What is the Achilles reflex: problems, absence, decrease, loss and closure

The tendon that runs from the back of the leg down the shin to the beginning of the foot was named after the legendary warrior Achilles; his feet were very vulnerable. The Achilles reflex is an involuntary flexion of the foot that occurs when this tendon is affected. It is formed in a child only at seven days of age.

The neonatologist records the formation of the reflex by lightly hitting the Achilles ligament with a percussion hammer. The triceps surae muscle reacts to the mechanical impact, it contracts, and then the feet reflexively flex.

Methodology

The most common method of examination in an outpatient setting is this: the subject kneels on a couch or chair so that his feet hang freely and without tension over the edge, his hands rest against the wall or hold the back of the chair. In this position of the patient, the examiner strikes the heel tendon with a hammer.

To examine the patient in the prone position: both legs of the subject are bent at right angles at the knee and ankle joints. With one hand, the examiner holds the foot with his left hand by the toes (it is more convenient to approach from the patient’s right side), with the other he hits the heel tendon with a hammer.

To examine a patient in a supine position, the examiner grabs the foot with his left hand, bends the patient’s leg at the knee and hip joints, dorsiflexes the foot, and then strikes with a hammer [1].

Provocateurs of foot diseases

Uncomfortable shoes contribute to inflammation and tendon injuries.
The risk of tendon and joint pathologies is increased by:

• decrease in tissue elasticity caused by age-related changes;
• excessive motor loads leading to tendon damage;
• some forms of flat feet, accompanied by hyperpronation, in which the foot turns inward when walking;
• uncomfortable shoes leading to improper load distribution.

If you are at risk, take care of high-quality shoes and proper rest after exercise, otherwise one day you will have to treat damaged tendons and joints for a long time and painfully.

Achilles reflex. Concept, diagnostic methods and its importance

The Achilles reflex is caused by hitting the Achilles tendon with a hammer, resulting in contraction of the triceps surae muscle and plantar flexion of the foot. The most common way to induce a reflex is the following: the subject kneels on a couch or chair so that his feet hang freely; with his hands he rests against the wall or holds on to the back of a chair.

The examiner applies successive blows with a hammer to the left and right Achilles tendons.

Zh. Babinsky suggested inducing the reflex in the position of the subject on his back; The lower limb is bent at the hip and knee joints with outward rotation, then the foot is dorsiflexed and the Achilles tendon is struck with a hammer. Sometimes the reflex is induced in the position of the subject on his stomach: both feet are grabbed by the toes (the limbs are bent at the knee joints), held in an average position between flexion and extension, and the tendons are struck with a hammer.

This technique of inducing a reflex is convenient when examining children. Reflex arc: sensory fibers of the tibial nerve, sciatic nerve, I-II sacral segments. The reflex is deep, tendon, physiological.

Appears on the 7th day of life. The Achilles reflex decreases or disappears with tabes dorsalis, polyneuritis, lumbosacral radiculitis, damage to the spinal roots and other diseases of the peripheral nervous system.

When the pyramidal tract is affected, it increases, often turning into foot clonus. First described by the Polish neurologist J.

Babinski in 1879. To study Achilles reflexes, the subject is asked to kneel on a couch or chair so that his feet hang freely, without tension, it is best to rest his palms on the wall or hold on to the back of the chair with his hands. Hitting the Achilles tendon with a hammer causes a reflex.

The blow must also be precise and of equal force, so that there is no false difference in reflexes.

The knee and Achilles reflexes are the most constant of all tendon reflexes and therefore their absence becomes significant.

It should be recalled that reflexes can be inhibited by muscle tension.

Using the method of distraction, it is sometimes possible to obtain very lively tendon reflexes where at first they could not be evoked at all. Often, to distract attention, Jendraszek's technique is used, which consists in asking the subject to clasp the bent fingers of one hand with the fingers of the other and forcefully pull his arms to the sides.

You can ask the patient to look up, clench his teeth tightly, count, answer questions, etc.

The loss of knee and Achilles reflexes due to defects in the pupils and disorder of their reactions to light resolves the issue of the presence, most often, of tabes dorsalis. Their absence may indicate a previous history of polyneuritis or poliomyelitis (sometimes some paretic or atrophic phenomena in the feet remain).

Occasionally, loss of reflexes (usually Achilles) is a symptom of myelodysplasia, i.e., a congenital defect in the development of the spinal cord, accompanied by loss of plantar reflexes, sometimes a deep arch of the foot, claw-shaped toes (Friedreich's foot), cold cyanotic feet, etc.

As a rare case, the loss of knee and Achilles reflexes as a completely isolated symptom can be caused by the congenital absence of tendon reflexes in a completely healthy and normal nervous system.

Characteristic

A reflex arc is a nerve pathway in the human body that connects muscle groups without affecting the brain. Pathways control involuntary movements in response to a specific stimulus. One example is rapid eye blinking in response to dust in the air, coughing when food gets stuck in the windpipe, or kicking the center of the knee. Reflex arcs are completely independent of the paths along which most nerve impulses travel. But the messages they convey are just as important, so impaired reflexes often signal serious problems with neural control and muscle support.

The arches are usually located in the spine or brain, although there is no conscious control at either location. Reflex arcs are shorter than longer nerve pathways. Those in the spine control the responses of the large muscles of the arms and legs, and those in the brain are associated with responses in the face.

The doctor palpates the Achilles tendon just above the back of the heel bone. It is the strongest and largest tendon in the human body and attaches the superior triceps muscle (soleus and gastrocnemius) to the calcaneal tubercle. The tendon is covered by the paratenon, a thin sheath that reduces friction and also serves as a conductor for blood vessels.

The Achilles reflex (the reflex arc consists of sensory and motor fibers of the tibial nerve) is called the ankle reflex test. This is a deep tendon response that can be easily evoked using a standard instrument, the reflex hammer. The Achilles tendon test is a simple and effective part of a complete lower extremity examination and physical screening of the nervous system.

Problems of the Achilles reflex: absence, decrease, loss and closure

Typically, congenital areflexia is complete, i.e., reflexes in the upper extremities are also lost. Loss of knee and Achilles reflexes with preserved upper extremity reflexes is always suspicious.

Essentially, always in the absence of knee and Achilles reflexes, the patient must be thoroughly examined, preferably in a hospital, an X-ray of the lumbosacral spine, an analysis of cerebrospinal fluid and blood for the Wasserman reaction and other studies are required.

“Topical diagnosis of diseases of the nervous system”, A.V.Triumfov

Almost most often, changes in the reactions of the pupils signal tabes dorsalis, progressive paralysis, cerebral syphilis or epidemic encephalitis (parkinsonism).

In the first case, after the discovery of the Argyll-Robertson symptom, attention should have been directed to other manifestations, such as: a decrease in superficial (usually pain) sensitivity at the level of the nipples (DV), loss or lethargy (sometimes only unevenness) of the Achilles and knee reflexes, “ rheumatism" (shooting…

To study the movements of the eyeballs, the doctor moves his finger to the right, left, up and down, and the patient follows the finger with his gaze all the time.

In this case, damage to one or another eye muscle or gaze paresis may be detected. The same technique also detects nystagmus, which is most often horizontal and is thus detected when looking to the sides...

The values ​​of uneven facial innervation should not be overestimated. Cases of congenital asymmetry are so common that it is very rare that we see a face with perfect symmetry. If slight unevenness of innervation of the face is a single symptom, then it is regarded as “physiological” asymmetry.

The same should be said regarding the deviation of the tongue to the side when protruding it, if this is a single symptom. Tongue deviation...

The fastest method of studying reflexes is carried out in this way: the patient continues to stand in front of the doctor, the latter grabs with his left hand both hands of the person being examined by the ends of the fingers so that the arms are bent at the elbow and wrist joints.

Next, it is proposed to relax the muscles of the arms, while they should be completely passive and held in this position not by muscle tension, but by the hand...

To study abdominal reflexes, the subject lies on his back.

Abdominal reflexes should not be examined in an upright position. In a calm position of the body and with relaxed abdominal muscles, line irritations of the same strength and speed, completely symmetrical, are applied to the skin of the abdomen.

To obtain upper abdominal reflexes - below and parallel to the lower edge of the costal arches, for middle abdominal reflexes - strokes...

ACHILLES REFLEX

- plantar flexion of the foot during percussion with a hammer on the heel (Achilles) tendon. It is one of the normal tendon reflexes.

Symptoms of Achilles reflex disorders

Dysfunction of the damaged limbs is reflected in the corresponding symptoms, which bother a person when walking, performing normal movements, and working with heavy objects.

The main symptoms are:

• pain in the sacral region;
• numbness of the legs;
• constant freezing of feet;
• excessive muscle reactions;
• disruption of the reflex arc up to nerve paralysis;
• lack of support on the forefoot;
• decreased muscle tone;
• atrophy of the triceps muscle;
• lameness when walking.

Treatment is aimed at restoring impaired functions and restoring the conduction of nerve impulses. During therapeutic and even surgical treatment, the Achilles tendon reflex may not recover.

Achilles reflex reflex arc

The reflex arc passes through the sciatic nerve, closing at the level of the V lumbar, I and II sacral spinal segments.

The Achilles reflex is induced in the position of the subject being examined on his knees with his feet dangling (Fig.) or in a supine position, then it is necessary to slightly bend the leg at the hip-femoral and knee joints, keeping the foot slightly bent to the dorsal side. The Achilles reflex decreases or disappears with various organic diseases that disrupt its arc (trauma, inflammatory, tumor, degenerative processes in the caudal spinal cord, cauda equina, sciatic nerve).

When the pyramidal system of the Achilles is damaged, the reflex increases, and foot clonus is often noted.

See also Reflex, Tendon reflexes. V. V. Mikheev.

Method for inducing the Achilles reflex. The dotted line shows plantar flexion of the foot with a positive Achilles reflex.

Description of the Achilles reflex

What does the Achilles tendon look like?
The definition of “Achilles reflex” in medicine refers to a reflex contraction of the muscles on the calves of the legs - tricipitis surae, which occurs simultaneously with the plantar response to a hammer blow on the points of the heel tendon. This reflex has a deep physiological nature.

The Achilles reflex circuitry involves the response to an external stimulus of the muscle and tendon tissues from the knee ligaments, through the calf muscles and tendons on the outside of the heels.

A simple reflex arc, the pattern of which is closed in the tissues of the central nervous system, improves a person’s adaptation to the environment: we involuntarily withdraw our hand from a hot iron, the size of the pupils is adjusted when the light changes, etc.

The Achilles reflex is part of the group of constant physiological responses of the body to external stimuli. It has been thoroughly studied by physicians and is well presented in educational and methodological literature for medical schools.

Anatomy and structure

The Achilles tendon, or calcaneal tendon, is a strong band of fibrous tissue that connects the calf muscles to the heel bone. The gastrocnemius and soleus muscles combine into one band of tissue that becomes the Achilles tendon at the lower end of the lower leg. It is then inserted into the heel bone.

The heel tendon is the largest and strongest connective tissue formation in the body. When the calf muscles flex, bundles of collagen fibers pull on the heel. This movement allows you to rely on your toes when walking, running or jumping. Despite their strength, the fibers are vulnerable to injury due to the limited blood supply and the high stress they experience.

The Achilles tendon is innervated by the S1 and S2 tibial nerve roots. The tendon reflex is a stretch response that refers to the involuntary contraction of a muscle in response to passive stretch.

When the tendon is tapped with a reflex hammer, the triceps muscle is lengthened (stretched) and the following chain of actions occurs:

• Stretch receptors in the muscle spindle are activated and excitatory stimuli are transmitted.
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• The stimulus is carried by afferent neurons (Ia) to the spinal cord.
• Afferent neurons synapse and activate alpha motor neuron in the ventral horn of the spinal cord.
• The activated alpha motor neuron transmits the efferent stimulus back to the neuromuscular junction of the agonist muscle (triceps), resulting in muscle contraction (reflex).

To ensure that the agonist muscle (triceps surae) of the reflex has unimpeded contraction, Ia afferent neurons simultaneously stimulate an inhibitory neuron in the spinal cord, which prevents the antagonist muscle from contracting.

Spinal reflex arcs bypass the brain to enable rapid response.

But the descending corticospinal tracts coming from the cerebral cortex weaken and reduce the amplitude of the reflex arc. The S1 nerve root serves as a conductor of both afferent (reacting to various stimuli) and efferent (transmitting signals) impulses of the reflex arc of the Achilles tendon.

The deep tendon reflex arc is divided into an upper motor neuron (UMN) component and a lower motor neuron (LMN) component. The UMN component consists of descending structures: the corticospinal tract, brainstem, internal capsule, and cerebral cortex. LMN structures are the ventral (anterior) horn of the spinal cord and the peripheral nerve that innervates the muscle. The LMN of the Achilles reflex consists of the ventral horn of the S1 nerve root and the tibial nerve.

Possible diseases and pathologies

The Achilles reflex (the reflex arc does not directly affect the brain) is interpreted and scored based on the miotic reflex scale.

It uses a rating system from 0 to 4:

Additionally, a plus (+) or minus (-) can be added to the numerical score to determine the intermediate stage. A score of 5 can also be used to indicate sustained clonus of >10 rhythmic oscillations following rapid muscle stretch.

Reflexes can also be diagnosed descriptively:

• absent;
• hypoactive;
• normal;
• hyperactive.

Testing deep tendon reflexes gives the doctor information about the state of the motor nerves, the forms of synaptic connections in the spinal cord, and descending motor conductors. Lesions of the upper motor neuron, UMN, cause an overactive reflex, while lesions of the lower motor neuron, LMN, cause hypoactive reflexes. During the examination, any asymmetric increase or decrease in reflexes is noted.

Lack of ankle response can be associated with over 47 different diagnoses.

Achilles reflex reflex arc

Some of them:

• Poisoning with medicine or alcohol.
• Familial genetic disorders.
• Spina bifida.
• Vitamin E deficiency.
• Injuries, such as concussions.

When examining deep tendon reflexes, it is critical to compare each reflex response with its corresponding opposite side. Hyporeflexia, hyperreflexia, and asymmetrical responses are abnormal and require further evaluation.

Hyporeflexia

A decreased muscle reflex usually indicates a disorder of the LMN. Disease or disorder of the LMN causes a decreased or absent reflex because the stimulus is not transmitted to the effector muscle. Additional signs of the disease include lethargy or decreased muscle tone, weakness, twitching and muscle atrophy.

Causes of LMN disease include:

• Acquired peripheral neuropathies.
• Physiological disorders caused by diabetes mellitus, hypothyroidism, uremia, vitamin deficiencies, electrolytes and toxins such as lead or arsenic.
• Drugs such as isoniazid, vincristine, and diphenylhydantoin are known to cause hyporeflexia.
• There are many hereditary and immune-related causes: spinobulbar muscular atrophy, spinal muscular atrophy, distal hereditary motor neuropathies and Guillain-Barré syndrome.
• Structural damage to the LMN components of the tibial nerve can occur with foramen stenosis or intervertebral disc herniation at the L5-S1 level that compresses the S1 nerve root.

Hyperreflexia

An increased muscle reflex indicates diseases caused by UMN pathology. Damage to any of the motor neuron components (corticospinal tracts, brainstem, internal capsule, and cerebral cortex) results in an overactive deep tendon reflex due to disinhibition of the spinal reflex arc.

As described previously, upper motor neurons play an important role in suppressing the reflex response. In addition to hyperreflexia, UMN lesions manifest as spasticity or increased muscle tone, weakness, and various pathological reflexes.

The causes of UMN damage can be caused by:

• anoxic brain damage (encephalopathy);
• brain or spinal cord injury;
• cerebrovascular (pathology of cerebral vessels) disorders;
• neurodegenerative disorders (amyotrophic lateral sclerosis, primary lateral sclerosis, multiple sclerosis);
• spinal cord compression;
• malignant neoplasms.

The reflex response of the neural arch during the Achilles reflex test is used in some cases to identify various syndromes and disorders.

Thyroid dysfunction

Among the many methods developed to study thyroid function, two that examine peripheral aspects are discussed: Achilles tendon-bone reflex (timing of contraction and relaxation of the calf muscle) and the cardiovascular response to thyroid hormones.

In people with hypothyroidism (lower function), relaxation occurs slowly. Water, sodium and calcium are excreted more slowly in hypothyroidism. The heart muscle also relaxes slowly, which contributes to heart failure because the heart cannot receive as much blood as a normally relaxed heart. Blood vessels in hypothyroidism cannot relax properly, which contributes to hypertension.

Adi syndrome

A neurological disease that affects the pupil of the eye and the autonomic nervous system. This affects the reflexes of both the pupil and the deep tendons. The pupil of one eye, which is larger than normal, slowly constricts in bright light. This occurs along with the absence of deep tendon reflexes, usually in the Achilles tendon. The disease begins gradually in one eye and often progresses to involve the other eye.

It may initially cause loss of deep tendon reflexes on only one side of the body, but then progresses to the other side. Eye and reflex symptoms may not appear at the same time. People with Adi syndrome may also sweat excessively, sometimes on only one side of the body.

The combination of these three symptoms—abnormal pupil size, loss of deep tendon reflexes, and excessive sweating—is commonly called a variant of Adie's syndrome. Some patients may develop cardiovascular problems. The condition appears alone or in combination with other diseases of the nervous system, such as Sjögren's syndrome or migraines.

Diabetes

In case of long-term diabetes mellitus, diabetic polyneuropathy develops. It is a debilitating disease that affects nearly 50% of diabetic patients. The main types of diabetic neuropathy are sensorimotor and autonomic.

When sensory nerves are damaged, the nerves with the longest axons are affected first. Evaluation for sensorimotor neuropathy reveals loss of Achilles tendon and patellar reflexes, ataxia (impaired muscle coordination) of gait, and balance problems.

The Achilles tendon reflex is a simple technique for detecting the reflex arc response and is part of any neurological examination of the lower extremities. It can be performed both in a clinic and in a hospital setting. However, differences in technique and levels of experience of the healthcare professional may lead to different results.