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SECONDARY
CLINICAL PROGRESSSION IS RARE IN NEUROMYLELITIS OPTICA
SAN DIEGO—A secondary progressive disease course is uncommon in neuromyelitis optica, unlike the situation in relapsing-remitting multiple sclerosis (MS), where patients accrue most of their neurologic impairment during the secondary progressive phase of the disease," Dean Wingerchuk, MD, said. "We previously demonstrated that the median time from neuromyelitis optica onset to established serious disability—blindness in at least one eye or requirement for gait assistance—is approximately five years. However, we have observed that a secondary progressive disease course is uncommon in neuromyelitis optica."
Dr. Wingerchuk, Associate Professor of Neurology at the Mayo Clinic, Scottsdale, Arizona, and colleagues studied 96 neuromyelitis optica patients. They defined secondary progression as continuous deterioration without remission over more than 12 months, preceded by one or more attacks, and with deterioration in visual and/or sensory function. "To include an individual patient we required that they have at least two evaluable limbs and at least one evaluable eye," Dr. Wingerchuk said in his presentation at the 58th Annual Meeting of the American Academy of Neurology, meaning that there was sufficient remaining function that gradual progression could be detected.
LOW-FREQUENCY FINDINGS
"We used time from neuromyelitis optica onset to either secondary progression onset or last follow-up to compare the actual neuromyelitis optica secondary progression frequency to an expected frequency estimated from published population-based MS natural history data from London, Ontario," Dr. Wingerchuk said. Median age at onset was 38.3, follow-up duration was 3.6 years, and median relapse number was four.
"We expected to find approximately 24 secondary progression patients in the neuromyelitis optica cohort if it occurred at the same rate as in MS, but found only two (2.1%). In both cases, the secondary progressive course manifested as a progressive myelopathy; latency from neuromyelitis optica onset to onset of secondary progression was three years after a single attack in one patient and 13 years after a series of 10 attacks in the other."
The investigators concluded that neuromyelitis optica–related disability is almost exclusively attack-related. "This underscores the importance of early diagnosis and immunotherapy. Patients who present with a single event of longitudinally extensive transverse myelitis and are seropositive have a relapse risk over the next year of greater than 50%, so there is a rationale for immunotherapy even after a single attack," Dr. Wingerchuk said.
NR
—Janis Kelly
Suggested Reading
Wingerchuk D. Neuromyelitis optica. Int MS J. 2006;13:42-50.
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