autoantibody marker (NMO-IgG) in the pathogenesis of NMO and in the definition of an extended spectrum of NMO-related disorders, distinct from MS [2]. The potential pathogenicity of NMO-IgG, the role of aquaporin 4 as the inducer and target of the autoimmune attack, with resulting inflammatory demyelination and necrosis, and treatment are discussed. The revised Wingerchuk diagnostic criteria for NMO require 2 of the following: 1) Brain MRI is not diagnostic of MS; 2) spinal cord lesion must be 3 or more segments in length; and 3) patient is NMO-IgG antibody seropositive.

NMO in a mother and daughter is reported from University of Michigan, Ann Arbor [3]. The ages of onset were 62 and 29 years, respectively. Few familial cases of NMO are described.