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Primary lateral sclerosis (PLS) is an idiopathic non-familial neurodegenerative disorder of upper motor neurons, presenting as a slowly progressive pyramidal tract syndrome. The annual incidence and the prevalence of PLS are estimated to 1 in 1,000,000 and 10-20 in 1,000,000, respectively. Disease onset is usually between 40 and 60 years with spasticity in the legs. Onset in the pseudobulbar region with speech and swallowing disturbance is also possible. Ultimately, a tetrapyramidal syndrome develops, sometimes with marked pseudobulbar features (forced laughing and crying). Pringle criteria for PLS consist of adult onset of symptoms, a negative family history, normal findings of blood, urine and cerebrospinal fluid (CSF) tests, no abnormalities on EMG, and on brain and spinal cord MRI. PLS is considered to be a benign variant of Amyotrophic lateral sclerosis (ALS). The etiology is not known. Treatment of PLS is symptomatic and can involve prescription of antispasticity medication and rehabilitation. Life expectancy is normal. |