Posted by: Thixia | February 20, 2008

Cognitive Dysfunction

Cognitive Dysfunction

        Studies have shown that up to 65% of MS patients have cognitive dysfunction and that cognitive dysfunction is the greatest cause for disability.  However, cognitive dysfunction is not well evaluated in the EDSS score nor in the routine office or clinic evaluation.  There is a growing awareness that cognitive dysfunction in MS is underappreciated, and the large number of poster and platform presentations concerning cognition in MS at the ECTRIMS (European Committee for Treatment and Research in Multiple Sclerosis) 2007 meeting reflects that awareness. It is important that both the practicing neurologist and academic neurologist take into consideration the cognitive function of their MS patients when evaluating the patient for DMT so that prevention of disability can be possibly achieved. Walking with a cane may not be a reason for loss of employment, but inability to follow or carry out directions or inability to formulate a plan of action may be disabling.       

A significant percentage of patients with clinically isolated syndromes (CIS) were found to have significant cognitive dysfunction when evaluated with a comprehensive neuropsychological battery.  In an evaluation of 15 patients with CIS vs 15 healthy controls, 53.3% of the CIS patients compared with 0% of the controls had cognitive dysfunction. Patients were significantly impaired on tasks evaluating attention (46.6%), long-term verbal and nonverbal memory (33.3%), visuospatial skills (26.6%), executive function (20%), and learning (20%).        

In a retrospective review of 71 MS patients with severe cognitive impairment in the first 10 years of their disease, 15 of the patients presented with cognitive impairment as their first and primary symptom.  The characteristics of these 15 patients were mean age of onset, 43 years old; 11 women, 4 men; and mean delay from symptom onset to diagnosis, 2.6 years.  Oligoclonal bands in the cerebrospinal fluid were present in all but 1 patient.  The cognitive dysfunction had a severe impact on daily living activities and remained the predominant feature of the disease for all patients even though physical disability remained mild (mild pyramidal, sensory, cerebellar, brainstem, or bladder signs in 11 of 15) or absent (in 4).         

Initial MRI pattern showed diffuse and confluent lesions in the periventricular white matter with severe cortical atrophy (n = 7, pattern A).  Others showed focal white matter lesions typical of MS with little or no atrophy (n = 8, pattern B).  Two patients’ MRIs evolved from pattern B to pattern A in 2-5 years.  Clinicians need to be aware that MS-related cognitive dysfunction can be disabling even with little or no physical disability.

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