Q: Could you please tell me how multiple sclerosis is diagnosed? Is it hereditary?
A: The diagnosis is indirect, by deduction from clinical and laboratory features. Typical cases can usually be diagnosed confidently on clinical grounds. The diagnosis can be suspected after a first attack. Later, a history of remissions and exacerbations and clinical evidence of central nervous system (CNS) lesions disseminated in more than one area are highly suggestive.
MRI, the most sensitive diagnostic imaging technique, may show plaques. Gadolinium-contrast enhancement can distinguish areas of active inflammation from older brain plaques. MS lesions may also be visible on contrast-enhanced CT scans.
The cerebro-spinal fluid (CSF) is abnormal in the majority of patients. IgG may be >13%, and lymphocytes and protein content may be slightly increased, but these findings are not exclusive to MS. IgG levels do correlate with disease severity.
Evoked potentials are recorded electrical responses to stimulation of a sensory system. Pattern-shift visual, brain stem auditory, and somatosensory evoked potentials may be abnormally delayed early in the disease, because demyelination slows the conduction of electrical impulses in these sensory pathways.
Age at onset is typically 20 to 40 years of age, and women are affected somewhat more often than men. This doesn’t mean that you can’t get it before 20 or after 40 years of age.
An increased family incidence and association with certain HLA allotypes suggest genetic susceptibility.
Environment may be a factor: MS is more common in temperate climates (1/2000) than in the tropics (1/10,000). It has been linked to the geographic area in which a patient’s first 15 years are spent; relocation after age 15 doesn’t alter the risk.
This is a fairly complicated answer, but MS is a complicated disorder. Visit www.msaustralia.org.au for more information.