One-sided hanging stop: causes, symptoms, diagnosis

A one-sided hanging stop may have a peripheral or central origin, and on this basis, it is necessary to consider the various causes of the onset of this condition. The main issue - peripheral or central - is not always easy to solve. Many patients underwent conservative or even prompt treatment for intervertebral disc herniation, although in reality there was central monoparesis due to ischemic stroke or paralysis of the crossed legs.

I. Peripheral:

1. Compression neuropathy (paralysis of the crossed legs).
   1. Inflammatory or neoplastic lesions of the external surface of the lower leg and the Baker cyst of the knee joint.
      1. Traumatic injury of the peroneal nerve.
   2. Iatrogenic paralysis due to incorrect intramuscular injection.
      1. Herniated disc (radiculopathy L5).
2. Diabetic and alcoholic neuropathy.
3. Syndrome of the anterior tibial artery.

II. Central:

1. Ischemic heart attack and brain tumor.
2. Postpristupny paresis.

The following symptoms will help differentiate central and peripheral lesions:

Circumduction (circular motion of the leg) due to increased extensor tone points to the central paresis, which can be observed already at the patient's entrance to the room. Excessive lifting of the leg indicates peripheral paresis.

Level of reflexes: a high achilles reflex is observed when the central motor pathways are affected, a decrease or absence of a reflex indicates abnormalities in the peripheral reflex arc. When the peroneal nerve is affected or the focus is limited to the L5 spine, it is not necessary to expect changes in the reflexes. The answer in the form of plantar extension may be absent or be fuzzy in the central hanging foot.

More difficult to assess are:

Muscle tone, which is often unchanged and does not correspond to the expected pattern, when its increase indicates a central pattern, and a decrease - about peripheral lesion levels. Muscular atrophy, which can not be expected with an acute hanging stop.

Distribution of sensitivity disorders, if any. The main rule is that one-sided violations of the "stocking" type are more characteristic for central lesion, in contrast to the well-known peripheral segmental types of disorders.

Of course, electromyography and investigation of the rate of excitation along the nerve is extremely useful. However, in many cases the solution can be found or prompted without additional examinations.

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I. Hanging stop of peripheral origin

If the peripheral nature of the lesion is established, then to determine its level, it is necessary to assess whether the drooping of the foot and fingers is isolated, or there is weakness in the other muscles. The same question can be formulated in another way: whether the lesion is confined to the peroneal nerve or extends to the tibial nerve. Thus, the defeat of the muscles innervated by a single lumbar spine or two adjacent roots can be established even before EMG, but this requires detailed examination and anatomical knowledge. Assessment of the onset of the disease - acute or gradual - is also very useful (see below).

Differential diagnosis includes the following conditions:

Compression neuropathy

"Paralysis of the crossed legs." This compression neuropathy of the peroneal nerve, including the superficial and deep branches, which is accompanied by sensitive disorders, such as tingling paresthesias and hypoesthesia. Although the cause is the repeated pressure on the peroneal nerve just below the knee in people who are in the habit of sitting in a leg-to-foot position, the onset of weakness is usually acute. A detailed medical history is necessary. This same syndrome develops with a prolonged forced stay in the squatting position. A study of the speed of the conduct on the nerve confirms the diagnosis, revealing the block of conduct in the place of injury.

There are patients who are prone to compression paralysis, and this condition can be familial ("paralysis from compression"). It is necessary to ask about such cases of acute transient weakness, for example, occurring in the defeat of the ulnar nerve. In order not to miss these really rare cases, it is necessary to clarify the family history, it is advisable to investigate the speed of carrying out other nerves to detect a general slowdown in the speed of the exercise. If possible, examine the patient's relatives.

Inflammatory or neoplastic lesions of the external region of the lower leg and the Baker cyst of the knee joint. The fibular nerve can be affected by an inflammatory or neoplastic process on the lateral surface of the tibia (compression-ischemic neuropathy of the common peroneal nerve of Guillain de Céza-Blondin-Valter, professional paralysis of tulip bulb tulips). The syndrome is usually manifested by pain along the side of the shin and foot, hypesthesia in the zone of innervation of the nerve and weakness of the peroneal group of muscles. Neuroma or Baker's cyst of the knee joint is another rare cause of damage to this nerve. The first diagnostic step is to establish the level of lesion close to the fibula in neurological examination and to study the speed of the nerve. X-ray and ultrasound examinations are usually mandatory, but these additional methods can be properly applied only when localization is established clinically.

Traumatic injury of the peroneal nerve

Any kind of knee injury or proximal fracture of the fibula may lead to damage to the peroneal nerve, and in these cases it is easy to establish a diagnosis. In contrast, compression of the nerve from the cast is often overlooked by a physician who does not pay attention to the patient's complaints about paresthesia and pain on the rear of the foot between the first and second fingers, or on the weakness of the extension of the first finger (peroneal neuropathy).

Iatrogenic paralysis due to incorrect intramuscular injection. Another example of iatrogenic damage is an incorrect intramuscular injection in the gluteal region. The division of the sciatic nerve into its main branches, peroneal and tibial nerves, sometimes occurs quite high, so that only the peroneal nerve is affected. About 10% of patients do not experience paresthesia and pain during or immediately after injection, and the onset of weakness can be delayed. There is an easy way to differentiate the lesion at the level of the lumbar spine with a dislocation along the sciatic nerve. Lumbar roots do not carry sympathetic fibers to innervate the sweat glands. They leave the spinal cord no lower than the level of L-2, and connect with the sciatic nerve only in the pelvic region, in the composition of which they go to the periphery. Absence of sweating in the area of innervation of the sciatic nerve or its branches clearly indicates peripheral damage.

Herniated disc

One-sided hanging stop can be a consequence of a herniated intervertebral disc. The onset of the disease is not always sudden and painful, and the presence of tension in the back muscles, a positive symptom of Lasega, is not necessary. If only the fifth lumbar spine (L5 radiculopathy) is affected, then the knee jerk can be preserved, although all the above symptoms are present. Muscles innervated by the fifth root, however, are not identical to those that are provided with the peroneal nerve. Distinguish these conditions can be based on a thorough examination and knowledge of anatomy.

Diabetic and alcoholic neuropathy

Finally, it should be mentioned that there are cases of polyneuropathy when the patient reveals only a one-sided hanging stop, while the defeat of other nerves is subclinical. This is observed in diabetes mellitus and chronic alcoholism. At the same time, there is at least a bilateral reduction of achilles reflexes.

Syndrome of the muscular lodge (anterior tibial artery syndrome)

The name of the syndrome means ischemic damage to the muscles of the long extensors of the foot and toes (muscles of the anterior tibial and common extensor of the fingers). They lie in a narrow canal formed dorsally by the anterior surface of the tibia and ventrally stretched fascia. Overloading these muscles can lead to swollen swelling. Since the fascia limits space, swelling leads to compression of the capillaries and, finally, to ischemic necrosis of the muscles along with ischemic injury of the anterior tibial nerve. A similar mechanism (edema and ischemia of the muscle tissue) is observed with excessive muscle strain, for example, during a game of football or during long walking.

When examined, the painful edema of the prebial region and the subsequent weakness of extension, which increases to full within a few hours, are revealed. As a rule, there is no pulsation on the dorsal artery of the foot. The diagnosis should be established before the onset of muscle paralysis, since only surgical treatment is effective - extensive dissection of the fascia for decompression.

To the hanging leg can also lead also lumbar plexopathy.

II. Hanging stop of central origin

Several described cortical and subcortical lesions may manifest as a drooping foot.

Ischemic heart attack and brain tumor

An acute onset implies the development of an ischemic infarct, while chronic development is characteristic of a brain tumor. The level of blood pressure can be misleading, since primary patients or metastatic brain tumors can also develop in hypertensive patients. On the other hand, headache and cognitive impairment may occur only at a late stage of growth of the brain tumor. Thus, it is always necessary to assume both alternatives and to perform, if possible, a neurovisualizing examination. Given the possibilities of treatment, this measure is fully justified.

Post-run paresis

Any transient weakness can be a post-paroxysmal phenomenon in cases where the epileptic attack (partial or generalized) has not been recognized. In these cases, the serum creatine kinase level is often increased. Focal signs during or after an attack should prompt a careful search for volumetric or vascular lesions of the brain. Justified the search for epileptic activity on the EEG.