Multiple Sclerosis.
This is a chronic or relapsing disorder cause by episodic demyelination and formation of many small plaques throughout the CNS. Peripheral nerves are not effected. The pathogenesis involves focal disruption of the blood-brain barrier with associated immune response and myelin damage. Relapses may be triggered by otherwise innocuous infections.
Clinical: usually presents in young adult either with single focal lesion, especially unilateral optic neuritis which causes rapid deterioration in central vision, isolated numbness or with weakness of the legs. Other features are vertigo, nystagmus, double vision, pain, incontinence, cerebellar signs and Lhermitte's sign - parasthesiae in arms or legs on flexing neck. Also less commonly: facial palsy, epilepsy, aphasia, euphoria and dementia. The usual course involves initial remissions and relapses with later progressive accumulation of disability. Steady progression from outset sometimes occurs.
Examination: look carefully for signs of CNS lesion. The abdominal reflexes may be lost.
Diagnosis is based on h/o recurrent episodes of neurological disturbance implicating more than one part of the CNS, where no other explanation found. Isolated features are never diagnostic, but may become so if a careful history reveals previous neurological features such as blindness for a day or two, or investigations reveal involvement of distant parts of the CNS.
Tests: CSF: pleocytosis, protein increased, electrophoresis reveals oligoclonal bands. Visual, auditory and somatosensory evoked potentials prolonged.
Treatment: there is no cure. Dietary supplements with polyunsaturated fats may help. Treat optic neuritis with prednisolone. b - interferon appears to reduce the relapse rate. Treat spasticity. Offer incontinence aids. Help patient to live with disability. Advice is available from Disabled living foundation and MS society.
Relapse last a few months and remissions may last many years, especially if the first sign is optic neuritis, when the remission may outlive the patient.