AMYOTROPHIC LATERAL SCLEROSIS SOCIETY OF CANADA SOCIÉTÉ CANADIENNE DE LA SCLÉROSE LATÉRALE AMYOTROPHIQUE

www.als.ca PRIMARY LATERAL SCLEROSIS (PLS) | Fact Sheet What is PLS? perform. Speech impairment may occur as Is PLS hereditary? Like ALS, primary lateral sclerosis (PLS) is a result of damage to the muscles involved PLS is not considered a genetic disorder a progressive degenerative disease of the in forming words, and swallowing and since almost all cases occur sporadically. motor neurons. It is characterized by breathing may be compromised in the later However, a very rare form of PLS with an progressive spasticity (involuntary muscle stages of the disease. early childhood or juvenile onset has been tension and spasms) and it affects the linked to a mutation in one gene. There is lower limbs, trunk, upper limbs, and bulbar The slow rate of progression allows people also a genetically mediated look-alike, muscles, usually in that order. with PLS and their families and caregivers progressive familial paraparesis (a partial more time to adapt to changes than with paralysis of the legs) which is a separate How does PLS differ from ALS? the more rapidly progressive symptoms of condition with more limited symptoms and PLS affects the upper motor neurons ALS, but the longer duration of the disease a more benign course. alone, while ALS affects the upper and places upon them a greater burden of care. lower motor neurons. The nerve cell bod- Does PLS affect one sex more than the ies of the upper motor neurons reside in What is the life expectancy of a person other? the brain, where they control the activity of with PLS? The numbers under study are too small to the lower motor neurons, which reside in In general, PLS is not considered to short- make a definitive link to gender. the spinal cord. In PLS, there is no evi- en life expectancy, although people who dence of the degeneration of spinal motor are young at the onset of the disease may What is the average age of onset of PLS? neurons that occurs in ALS. live a shorter life span. The age of onset ranges from 35-66 years with a median age of 50.5. The progress of PLS is more gradual and What causes PLS? less devastating than that of ALS. Unlike The cause of PLS is unknown. How is PLS diagnosed? ALS, PLS does not result in muscle wast- PLS is diagnosed through a process of What is the treatment for PLS? ing, and although it is disabling, it is not eliminating the possibility of other There is no treatment that will reverse or fatal. neurological disorders. Affected individuals slow the progress of PLS. Symptoms may typically have no family history of similar Some ALS specialists believe that PLS is be treated with drugs to reduce muscle disorders. There should be signs of upper on the ALS continuum and may not be a spasticity or cramps, physical therapy to motor neuron dysfunction and no signs of separate disease, but a very slow-progress- reduce joint immobility, and speech therapy involvement of other systems. ing type of ALS. ALS may begin with signs to help those whose facial muscles are of only upper or lower motor neuron affected. Early on, PLS and ALS can look very simi- involvement, so a process that begins with lar because ALS sometimes begins as an How frequently does PLS occur? upper motor neuron degeneration and that upper motor neuron disease, and the initially is considered to be PLS has the The incidence of PLS is rare, but the exact average age of onset is similar. Lower potential to be reclassified as ALS if suffi- number is uncertain. ALS affects two extremity onset and slow progression of at cient signs of both upper and lower motor individuals per 100,000 each year, and least three to five years without lower neuron involvement develop over time. tentative estimates put the annual PLS motor neuron involvement would increase incidence rate at half a per cent of that confidence in the diagnosis of PLS and number. The median duration of PLS is What are the symptoms of PLS? decrease the likelihood of a later evolution approximately 20 years, while the duration PLS usually begins with lower-extremity into ALS. stiffness and pain due to spasticity. With of ALS is two to five years, so PLS progression, which is a gradual process, prevalence is high relative to incidence People who have been diagnosed with PLS people with PLS may develop balance because people with the disease live longer. are advised to see a neurologist regularly to problems and lower back and neck pain. If tentative U.S. statistics are accurate, we be tested for the characteristic neuronal As the upper limbs become affected, activi- can extrapolate that there are approximate- degeneration of ALS. ties of daily living may become difficult to ly 50 Canadians living with PLS. By: Elaine MacNeill