Muscle weakness proximal: causes, symptoms, diagnosis, treatment

Most of the diseases discussed here lead to bilateral proximal weakness and symmetric atrophy (with the exception of proximal diabetic polyneuropathy, neuralgic amyotrophy and, in part, amyotrophic lateral sclerosis) on the arms and legs. Here, the syndromes of lesions of the humerus and lumbosacral plexus (plexopathy), which are more common on one side, are not discussed.

Proximal muscle weakness can be observed mainly in the hands, mainly in the legs or develop generalized (both in the arms and legs).

Primarily in the hands of proximal muscle weakness can sometimes be a manifestation of amyotrophic lateral syndrome; some forms of myopathies (including inflammatory ones); early stages of the Guillain-Barre syndrome; syndrome Personerson-Turner (often unilateral); polyneuropathy associated with hypoglycemia; amyloid polyneuropathy and some other forms of polyneuropathy.

Proximal muscle weakness mainly in the legs can be caused by almost the same diseases; some forms of myopathies; polyneuropathy (diabetic, some toxic and metabolic forms), polymyositis, dermatomyositis, some forms of progressive spinal amyotrophy. Some of these diseases can simultaneously or consistently cause proximal weakness in both hands and feet.

[1], [2], [3], [4], [5]

The main causes of muscular proximal weakness are:

1. Myopathy (several options).
2. Polymyositis (dermatomyositis).
3. Proximal diabetic polyneuropathy.
4. Neuralgic amyotrophy.
5. Myelitis.
6. Guillain-Barre syndrome and other polyneuropathies.
7. Amyotrophic lateral sclerosis.
8. Proximal forms of progressive spinal amyotrophy.
9. Paraneoplastic disease of the motor neuron.

Myopathy

With the gradual development of bilateral proximal muscle weakness in the proximal parts of the limbs, first of all, one should think about myopathy. The initial stage of the disease is characterized by the presence of muscle weakness, the degree of which significantly exceeds the slightly expressed atrophy of the corresponding muscles. Fasciculations are absent, deep reflexes from the limbs are preserved or slightly reduced. In the sensitive sphere, there is no change. During physical exertion, the patient may experience pain, which indicates a fairly common involvement of the corresponding muscle groups in the pathological process and indicates a disruption in the functioning of the normal mechanism of alternately turning on a working and resting portion of muscle (muscle).

The main clinical phenomenon can be clearly recorded by electromyographic examination: a characteristic feature is the early inclusion of a large number of muscle fibers, which is reflected in the form of a characteristic "dense" pattern of the action potential of the motor unit. Since in myopathy almost all the muscle fibers of the affected muscle are involved in the pathological process, the amplitude of the action potential of the motor units is significantly reduced.

Myopathy is not a diagnosis; this term only indicates the muscular level of the lesion. Not all myopathies are degenerative in nature. Clarification of the nature of myopathy allows the development of appropriate treatment tactics. Some myopathies are a manifestation of potentially curable diseases, for example - metabolic disorders or autoimmune diseases.

Quite valuable information about the possible cause of myopathy can be given by laboratory studies. The most informative is the study of muscle biopsies. In addition to the study of myobiotic by light or electron microscopy, it is absolutely necessary to use modern enzymatic histochemical and immunochemical studies.

The first of the "degenerative" myopathies should be considered muscular dystrophy. The most frequent clinical variant, manifested in the form of proximal muscle weakness, is the "limb-belt" form of muscular dystrophy. The first signs of the disease are found, as a rule, in the 2nd decade of life; the disease is characterized by a relatively benign course. It manifests itself with muscle weakness, and then with atrophy of the muscles of the pelvic girdle and the proximal parts of the legs; less often, the muscles of the shoulder girdle also suffer. The patient begins to use the characteristic "myopathic" techniques in the process of self-service. A specific habit develops with a "duck" gait, hyperlordosis, "pterygoid shoulder blades" and characteristic dysbasia. Another form of myodystrophy, Duchenne's pseudohypertrophic myostrophy, is quite easy to diagnose , which, on the contrary, is characterized by rapid progression and debut at the age of 5 to 6 years exclusively in boys. Becker 's muscular dystrophy by the nature of muscle involvement is similar to Duchenne's myodystrophy, but differs in a benign course. The proximal parts of the hands are involved in the pathological process of face-scapular-brachial muscular dystrophy.

At the head of the list of non-degenerative myopathy (which, of course, is not complete here and is represented only by the basic forms), chronic thyrotoxic myopathy (and other endocrine myopathies) should be put . In general, any endocrine pathology can lead to the development of chronic myopathy. A feature of myopathy in systemic lupus erythematosus is the soreness of muscle contractions. Paraneoplastic myopathy often precedes the appearance of symptoms of malignant neoplasm. It is necessary to remember the possibility of development of iatrogenic steroid myopathy with proximal weakness (in the legs). The diagnosis of "menopausal myopathy" should be made only after excluding all other causes of myopathy. Myopathy in disorders of glycogen metabolism develops mainly in childhood and is characterized by pain in the muscles during exercise. Generally speaking, the combination of proximal muscle weakness with pain during exercise should always address the physician to the possible metabolic disorders that underlie muscle damage and should be the basis for conducting laboratory tests and biopsy of muscle tissue.

Poliomyositis

In most cases, the term "polymyositis" refers to an autoimmune disease that occurs with the predominant involvement of the muscles of the proximal parts of the extremities and the muscles of the pelvic girdle (and neck muscles). Age and nature of the onset of the disease are very variable. More characteristic is the gradual onset and course with relapses and periodic increase in symptoms, early occurrence of swallowing disorders, soreness of the affected muscles and laboratory data confirming the presence of an acute inflammatory process. Tendon reflexes are preserved. As a rule, the level of creatine phosphokinase of blood is increased, which indicates a rapid destruction of muscle fibers. Myoglobinuria is possible, and obturation of renal tubules with myoglobin can lead to the development of acute renal failure (as in the syndrome of "compression", "crash syndrome"). In the formulation of the diagnosis, the presence of erythema on the face and chest ("dermatomyositis") helps. In men, polymyositis is often paraneoplastic.

With EMG, the "myopathic changes" described above and the spontaneous activity indicating damage to the terminal branches of the nerves are revealed. At the acute stage of the disease, a biopsy almost always makes it possible to confirm the diagnosis if a perivascular infiltration of lymphocytes and plasma cells is detected during the study of the biopsy. However, in the chronic stage, it is not easy to differentiate polymyositis from muscular dystrophy.

Separate from the main group of polymyositis are inflammatory processes in the muscles caused by specific microorganisms. An example may be a myositis of a viral nature, characterized by an acute onset with severe pain and very high rates of ESR. Severe pain manifestations are also characteristic of limited myositis in sarcoidosis and trichinosis. This is also characteristic of rheumatic polymyalgia (polymyalgia rheumatica) - a muscle disease that occurs in mature and old age and proceeds with severe pain syndrome. True muscle weakness, as a rule, is absent or expressed minimally - movements are hampered by intense pain, especially in the muscles of the shoulder and pelvic girdle. EMG and biopsy do not reveal signs of damage to muscle fibers. ESR is significantly increased (50-100 mm per hour), laboratory indicators indicate subacute inflammatory process, CK is more often normal. Slightly expressed anemia is possible. A rapid effect of corticosteroids is characteristic. In some patients arteritis of cranial localization (temporal arteritis) arises later.

Proximal diabetic polyneuropathy (diabetic amyotrophy)

Proximal muscle weakness may be a manifestation of the pathology of the peripheral nervous system, most often diabetic neuropathy. Such a clinical variant of diabetic polyneuropathy involving proximal muscle groups is much less known to physicians than the well-known form of diabetic polyneuropathy, in which there is a bilateral symmetrical distal sensorimotor defect. Some of the elderly patients with diabetes develop proximal limb weakness, usually asymmetric, often with pain, but the most obvious motor defect is weakness and proximal atrophy. Difficulty is the ascent and descent from the stairs, rising from the sitting position, transition to a sitting position from the supine position. Achilles reflexes can remain preserved, but knee reflexes, as a rule, are absent; the quadriceps muscle of the thigh is painful on palpation, paretic and hypotrophic. Weakness in m. Ileopsoas. (A similar picture of asymmetric proximal weakness and atrophy is given by diseases such as carcinomatous or lymphomatous radiculopathy).

For the development of proximal diabetic polyneuropathy (as well as for the development of all other forms of diabetic neuropathy) there is not necessarily the presence of severe metabolic disturbances: sometimes they can be detected for the first time when conducting a glucose tolerant test (latent diabetes).

Neuralgic amyotrophy (shoulder girdle, pelvic girdle)

Asymmetric proximal diabetic polyneuropathy in the lower limbs should be distinguished from a one-sided lesion of the lumbar plexus - a disease similar to the well-known neuralgic amyotrophy of the muscles of the shoulder girdle. Clinical observations of the last 10 years have shown that a similar pathological process can affect the lumbar plexus. The clinical picture is represented by the symptoms of acute unilateral defeat of the femoral nerve with the development of paralysis of the innervated muscles. A thorough examination, including EMG and a study of nerve conduction velocity, can also reveal the light involvement of neighboring nerves, for example, the occlusal nerve, which manifests itself in the weakness of the leading hamstrings. The disease has a benign character, recovery comes in a few weeks or months.

It is extremely important to ensure that the patient does not have two other possible diseases requiring a specific diagnostic approach and treatment. The first is damage to the third or fourth lumbar spinal cord: in this case, sweating is not impaired on the anterior surface of the upper thigh, since the vegetative fibers leave the spinal cord in the rootlets not lower than the second lumbar spine.

Sweating is disturbed in malignant tumors in the pelvis, affecting the lumbar plexus, through which the vegetative fibers pass. Another cause of compression of the lumbar plexus, which should be borne in mind, is spontaneous retroperitoneal hematoma in patients receiving anticoagulants. In this situation, the patient has pain due to initial compression of the femoral nerve hematoma; to relieve pain, the patient takes analgesics, analgesics increase the effect of anticoagulants, which leads to a further increase in the volume of hematoma and pressure on the femoral nerve, followed by the development of paralysis.

Myelitis

Cases of myelitis with the development of proximal paresis have become rare since poliomyelitis practically disappeared from clinical practice. Other viral infections caused, for example, by the Coxsackie type A virus, can mimic poliomyelitis neurological syndrome, leading to the development of an asymmetric proximal paresis with no reflexes with a safe sensitivity. In the cerebrospinal fluid, increased cytosis, a slight increase in protein level and a relatively low level of lactate are detected.

Guillain-Barre syndrome and other polyneuropathies

The myelitis described above should be differentiated from Guillain-Barre syndrome, which in the early days of the disease is a very difficult task. Neurological manifestations are very similar - even lesion of the facial nerve can be observed in both diseases. Rates of conduction along the nerves in the first days can remain normal, the same applies to the level of protein in the cerebrospinal fluid. In pleasing myelitis, pleocytosis is indicated, although it is also found in Guillain-Barre syndrome, in particular, in the Guillain-Barre syndrome of viral nature (eg, caused by the Epstein-Barr virus). Involvement of the autonomic nervous system is an important diagnostic criterion in favor of Guillain-Barre syndrome, if it has been proved that the heart rate is inactive for stimulation of the vagus nerve or other symptoms of peripheral vegetative insufficiency are revealed. Dysfunction of the bladder is observed in both pathological conditions, the same applies to paralysis of the respiratory muscles. Sometimes only monitoring the course of the disease with a re-evaluation of the neurological status and the speed of the nerves allows the diagnosis to be correctly diagnosed. For some other forms of polyneuropathy, a predominantly proximal accentuation of the process (polyneuropathy in the treatment of vincristine, in contact with the skin with mercury, polyneuropathy in the giant cell arteritis) is also characteristic. HVDP sometimes manifests a similar picture.

Amyotrophic lateral sclerosis

The debut of amyotrophic lateral sclerosis from the proximal parts of the hand is not a frequent phenomenon, but quite possible. Asymmetric amyotrophy (at the beginning of the disease) with hyperreflexia (and fasciculations) is a characteristic clinical marker of amyotrophic lateral sclerosis. EMG reveals the pre-hype interest even in clinically preserved muscles. The disease is steadily progressing.

[6], [7], [8], [9]

Progressive spinal amyotrophies

Some forms of progressive spinal amyotrophy (Verdnig-Hoffmann amyotrophy, Kugelberg-Welander amyotrophy) refer to proximal spinal amitorphs of a hereditary nature. Fasciculations are not always available. The sphincter functions are preserved. For the diagnosis, the most important is EMG. Conducting systems of the spinal cord, as a rule, are not involved.

Paraneoplastic syndrome

Paraneoplastic motor neuron disease (spinal cord injury) can sometimes mimic progressive spinal amyotrophy.

How is proximal muscle weakness recognized?

General and biochemical blood test; Analysis of urine; EMG; muscle biopsy; examination of the level of CK in the blood; determination of the rate of excitation along the nerve; investigation of cerebrospinal fluid; consultation of the therapist; if necessary - oncological search and other (according to testimony) studies.