Polyneuropathy - Symptoms

The clinical picture of polyneuropathy usually combines signs of damage to motor, sensory and vegetative fibers. Depending on the degree of involvement of fibers of different types, motor, sensory or vegetative symptoms may predominate in the neurological status.

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

Symptoms

Damage to motor fibers leads to the development of flaccid paresis, most neuropathies are characterized by damage to the upper and lower extremities with a distal distribution of muscle weakness, with long-term existing damage to the axon, muscle atrophy develops. Axonal and hereditary polyneuropathies are characterized by a distal distribution of muscle weakness, more often the lower extremities are affected, weakness is more pronounced in the extensor muscles than in the flexor muscles. With severe weakness of the peroneal muscle group, steppage ("cock gait") develops. Acquired demyelinating polyneuropathies can manifest as proximal muscle weakness. In severe cases, damage to the cranial nerves and respiratory muscles can be noted, which is most often observed in Guillain-Barré syndrome.

Polyneuropathies are characterized by relative symmetry of symptoms. Asymmetric muscle weakness and atrophy are observed in multiple mononeuropathies: multifocal motor neuropathy, multifocal sensorimotor neuropathy of Sumner-Lewis.

Tendon and periosteal reflexes in polyneuropathy are usually reduced or disappear, primarily reflexes from the Achilles tendon are reduced, with further development of the process - knee and carporadial, tendon reflexes from the biceps and triceps of the shoulder may be preserved for a long time. In multiple mononeuropathies, tendon reflexes may remain preserved and even brisk for a long time.

Sensory disturbances in polyneuropathy are also most often relatively symmetrical, initially occurring in the distal sections (like "socks" and "gloves") and spreading proximally. At the onset of polyneuropathy, positive sensory symptoms (paresthesia, dysesthesia, hyperesthesia) are often detected, but as the process develops further, symptoms of irritation are replaced by symptoms of loss (hypesthesia). Damage to thick myelinated fibers leads to disturbances in deep muscle and vibration sensitivity, damage to thin myelinated fibers leads to disturbances in pain and temperature sensitivity.

A characteristic symptom of many polyneuropathies is pain syndrome, which is most typical for diabetic, alcoholic, toxic polyneuropathies, porphyric polyneuropathy, etc.

Impairment of vegetative functions is most clearly manifested in axonal polyneuropathies, since vegetative fibers are unmyelinated. Symptoms of loss are most often observed: damage to sympathetic fibers that go with the peripheral nerves is manifested by dry skin, impaired regulation of vascular tone; damage to visceral vegetative fibers leads to dysautonomia (orthostatic hypotension, tachycardia, decreased heart rate variability, gastrointestinal dysfunction, decreased erectile function). Signs of dysautonomia are most pronounced in hereditary vegetative-sensory polyneuropathies, diabetic polyneuropathy. Impairment of vegetative regulation of the heart can cause sudden death. Vegetative manifestations in polyneuropathies can also manifest as symptoms of irritation (hyperhidrosis, vascular tone disturbance), which is often noted in vibration disease, porphyric polyneuropathy.

Clinical manifestations of neuropathy consist of three types of symptoms: sensory, motor and vegetative. Vegetative disorders in polyneuropathies are more common. Forms of neuropathic syndromes have been identified in which a syndrome of progressive vegetative insufficiency is formed. In this case, the symptoms of vegetative insufficiency can obscure the manifestations of the underlying disease and are caused primarily by visceral polyneuropathy. A similar example is diabetic polyneuropathy, accompanied by severe orthostatic hypotension, impotence, impaired sweating and changes in pupillary response. Similar disorders are found in patients with amyloid neuropathy.

Peripheral autonomic disorders manifest themselves as pain, vascular and persistent trophic phenomena. The most striking and intense autonomic disorders in the extremities are observed in hereditary sensory neuropathy. This category includes a number of diseases characterized by a pronounced loss of sensitivity or autonomic dysfunction, or a combination of these disorders. An essential feature of these forms is the presence of pronounced trophic disorders, especially in the lower extremities. There are indications of the presence of hereditary perforating ulcers of the foot in some cases. The disease, as a rule, begins with the loss of pain and temperature sensitivity in the distal parts of the lower extremities, then similar changes in the upper extremities join. Other types of sensitivity are also affected, mild motor disorders in the distal parts of the extremities may appear. A feature of the disease is excruciating spontaneous pain, mainly in the legs. Frequent symptoms include neuropathic degeneration of the joints and persistent ulceration of the feet. The disease manifests itself early, and in the recessively inherited variant, symptoms are observed from birth.

In a rare form, congenital sensory neuropathy with anhidrosis, along with delayed motor development and episodes of unexplained fever, loss of pain and temperature sensitivity, bone fractures, skin ulcers, and occasionally self-medication are observed.

The picture of skin changes is unique and inimitable, and they are often the first symptom of fairly common forms of polyneuropathies that accompany systemic connective tissue diseases. Peripheral nerve damage may be the only clinical manifestation of a systemic disease for a long time. Most often, polyneuropathic syndromes develop with systemic lupus erythematosus, rheumatoid arthritis, systemic scleroderma, vasculitis, mixed connective tissue disease, cryoglobulinemia, Sjogren's syndrome, etc.

In some collagenoses (for example, in nodular periarteritis), the probability of damage to the peripheral nervous system is higher. Peripheral autonomic disorders are associated with the development of neuropathy, which manifests itself as distal paresthesia with decreased sensitivity. In severe cases, the clinical picture is complicated by manifestations of cutaneous vasculitis or concomitant joint deformities characteristic of rheumatoid arthritis, the development of trophic skin lesions - swelling of the fingers and hands, sometimes with thinning of the skin and disappearance of skin folds, hyperpigmentation with areas of depigmentation and telangiectasia, as is often observed in systemic scleroderma.

Forms

I. Classification of polyneuropathy (and neuropathy in general) according to predominant clinical signs:

1. motor neuropathy;
2. sensory neuropathy;
3. autonomic neuropathy;
4. mixed neuropathy.

II. Classification of neuropathy by the nature of the distribution of damage:

1. distal (usually symmetrical) involvement of the limbs;
2. multiple mononeuropathy (usually asymmetrical proximal lesion); polyneuropathy with predominant involvement of the upper extremities and polyneuropathy with predominant involvement of the lower extremities are also distinguished (the latter variant is significantly more common). A rare variant is polyneuropathy with predominant involvement of the cranial nerves.

III. Classification of polyneuropathy by the nature of the course:

1. acute (symptoms develop over several days);
2. subacute (over several weeks);
3. chronic (over several months or years).

The chronic form is divided into chronic progressive and chronic relapsing forms. Acute onset is typical for inflammatory, immune, toxic or vascular etiology. Polyneuropathy that develops slowly (years) indicates a hereditary or, less commonly, metabolic origin. There are forms that persist throughout life.

Most toxic, nutritional and systemic diseases develop subacutely over weeks or months.

Hereditary polyneuropathies

NMSN types I (demyelinating) and II (axonal), known as Charcot-Marie-Tooth disease, have a generally similar clinical picture. The disease most often debuts in the first or second decade of life. At the onset of the disease, symmetrical weakness of the peroneal muscle group, steppage develops, then atrophy of the muscles of the feet and shins gradually appears ("stork legs"). Weakness and atrophy of the distal muscles of the lower extremities lead to characteristic changes in the feet (formation of a "hollow" or "horse" foot, a change in the feet according to the Friedreich type). The gastrocnemius muscles remain intact for a long time. Weakness in the arm muscles joins in 10-15 years after the onset of the disease. Sensory disturbances are most often represented by moderate hypoesthesia of the "high socks" and "gloves" type. Paresthesia and autonomic disorders are not characteristic of hereditary polyneuropathies. Pain syndrome is rarely expressed and is most often associated with foot deformation and orthopedic disorders. Proximal muscles remain practically intact, due to which patients retain the ability to move independently for the rest of their lives. In 100% of cases, Achilles reflexes disappear, later the knee reflexes fade, then the carporadial reflexes.

The clinical picture of Roussy-Lévy syndrome, a phenotypic variant of type IA NMS, includes areflexia, ataxia, and tremor. Roussy-Lévy syndrome is characterized by pronounced demyelination (the nerve conduction velocity in the legs does not exceed 5-16 m/s) with relatively preserved axon function (according to needle EMG, the denervation process is weakly expressed, atrophy affects only the muscles of the feet, while the muscles of the lower legs remain relatively intact, so steppage is not characteristic of this form). In 50% of cases, foot deformities of the Friedreich type (or high arches of the feet), weakness of the distal muscles of the feet, hypoesthesia in the distal parts of the lower extremities, impaired joint-muscle sense, and absence of tendon reflexes are detected. In general, the course of Russy-Levy syndrome is more favorable than that of type IA NMS, which occurs as neural amyotrophy.

Hereditary neuropathy with a tendency to palsy from compression is characterized by an autosomal dominant type of inheritance and manifests itself in recurrent multiple mononeuropathies. Patients are usually observed for frequent tunnel neuropathies, while it is noteworthy that local demyelination is caused by minor compression. With further development of the process, mosaic symptoms arise, associated with residual effects after suffered tunnel syndromes.

[ 6 ], [ 7 ], [ 8 ], [ 9 ], [ 10 ], [ 11 ]

Polyneuropathy with porphyria

Acute intermittent porphyria is a hereditary autosomal dominant disease characterized by periodic attacks of abdominal pain, which are combined with the acute development of polyneuropathy and various disorders of the central nervous system. An attack is usually provoked by alcohol or drug intake, anesthesia, stress. Acute onset of abdominal pain, diarrhea with the development of tetraparesis after 2-4 days are characteristic. In severe cases, damage to the bulbar and respiratory muscles occurs. In most cases, the attack passes without a trace after 1-2 months. Porphyric polyneuropathy is characterized by a non-classical distribution of sensory and motor disorders (a decrease in sensitivity in the proximal parts is possible; tendon reflexes may remain intact).

Autoimmune neuropathies

The most common autoimmune polyneuropathies are acute and chronic inflammatory demyelinating polyradiculoneuropathy.

[ 12 ]

Multiple mononeuropathies

Multiple mononeuropathies, or multifocal neuropathies, are based on focal demyelination of individual nerves. EMG reveals blocks of excitation conduction along individual nerves, while adjacent nerves may be intact. Consequently, the characteristic clinical sign of multiple mononeuropathies is asymmetry of the lesion.

Among multiple mononeuropathies, two forms are of particular interest: motor multifocal neuropathy and Sumner-Lewis syndrome.

Multifocal motor neuropathy with conduction blocks

Multifocal motor neuropathy with conduction blocks is an acquired autoimmune demyelinating neuropathy characterized by the development of asymmetric slowly progressive weakness of the muscles of the limbs (usually the arms), fasciculations, cramps and the absence of sensory disturbances. The clinical picture of multifocal motor neuropathy is in many ways similar to amyotrophic lateral sclerosis (isolated motor disturbances without sensory disturbances, tendon reflexes are often preserved), in connection with which the diagnosis of this disease is especially important, since, unlike amyotrophic lateral sclerosis, it is amenable to therapy and has a favorable prognosis for life.

The disease is accompanied by the formation of persistent conduction blocks along the motor nerves in places different from the places of typical tunnel syndromes. A characteristic sign is the preservation of the conduction function of sensory fibers at the site of the conduction block along the motor fibers.

Multifocal acquired demyelinating sensorimotor neuropathy with Sumner-Lewis conduction blocks

The disease is similar in many ways to multifocal motor neuropathy, but it is accompanied by damage to not only motor but also sensory fibers. When examining sensory fibers, a decrease in the amplitude of the sensory response can be detected. Previously, Sumner-Lewis syndrome was considered a variant of chronic inflammatory demyelinating polyneuropathy, but at present it is considered an independent disease. It is believed that the disease has a faster course than multifocal motor neuropathy.

Multiple mononeuropathy due to vasculitis

Vasculitis often clinically causes multiple mononeuropathy of ischemic nature with asymmetrical damage to the nerves of the extremities. Pain syndrome along the nerve is characteristic. EMG reveals axonal changes in clinically affected nerves with preserved conductive function of nearby clinically intact nerves. The diagnosis is clarified by nerve biopsy. Multiple mononeuropathy often occurs against the background of an established diagnosis of a systemic disease. In the case of an unestablished diagnosis, unexplained weight loss, fever, arthralgia, myalgia, night sweats, pulmonary and abdominal symptoms attract attention.

Paraproteinemic polyneuropathies

Clinically, paraproteinemic polyneuropathies resemble chronic inflammatory demyelinating polyneuropathy with predominantly sensory disturbances: paresthesia, hypoesthesia. Motor disturbances are most often moderate. The course of paraproteinemic polyneuropathies is progressive, in contrast to the remitting course of chronic inflammatory demyelinating polyneuropathy. EMG reveals signs of demyelinating polyneuropathy.

Polyneuropathies associated with vitamin B deficiency

Most often, deficiency of B vitamins occurs in people suffering from alcoholism, drug addiction, HIV infection; in patients with gastrointestinal dysfunction, with insufficient nutrition (for example, those following strict diets). With a deficiency of vitamins B ₁, B ₆, B ₁₂, sensorimotor axonal polyneuropathy occurs, starting from the lower extremities. Hypesthesia in the distal parts of the extremities, weakness of the distal muscles of the legs, pain, and burning in the feet are typical. Vitamin B ₁₂ -deficiency polyneuropathy is characterized by impaired deep muscle sensitivity (a consequence of funicular myelosis), cognitive impairment is possible. As a rule, vitamin B ₁₂ deficiency is associated with gastric resection or atrophic gastritis, which results in a disruption of the secretion of Castle's intrinsic factor, and, therefore, is accompanied by gastrointestinal symptoms and pernicious anemia (general weakness, fatigue, pale skin).

Diabetic polyneuropathy

Chronic axonal-demyelinating distal sensorimotor polyneuropathy develops most frequently in diabetes mellitus. The risk of developing polyneuropathy depends on the level of glycemia and the duration of the disease. In type 2 diabetes mellitus, polyneuropathy can be one of the first signs of the disease, therefore, when detecting polyneuropathy of unclear genesis, it is advisable to determine the level of glycosylated hemoglobin or conduct a glucose tolerance test. Less common are proximal diabetic polyneuropathy, acute diabetic polyneuropathy, and autonomic polyneuropathy. Diabetes mellitus also contributes to the development of neuritis and tunnel syndromes. In addition, chronic inflammatory demyelinating polyneuropathy is more common among patients with diabetes mellitus than in the general population.

Chronic distal diabetic polyneuropathy typically begins with a feeling of numbness in the first or third-fifth toes of one foot, then the area of sensitivity disorders increases rather slowly, a feeling of numbness in the toes of the second foot appears, after some time it covers the entire foot and can rise up the shin to the knee level, at this stage a feeling of numbness in the fingertips can join. Pain, temperature, vibration sensitivity is impaired, in the advanced stage of the disease complete anesthesia can develop. Movement disorders are less pronounced. Achilles reflexes disappear early. Neuropathic pains, as a rule, join several years after the onset of polyneuropathy, have a very unpleasant emotional coloring for the patient, are often accompanied by excruciating allodynia and are difficult to treat. Simultaneously with sensory disorders, trophic disorders of the skin of the shins develop, associated with both damage to the vegetative fibers and microangiopathy. Vegetative disorders are not limited to the extremities - diabetes mellitus is characterized by the development of dysautonomia, which manifests itself in insufficient vegetative regulation of internal organs (decreased heart rate variability, tachycardia, orthostatic hypotension, impotence, gastrointestinal dysfunction).

[ 13 ], [ 14 ], [ 15 ]

Uremic polyneuropathy

Uremic polyneuropathy occurs in chronic renal failure with creatinine clearance less than 20 ml/min (usually less than 10 ml/min). Usually, distal sensorimotor polyneuropathy develops. EMG reveals an axonal type of changes with secondary demyelination. The severity of polyneuropathy primarily depends on the duration and severity of chronic renal failure. Uremic polyneuropathy usually begins with paresthesia in the lower extremities, then weakness and atrophy of the distal muscles of the legs, then arms. Characteristics include decreased vibration sensitivity (more than 90% of patients), lack of tendon reflexes (more than 90%), distal hypoesthesia (16%), cramps (67%). Muscle weakness is noted in 14% of patients, it is moderate. In 45-59% of cases, autonomic dysfunction (postural hypotension, dizziness) is possible.

Diphtheria polyneuropathy

Diphtheria usually causes demyelinating sensorimotor polyneuropathy with damage to the cranial nerves. As a rule, polyneuropathy develops 2-4 weeks after the onset of the disease and debuts with damage to the cranial nerves, primarily the bulbar group, and the oculomotor, facial and optic nerves may also be involved in the process. Later, sensorimotor neuropathy develops in the extremities with damage to the distal and proximal muscles. In severe cases, the ability to move independently is lost, and weakness of the respiratory muscles occurs, which may necessitate artificial ventilation.

[ 16 ], [ 17 ], [ 18 ], [ 19 ], [ 20 ]

HIV-associated neuropathies

HIV infection may cause various types of peripheral nerve damage. The disease may proceed as a distal symmetrical polyneuropathy characterized by paresthesia, dysesthesia, and a feeling of numbness in the feet, gradually spreading to the hands. HIV-infected individuals are more likely than the general population to develop Guillain-Barré syndrome and chronic inflammatory demyelinating polyneuropathy. In some cases, multiple mononeuropathies develop.