Symmetrical predominantly proximal weakness in the legs

Symmetrical predominantly proximal weakness in the legs is known as a variant of lower proximal paraparesis (with total paralysis - paraplegia).

[1], [2], [3]

The causes of symmetrical predominantly proximal weakness in the legs:

1. Diseases of the motor neuron.
2. Myopathy.
3. Polyneuropathy.

Motor neuron diseases, for example, juvenile spinal muscular atrophies, especially proximal forms, less often the initially symmetrical form of amyotrophic lateral sclerosis, may result, depending on the stage of the process, on general weakness or more isolated paralysis in the proximal legs with fasciculations and marked increase in reflexes or pyramid signs. But these diseases often affect the upper limbs; The involvement of the lower extremities is usually observed against a background of more generalized suffering of motoneurons and muscles.

Myopathy, in which initially only or mainly the pelvic girdle and upper thighs are affected. This is a progressive muscular dystrophy (type II) with a pelvic belt injury, Duchenne's dystrophy (type III), dermatomyositis, etc. This localization of muscle weakness is rare in myasthenia gravis. Involvement of muscles in other diseases accompanied by myopathy is most often noted in the pelvic girdle (as in hyperthyroidism, Cushing's disease, hyperparathyroidism, and also in the picture of uremia).

Polyneuropathies sometimes occur with proximal accentuation of flaccid paralysis. Such a picture is described in Guillain-Barre syndrome, toxic polyneuropathy with intoxication with gold, vincristine, and also with polyneuropathies against the background of hyperthyroidism, giant cell arteritis, porphyria.

Diagnostic studies with proximal weakness in the legs:

EMG, muscle biopsy, CK in the blood, MRI of the spinal cord, MRI of the brain (to exclude cerebral lesion leading to lower paraparez), study of cerebrospinal fluid.

[4], [5]