Primary lateral sclerosis (PLS) is a motor neuron disease that occurs when the nerve cells in muscles slowly deteriorate. This leads to weakness in the voluntary muscles like the tongue, arms, and legs. Though the disease can occur regardless of age, it's most commonly seen in individuals between forty and sixty years old. There is a subtype that occurs in early childhood due to an abnormal gene passed from parent to child. Primary lateral sclerosis is less common than amyotrophic lateral sclerosis, commonly called ALS. It's often mistaken for ALS, but the symptoms progress more slowly. In the majority of cases, primary lateral sclerosis isn't fatal.
Stiffness And Weakness
It's common for primary lateral sclerosis patients to experience stiffness and weakness in their legs. The symptoms tend to progress over years, and patients may not notice them at first. Spasticity is another common PLS symptom that occurs alongside muscle weakness. This occurs when a muscle or group of muscles is contracted continuously. The contraction interferes with normal movement or walking.
Spasticity can indicate a variety of different illnesses, but it's usually caused by damage to the portion of the nervous system involved in voluntary muscle movement. Many individuals notice symptoms in their legs before the rest of their body, but there can also be weakness and stiffness in the arms. The weakness happens because the loss of nerve function causes the brain's signals to the muscles to be less strong.