Sciatic Nerve Injury - Causes, Complications, Diagnosis, and Management

What Is Sciatic Nerve Injury?

Sciatic nerve injury is caused due to trauma to the sciatic nerve. This injury may cause symptoms such as paraesthesia, loss of muscle power, and pain. These symptoms are similar to those symptoms caused by sciatica. Sciatica is a debilitating condition where the patient experiences pain and weakness in the distributed regions of the sciatic nerve.

Where Does the Sciatic Nerve Originate and Distribute?

The sciatic nerve is the longest and thickest nerve in the body. This nerve comprises five nerve roots, two from the lower back region called the lumbar spine and three from the final spine section named the sacrum. The five nerve roots combine, forming the right and left sciatic nerve. The lateral structures of the sciatic nerve are the greater sciatic foramen which is inferior to the piriformis where the sciatic nerve emerges. The medial structures of the sciatic nerve include internal pudendal vessels, inferior gluteal vessels and nerves, and the pudendal nerve. This sciatic nerve crosses the ischium’s posterior surface and runs through the obturator internus, quadratus femoris, and Gemeli. The sciatic nerve divides into common peroneal and tibial branches. Symptoms of nerve damage may occur on one side or both sides of the body.

What Are the Causes of Sciatic Nerve Injury?

The main causes lying behind sciatic nerve injury are trauma, hip dislocation, and acetabular fracture. The other iatrogenic causes are faulty positioning during anesthesia, tourniquet placement, dressing, faulty fitting orthotics, and radiation.

Trauma to the sciatic nerve might also occur due to injection injuries. Injection palsy is the other name of injection injury. Injection palsy occurs due to intramuscular injection given at the gluteal site. Injection palsy causes loss of movement or lack of sensation at the affected lower extremity with or without pain.

Injection palsy can begin suddenly or after hours of experiencing damage to the sciatic nerve. A misplaced intramuscular injection in the gluteal region serves the common cause. It might also occur due to frequent injections or poor techniques used by inadequately trained technicians.

Older people are more prone to develop injection-induced sciatic nerve injury due to their decreased muscle mass or the presence of other debilitating diseases. In a total hip replacement procedure, nerve compression and stretching during surgery can cause damage to the sciatic nerve and result in dysfunction.

The sciatic nerve may also become damaged due to a herniated disk in the spine or overgrowth of bones in the vertebrae. More rarely, the sciatic nerve can be compressed by a tumor or damaged by a disease called diabetes.

Piriformis syndrome develops when the piriformis muscle causes spasms. It puts pressure and irritates the sciatic nerve causing pain and numbness on the back of the leg and foot. Cauda equina is a rare condition that affects the bundle of nerves below the spinal cord called the cauda equina, and this condition might also cause sciatic nerve injury rarely.

What Are the Risk Factors for Sciatic Nerve Injury?

Certain habits and conditions increase the risk of developing sciatic nerve injury. The risk factors are,

Age-related changes in the spine.

Obesity.

An occupation that makes a person carry heavy loads or drive a motor vehicle for long periods.

Prolonged sitting or following a sedentary lifestyle.

Diabetes.

What Are the Clinical Features of Sciatic Nerve Injury?

Partial damage to the sciatica nerve causes weakness of knee flexion, difficulty in bending the foot inward (inversion), or bending the foot down.

The other features noticed are:

Foot drop.

Wasting of the calf muscles.

Loss of Achilles tendon reflex.

Sensory loss below the knee and development of trophic ulcers.

Some people may also face an absence of sweating in the sites of sciatic nerve distribution. The skin of the affected part may become thin, shiny, and edematous.

How to Diagnose Sciatic Nerve Injury?

Sciatic neuropathy is the differential diagnosis given for sciatic nerve injury. The doctor performs a thorough physical examination, discusses the symptoms experienced by the patient, and conducts diagnostic studies to pinpoint the cause behind sciatic nerve dysfunction. The diagnostic studies include electromyography and magnetic resonance imaging.

How to Treat Sciatic Nerve Injury?

• Usually, sciatic nerve pain may last from one to two weeks. Sciatic nerve injuries can be medically managed through non-steroidal anti-inflammatory drugs, opioids, and myorelaxants, but they show less response to these medicines. A recent study showed the use of Methylprednisolone through intravenous and oral routes in managing neuropathic pain.

• Previously, Methylprednisolone was given through trans sacral block, which effectively worked on reducing neuropathic pain presenting with motor and sensory deficits. Surgery is advised for patients who have sustained injection palsy for more than three months. Patients with foot deformity are advised for Achilles tendon lengthening, osteotomy, and capsulotomy. The other procedures done are neurolysis and grafting with clinical and electrophysiological monitoring.

• Physical therapy is the first-line approach advised for patients suffering from sciatic nerve injuries. Pain management involves using TENS (transcutaneous electrical nerve stimulation), massage, gentle stretching, and desensitization techniques.

• The effectiveness of physical therapy to improve nerve regeneration after nerve damage remains uncertain. In case of extensive injuries, exercise will not be the first line of treatment. Hence, exercise prescription should be based only on the quality and intensity of exercise rather than exercise volume.

• Joint or soft tissue mobilization retains the flexibility of the muscles, nerves, and soft tissues and prevents deformity. TENS (transcutaneous electrical nerve stimulation) and electro-acupuncture enhance nerve regrowth. Biostimulation laser therapy and magnet therapy also help in nerve regeneration and lessen muscle atrophy.

• Bracing might be needed in the early stages of sciatic nerve injury to prevent deformity and other associated risks. An example is the use of an ankle-foot orthosis (AFO), which prevents foot drop and skin damage.

• Depending on the outcome, the affected person may still need bracing for a short period. Physiotherapists should evaluate the treatment given to the patient thoroughly.

• Good clinical judgment, decision-making skills, and experience of a physiotherapist are essential for the effective rehabilitation of a patient.

Conclusion:

Sciatic nerve injury is a debilitating condition that results in sciatica. The sciatic nerve is the longest and thickest nerve in the body. It runs through the hips, buttocks, down the legs, and below the knees. Sciatic nerve injury affects a person with its unique causes and symptoms. This condition is treatable once the affected person seeks the doctor as early as possible when he starts experiencing the symptoms of sciatic nerve damage.