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Radial nerve paralysis is a common neurologic condition that can occur in cats, often secondary to trauma. In this condition, a nerve responsible for innervation of the front limb becomes damaged, leading to a temporary or long-term abnormality with limb function. Radial nerve paralysis results in the inability for the cat to bear weight on the affected limb. Below is everything you need to know about the signs, causes, and treatment of radial nerve paralysis in cats.
What Is the Significance of the Radial Nerve?
It is important to understand general anatomy and neurology prior to learning what it means to have radial nerve paralysis. First, the central nervous system consists of the brain and spinal cord. Nerves branching from the spinal cord are considered peripheral nerves. The brachial plexus is a group of nerves located in the armpit area of cats that originate from the neck region of the spinal cord. One of the nerves within the brachial plexus is the radial nerve.
The radial nerve innervates muscles within the lower limb that cause extension of the wrist and digits (the triceps muscle), which is responsible for the extension of the elbow and provides sensation to the front of the limb and top of the foot.
In radial nerve paralysis, something has occurred, generally trauma, which has damaged the nerve altering its function completely or partially.
What Causes Radial Nerve Paralysis?
Radial nerve paralysis occurs typically due to trauma. Damage to nerves can be due to compression, tearing, or stretching of the nerve or nerves. The trauma can be done to the brachial plexus or specifically to the brachial nerve.
Examples of trauma leading to radial nerve damage include vehicular accidents and hanging injuries where a cat is suspended by the front limb, often involving the entire brachial plexus. Uncommonly, tumors can form causing compression of the nerve, leading to innervation abnormalities. Radial nerve paralysis refers to the loss of nerve function.
Classification of Nerve Injury
Nerve injuries can involve different components of the nerve structure. Prognosis and function are dependent on the level of damage incurred by the nerve.
- Neuropraxia is when nerve function is temporarily lost without physical changes to the nerve. Recovery from this type of paralysis is likely.
- Axonotmesis refers to the partial severance of nerve fibers that are still protected by an outer covering. In patients experiencing this type of nerve damage, recovery may occur. Recovery is slow as it takes a long time for nerve fibers to regrow.
- Neurotmesis is when the entire thickness of the nerve is severed. This does not provide the nerve with a path in which to follow for nerve regrowth. As a result, recovery from this type of nerve damage is unlikely to occur.
Diagnosing Radial Nerve Paralysis
Consultation With a Veterinarian
If your cat has endured an injury or has become lame, it is important to seek veterinary care. Your veterinarian will perform a physical examination to better determine if the abnormal gait is secondary to orthopedic, soft tissue, or neurologic concerns. Consultation with a veterinarian neurologist may be recommended to further evaluate and diagnose radial nerve paralysis.
Diagnostics
- Radiographs may be recommended to identify any broken bones that could be negatively impacting the nerves. Additionally, it is necessary to rule out orthopedic reasons for lameness.
- Electrodiagnostic tests can be used by neurologists to identify possible nerve abnormalities through the conduction of electrical impulses.
- MRI may be utilized if there is suspicion of brachial plexus injury. The MRI can show how significant the damage is, although it is not helpful with an evaluation of the nerves further down the limb.
What Are the Signs of Radial Nerve Paralysis?
- Relaxed or “dropped” elbow
- Knuckling over the wrist
- Inability to bear weight on the affected limb
- Wounds on the top surface of the foot
- Muscle atrophy of the limb
- Complete or partial inability to extend the toes, wrist, elbow
Radial Nerve Paralysis Treatment
Appropriate pain medications and anti-inflammatories may be necessary. Reconstruction of nerves is not commonly practiced in veterinary medicine as it is in human medicine, although in cases of clean transection of the nerve, it may be recommended. Stem cell therapy is not widely reported in veterinary medicine.
Physical rehabilitation is recommended for pets. This may include passive range of motion and stretching exercises. Physical therapy can help prevent ligament and tendon contracture. Laser therapy also appears beneficial.
Some injuries will improve with time, depending on the severity of the injury. Unfortunately, some cats may not experience improvements and secondary trauma may occur secondary to dragging the foot. In these cases, amputation of the limb may be recommended. Fusion of the carpus, or wrist, has been done to help preserve the limb, but outcomes are usually not ideal.
How to Care for a Cat With Radial Nerve Paralysis
Cats with radial nerve paralysis may require varying levels of treatment and care. Some injuries may heal with time, depending on the severity of the injury. In other cases, damage to the nerve may be irreversible. If the limb is given time to heal on its own, it is important to physically protect the limb from trauma if it is being dragged on the ground. Protecting the affected limb may include the use of a bootie or socks.
Your cat may benefit from long-term pain medications. It will be important to maintain a good relationship with your veterinarian so they can help guide you regarding recommended therapy. Veterinarians can provide owners with recommended massage techniques and stretches to help prevent contracture of the limb.
Frequently Asked Questions
Will My Cat Need to Have Their Leg Amputated?
Not all patients with radial nerve paralysis will require amputation. Amputation will be dependent on if use of the affected limb improves with time, or if the paralysis causes significant secondary trauma.
Should I Pursue Physical Rehabilitation for My Cat?
Yes, absolutely! If you are able to provide physical rehabilitation, the prognosis may be improved depending on the level of nerve damage present. Additionally, physical rehabilitation helps to prevent limb contracture. Acupuncture is also beneficial and may provide pain relief as well.
In Summary
The radial nerve is a large nerve responsible for innervation of the front limb. Injury to the radial nerve can vary in severity. Veterinary consultation is recommended to help guide treatment and progress. With time, some injuries may improve, but in some patients, amputation of the affected limb may be necessary.
Featured Image Credit: Denys Kurbatov, Shutterstock
