Update on Multiple Sclerosis Diagnostic Criteria
New criteria are aimed at simplifying magnetic resonance imaging requirements in assessment of clinically isolated syndromes.
This update of the 2005 McDonald criteria for diagnosing multiple sclerosis (MS) is an effort to simplify and improve on the previous criteria (Ann Neurol 2005; 58:840) in light of recent investigations. The authoring panel stresses that these criteria should be used only for assessing a classic demyelinating event. The new criteria are as follows:
* Magnetic resonance imaging (MRI) can now demonstrate dissemination in space (DIS) by as few as two lesions, with ≥1 T2 lesions in ≥2 typical MS locations (juxtacortical, periventricular, infratentorial, spinal cord) — a simpler algorithm than was previously used.
* Dissemination in time (DIT) can now be satisfied by one of the following two criteria:
— A new T2 lesion on a second MRI scan obtained at least 30 days after a first scan (simplified from the prior need to reestablish baseline with a new MRI scan 30 days after the clinical event, which would amount to three scans to document a new lesion).
— Co-occurrence of ≥2 asymptomatic T2 lesions on the very first MRI scan, at least one of which enhances with gadolinium (Gd) and at least one of which does not enhance.
* A diagnosis of primary progressive MS (PPMS) requires 1 year of disease progression plus two of the following: a positive brain MRI, ≥2 T2 spinal cord lesions, oligoclonal bands and/or elevated immunoglobulin G index in the cerebrospinal fluid.
* Neuromyelitis optica should be considered with transverse myelitis extending beyond three spinal segments, bilateral or severe optic neuritis, or intractable hiccups or nausea/vomiting accompanied by a medullary lesion on MRI.
Comment: This updated set of evidence-based criteria will simplify entry of patients into MS clinical studies. Several caveats about the underlying evidence must be stressed. These criteria were derived in patients who presented with very typical demyelinating syndromes (e.g., optic nerve, brainstem, and spinal cord localizations), had a mean age of 31 to 32, were Western European, and were scanned with MRI magnetic field strengths ≤1.5 T. The dating of lesions on a single scan with Gd for DIT is an interesting development, as Gd sensitivity can be influenced by several variables (e.g., dose, timing, agent, field strength, T1 sequence).
In clinical practice, these criteria are not appropriate for patients with nonspecific neurological symptoms and signs and an abnormal MRI scan. Caution is also advisable for patients older than 50 or younger than 20. As always, other diseases must be excluded; careful history and exam are needed to identify "red flags" against MS diagnosis. In clinical practice, for young adults who present with very clear demyelinating syndromes, these criteria will aid initial and follow-up assessments for MS risk stratification, diagnosis, and treatment discussions.
— Robert T. Naismith, MD
Published in Journal Watch Neurology January 25, 2011
Polman CH et al. Diagnostic criteria for multiple sclerosis: 2010 revisions to the "McDonald criteria." Ann Neurol 2011 Jan 11; [e-pub ahead of print]. (http://dx.doi.org/10.1002/ana.22366)