Anatomy-Lexicon

The hand of the oath

definition

In the typical position of the oath hand, the thumb, index and middle finger are stretched and the ring finger and little finger are bent.
In medicine, the hand of oath is a symptom that occurs due to paralysis of the median nerve. The hand can no longer be clenched into a fist. If the patient is asked to make a fist, the thumb, index and middle fingers remain stretched, like a hand in an oath.

Accompanying symptoms of a hand of oath

The failure of the flexor muscles of the thumb, index and middle finger results in an oath hand. This is caused by damage to the median nerve. In addition to the flexor muscles in the hand, the median nerve supplies other muscles as well. These are also affected by the damage. Above all, a failure of the other thumb muscles is clinically noticeable. Patients can no longer grip a bottle tightly. The opposition between the thumb and the little finger, i.e. the opposition of the thumb to the other fingers, is also limited.

There are also sensitivity disorders. The median nerve supplies the skin on the inside of the hand of the thumb, index and middle finger, as well as the fingertips of these fingers, also on the outside of the hand.

On this subject, read our article on: Hand pain

Pain in an oath hand

Damage to the median nerve that leads to the formation of an oath hand is always associated with pain. Nerve pain is not necessarily comparable to other pain, such as a sore throat or toothache. Rather, they are often described as burning and shooting in. Especially in the area of the hand that is sensitively supplied by the median nerve, painful paresthesia and numbness occur.

Deafness in an oath hand

In addition to innervating the muscles in the hand, which are required to flex the thumb, index and middle fingers, the median nerve also supplies parts of the hand with sensitivity. As already described, this also applies to the thumb, index and middle finger on the inside of the hand and the fingertips of these fingers on the outside of the hand.
These areas need the median nerve in order to be able to pass on their sensitive information to the brain. If the median nerve is damaged, these areas are perceived as numb.

Read more on this topic at: Hand falls asleep at night - causes and treatment

Treatment of an oath hand

Ultimately, it depends on what the cause of the paralysis of the median nerve is. If it is a temporary pressure injury while sleeping, no treatment is necessary. Then the symptoms are only temporary.

If an upper arm fracture is the trigger for the damage to the nerve, this upper arm fracture must be treated (usually surgically). This also applies to cuts or fractures in the elbow area. Additional measures are immobilization of the arm and physiotherapy.

In rare cases, direct treatment of the nerve injury is possible by means of nerve sutures, i.e. suturing the nerve together surgically. If there is a long-term defect, an attempt can even be made to bridge it with a nerve transplant.

How long do my complaints last?

Most of the time, the hand of the oath is a persistent, i.e. permanent, symptom. If the nerve is irreversibly damaged, the hand of the oath is permanent. Of course, modern neurosurgical operations such as a nerve suture can be tried. But not all patients can restore the original nerve function in this way.

The symptoms only recede spontaneously if there is short-term pressure damage to the nerve as a trigger for the oath hand. In this case, the nerve has not been completely severed and it can regenerate more easily. A spontaneous improvement is possible.

Is it possible to heal the hand of the oath?

There is no cure from the hand of the oath. One can try to perform a nerve suture using modern neurosurgical operating techniques. Longer defects can also be overcome with a nerve transplant. However, it remains to be said that the function does not come close to the intact nerve.

In addition, it is crucial how long the nerve paralysis has existed. With increasing duration there is a regression of the muscles (atrophy) in the hand, especially on the ball of the thumb. An improvement in the function is certainly possible through operational measures. However, one cannot speak of a cure.

Cause of damage to the median nerve

The median nerve is a nerve that contains nerve fibers from the spinal cord segments C6 to Th1. It arises from the brachial plexus, a plexus of nerves on the neck. If the nerve is damaged relatively high up in its course, it comes to the hand of oath.

The cause of nerve paralysis can be in the area of the upper arm, e.g. in the case of a humerus fracture (fracture of the upper arm bone). Even during sleep, pressure from the humerus on the nerves can cause damage. This also applies to the elbow area. Here, too, traumatic causes such as fractures or cuts play a role.

The median nerve can also be damaged in its further course along the forearm through the carpal tunnel. But then there is no longer an oath hand because the nerve on the forearm already divides into a motor and sensitive branch. Only the sensitive branch pulls through the carpal tunnel. Therefore, if the forearm is damaged, the flexors of the thumb, index and middle fingers will not fail. In this case, the fist can be closed without any problems.

Please also read our article on the Carpal tunnel syndrome

The diagnosis of an oath hand

The diagnosis can be made relatively easily using various criteria.

On the one hand, it is important to ask about some points (anamnesis):

Is there any evidence of damage to the median nerve in its course?
Are there any injuries or fractures in the upper extremity?
Are there any accompanying symptoms?

A hand of oath is always associated with sensitivity disorders. In addition to the hand of the oath, there are other clinical signs that can be checked on the physical examination. For example, the bottle symbol is positive. If a muscle in the thumb fails, a round vessel can no longer be completely enclosed. Even pressing the fingertips of the thumb and little finger together does not usually work properly. In addition, there is always device diagnostics such as electroneurography and electromyography.

Measurement of the nerve conduction velocity (NLG)

The nerve conduction velocity is measured using electroneurography (ENG). Here the nerve is stimulated by an electrical stimulus and various parameters can then be derived that allow conclusions to be drawn about the nerve function. A reduced nerve conduction velocity indicates demyelination or a total severing of the nerve.

It is important to do this side-by-side study. In addition, the nerve should be stimulated in several places to determine the level of the damage.