Multiple sclerosis. Magnetic Resonance Imaging (MRI) scan of an axial section through the brain of a woman aged 47 with multiple sclerosis (MS). The two cerebral hemispheres are seen with their folded structure. At centre are two curved fluid- filled ventricles (dark). Nerve demyelination (white) in brain tissue, as occurs in MS, is seen at four places near the ends of the ventricles. This is due to the destruction of myelin sheaths around nerve fibres. Destruction of myelin in the brain and spinal cord produces such symptoms as unsteady gait, tremor, speech defects, paralysis. This patient had multiple sensory symptoms.