- What is a radial nerve?
- Radial nerve - which muscles does it innervate?
- Radial nerve palsy - causesdiseases
- Radial nerve palsy - symptoms of the disease
- Radial nerve palsy - diagnosis
- Radial nerve palsy - management and therapy
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Radial nerve palsy is called Saturday night palsy in medical jargon. What is this ailment and what are its causes? Is the radial palsy caused solely by an incorrect sleeping position? What symptoms are associated with the palsy of the radial nerve?
What is a radial nerve?
The radial nerve is derived from the brachial plexus, a formation belonging to the peripheral nervous system that arises from the anterior twigs of the spinal nerves (which in turn originate from the spinal cord).
The radial nerve runs initially at the back of the humerus, in the so-called groove of the radial nerve (this is a relatively unfavorable position for it, because in the event of injuries of the humerus - for example fractures, this nerve is damaged).
Then the radial nerve goes to the lateral side of the shoulder, and then, within the elbow joint, it divides into its final branches - that is, a deep branch, which is on the back surface of the forearm, and a superficial branch, which goes to the superficial side of the forearm, and from there to the dorsal side of the hand.
The superficial branch of the radial nerve is divided into the five dorsal nerves of the fingers.
They are responsible for the sensory innervation of the parts of the hand and the dorsal surface of the fingers of the 1st, 2nd and 3rd hand. The radial nerve also sensitively innervates the posterior surface of the upper arm and forearm.
Radial nerve - which muscles does it innervate?
In the context of the symptoms of radial nerve palsy, it is worth looking at the extent of the motor innervation of the radial nerve. The radial nerve innervates the posterior muscle group of the arm and the lateral and posterior muscle groups of the forearm. The radial nerve is therefore primarily responsible for straightening the forearm, straightening the hand and thumb, as well as straightening the fingers in the metacarpophalangeal joints.
The palsy of the radial nerve impairs precisely these ranges of movements, which causes the characteristic symptoms - the so-called drooping hand.
Radial nerve palsy - causesdiseases
Here we come back to the article on Saturday night's electrocution mentioned in the introduction. The most common cause of paralysis of the radial nerve is an incorrect position during sleep - for example, sleeping with the head resting on the shoulder, or incorrect positioning of the hand during anesthesia (during surgery).
The shock of Saturday night is definitely favored by alcohol intoxication, when we do not fully control the position of our body.
This nerve paralysis typically has the characteristics of neuropraxia, i.e. it results only from pressure on the nerve and not from breaking it, which makes it reversible. The opposite of this condition is neurotmesis, i.e. disruption of the continuity of the nerve, leading to a typical nerve paralysis with its full symptoms.
The cause of a radial nerve palsy is not only a bad sleeping position, but also states such as:
- fracture of the humerus - as already mentioned above, the radial nerve runs in the groove on the humerus, therefore breaking it often leads to damage to this nerve,
- Wearing a watch too tightly, but also wearing a handcuffs too tightly, for example - it leads to a strong pressure on the sensory branch of the radial nerve, the consequence of which is numbness in the area of the thumb. In the medical literature, this phenomenon is called Wartenberg syndrome,
- incorrectly selected armpits causing pressure on the nerve,
- hematoma, cyst, or a tumor appearing in the area of the radial nerve, which causes its compression and thus the symptoms of paralysis.
Radial nerve palsy - symptoms of the disease
Radial nerve palsy is characterized by the so-called drooping hand symptom. This clinical situation is characterized by the inability to straighten the arm. Moreover, this paralysis is accompanied by such deviations in the physical examination of the patient, such as:
- impairment of forearm straightening,
- impaired thumb straightening and abduction,
- forearm inversion disorder,
- finger extension disorder in metacarpophalangeal joints.
In the so-called Saturday night paralysis, the functions of the triceps muscle - the triceps (which is also to some extent motor innervated by the radial nerve) are preserved because this muscle is innervated by a branch of the radial nerve that separates from the main nerve even before the radial nerve furrow of the humerus, thanks to which it is not exposed to pressure.
Please be aware that the symptoms of a radial palsy are dependentfrom the level at which the nerve described in this article is damaged. If the damage occurs at the level of the axillary fossa, we will additionally deal with impaired motor functions of the triceps muscle of the arm (i.e. the triceps).
Radial nerve palsy - diagnosis
The first step in the diagnosis of palsy is a thorough physical examination of the patient. The doctor can assess the motor activity of individual muscles of the upper limb, as well as the presence of sensation in a given area, and on this basis suspect paralysis of a specific nerve.
A more advanced diagnostic test is an electromyographic test (EMG for short). It consists in testing the activity of a selected muscle by stimulating it through electrical stimulation. Such a test allows to assess whether the excitation is properly conducted through a given nerve.
If the nerve is intact, then the contractile response of the given muscle group is correct. During EMG, a special electrode is used, which is placed around the selected nerve (usually through the skin).
Radial nerve palsy - management and therapy
If the cause of the radial nerve palsy is compression caused by a tumor, cyst or hematoma, a surgical consultation and removal of the lesion contributing to the symptoms are necessary. In some situations it is necessary to properly position the limb with elements such as a sling or kinesiology taping. Proper positioning of the limb prevents stretching of the affected muscles.
In order to prevent muscle atrophy, electrostimulation of paralyzed muscles is used. Electrostimulation leads to contractions of specific muscles, which as if forces the muscles to work and thus protects against atrophy. In some cases, specialists also recommend supplementation with B vitamins, which supports the regeneration of the peripheral nervous system.
You should be aware that in order to restore the function of peripheral nerves, and thus - for the proper functioning of the muscles, it is necessary to conduct properly selected rehabilitation. Depending on the patient's condition, the following can be used:
- physical treatments,
- and hydrotherapy.
Kinesiotherapy is a form of rehabilitation which consists in performing appropriate movement exercises under the supervision of a physiotherapist. Treatment and rehabilitation of peripheral nerve palsy requires time and patience, both on the part of the doctor and physiotherapist, and the patient himself.