What Is Primary Lateral Sclerosis?

Primary lateral sclerosis (PLS) is a very rare motor neuron disease. The etiology and pathogenesis are still unclear. The clinical manifestations are progressive motor neuron dysfunction. It usually develops after middle age, has an insidious onset, progresses slowly, and can survive for a long time. PLS is a degeneration of the upper motor neuron characterized by spinal cord and bulbar paralysis, and the pathological manifestation is a significant demyelination of the corticospinal tract.

Primary lateral sclerosis (PLS) is a very rare motor neuron disease. The etiology and pathogenesis are still unclear. The clinical manifestations are progressive motor neuron dysfunction. It usually develops after middle age, has an insidious onset, progresses slowly, and can survive for a long time. PLS is a degeneration of the upper motor neuron characterized by spinal cord and bulbar paralysis, and the pathological manifestation is a significant demyelination of the corticospinal tract.

Chinese name

Primary lateral sclerosis

Foreign name

primary lateral sclerosis, PLS

Causes of common lateral sclerosis and common diseases

PLS lesions are limited to the upper motor neurons. In the early stages of the disease, the cortical neurons in the motor area are intact, and the spinal cord cones show significant demyelinating changes. As the disease progresses, the brain stem, inner capsule, and central anterior gyrus Cells also degenerate, this is called retrograde death. Some scholars have reported a case of amyotrophic lateral sclerosis (ALS) with ophthalmoplegia. In the autopsy, it was found that the central anterior gyrus cortex cells were significantly missing, the glial cells proliferated, and the bilateral cortical spinal cord in the brain stem and spinal cord. There are also axonal deletions and glial cell hyperplasia changes, while cortical cell deletions are often confined to the Betz cell layer, suggesting that a pronounced symmetrical atrophy of the central anterior gyrus is a special feature of PLS.

The first symptom is usually symmetrical stiffness and weakness of both lower limbs with gait of walking scissors, which gradually affects both upper limbs. Extremity tension increased spastically, tendon reflexes were hyperactive, and pathological reflexes were positive. Mostly there is no muscle atrophy and fasciculation, and there is no obstacle to sphincter function. When bilateral cortical brainstem bundles are damaged, the appearance of pseudobulbar paralysis can occur. The course of the disease is slow and can survive for a long time.

Differential diagnosis of primary lateral sclerosis

The clinical manifestations of PLS are diverse. Symptoms usually begin in the age of 50 to 60. The most common clinical symptoms are spinal spastic paralysis, including limb rigidity, hyperreflexia, and mild weakness. PLS is very rare, and the symptoms are non-specific. If the clinician does not carefully check the medical history and perform a detailed neurological examination, it may easily lead to misdiagnosis.

Some scholars have proposed the diagnostic criteria for PLS: adult occult onset spastic paralysis, which usually starts in the lower limbs, has no family history, and progresses slowly for at least 3 years, eventually leading to severe spastic spinal palsy, pseudobulbar palsy, and MRI. The central anterior gyrus atrophy. As more cases of PLS are reported, some scholars believe that primary lateral sclerosis can be transformed into ALS.

The main characteristics of PLS are: (1) the onset is hidden and slowly progresses; (2) the age of onset is 15-50 years old or older; (3) the clinical manifestations of spastic paralysis of the limbs with bilateral cortical spinal cord injury, The lower limbs are heavy, and if the cortical medullary tract is involved, there will be signs of pseudobulbar palsy; (4) no localized muscle weakness, muscle atrophy, and myofibrillation, no sensory disturbance; (5) EMG without denervation signs; MRI axial T ₂ WI showed abnormally high signal in the brainstem, bilateral inner capsule area and bilateral motor area cortex; (7) exclude other diseases, such as multiple sclerosis.

Primary lateral sclerosis

Can be used for EMG, nerve conduction velocity, EEG, CT and MRI examinations. Electromyography can show a decrease or normal motor nerve conduction velocity, while sensory nerve conduction velocity is normal.

Principles of treatment of primary lateral sclerosis

The treatment of PLS is still mainly supportive today, including rehabilitation exercises, the use of drugs to relieve muscle tone, and pseudobulbar paralysis. PLS has a better prognosis than ALS, with an average survival time of more than 10 years. In short, for patients with clinically progressive upper motor neuron damage, PLS should be highly suspected after detailed medical history inquiry, neurological examination, laboratory and imaging examinations to rule out other diseases, early diagnosis, and early treatment may be possible. Will delay the development of the condition.