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Sciatic nerve injury occurs due to trauma (pressure, stretching or cutting) to the nerve and can cause symptoms such as paresthesias, loss of muscle power and pain. These symptoms are similar to those caused by sciatica, however the term 'sciatica' is typically used to refer to conditions where the sciatic nerve is irritated or compressed, rather than being injured directly.
Aetiology
- • Trauma - hip dislocation, acetabular fracture
- • Iatrogenic causes -
- - Direct surgical trauma
- - Faulty positioning during anesthesia
- - Injection of neurotoxic substances
- - Tourniquets
- - Dressings, casts or faulty fitting orthotics
- - Radiation
Iatrogenic causes of Sciatic Nerve Injury.
Trauma to the sciatic nerve through
- • Injection injuries - also referred to as injection palsy via intramuscular injection at gluteal region (dorsogluteal site). It describes a situation where there is a loss of movement and or lack of sensation at the affected lower extremity with or without pain.
- • Total Hip Replacement - nerve compression and stretch during surgery causing damage to the sciatic nerve that serves the majority of muscle groups in the lower limb, resulting in dysfunction. Reported at a level of 1%
Clinically Relevant Anatomy
The sciatic nerve is the longest nerve in the human body (with nerve root L4, L5, S1, S2, S3) and is the continuation of the sacral plexus. The sciatic nerve is the most lateral structure emerging through the greater sciatic foramen inferior to the piriformis. Medial to it are: inferior gluteal nerve and vessels; the internal pudendal vessels; the pudendal nerve. It crosses the posterior surface of the ischium then crosses: Obturator Internus, Gemelli, Quadratus Femoris and descends on Adductor Magnus. The sciatic nerve divides into its terminal branches, the tibial and common peroneal nerves, usually just below the mid-thigh, although a higher division is not uncommon.
Epidemiology/Aetiology
Injection palsy can begin suddenly or hours following damage to the Sciatic Nerve. A misplaced intramuscular injection at the gluteal region is the most common cause of injury and it is attributed to either frequent injections or poor techniques as a result of inadequately trained staff or unqualified staff. It affects more males than females with a ratio of 2.7:1. Within a period of two years, Pakistan recorded annual incidence of six (6) million children.
Clinical Presentation/Characteristics
The common symptoms are pain and abnormal gait pattern. However, pain intensity is difficult to quantify or rate particularly in the pediatric population but facial expression is quite helpful. Others clinical signs include:
- • Foot drop
- • External rotation and abduction contracture of the hip
- • Equinovarus or Equinus deformity
- • Muscular weakness/atrophy
- • Motor and sensory deficit such as paraesthesia and numbness
Diagnostic Procedures
Sciatic neuropathy is more of a clinical diagnosis. Well detailed subjective and objective examination is the golden rule. Electro-diagnostic studies include;
- • Electromyography
- • Magnetic Resonance Imaging
Medical Management
In most cases, symptoms of Sciatic Nerve injury does not respond to the use of non steroidal anti-inflammatory drugs (NSAIDS), opioids and myorelaxants. However, the use of methyl prednisolone via transcaral block was effective to manage the neuropathic pain, motor and sensory deficits. In addition, a recent study showed beneficial use of methyprednisolone via both intravenous and oral routes.
Surgery is opted for patients that did not improve beyond 3 months of sustaining injection palsy. Common procedures include neurolysis and grafting with serial clinical and electrophysiological monitoring. Patients with foot deformity can opt for elongation of the tendon Achilles, osteotomy and capsulotomy. Although, there are conflicting findings comparing conservative and surgical interventions.
Physical Therapy Management
Conservative means is the first line approach for the management of patients with sciatic nerve injury
- Pain Management. Use of TENS, massage, gentle stretching and desensitization techniques could be employed.
- Exercise Prescription: A muscle should not be exercised till some muscle strength has returned and nerve generation is occurring. It is important to delay resistance exercises till sufficient nerve healing has occurred. If you are progressing too quickly pain levels may increase and or tingling / numbness during exercise. Nerve injuries that are recovering handle low intensity exercises better than high so keep the intensity low with 25 reps rather than the traditional 10 reps at higher intensity.
- Electrical Muscle Stimulation: TENS and Electroacupuncture have been shown to help enhance nerve regrowth.
- Bio-laser Stimulation. Can help with nerve nutrition and regeneration.
- Magnetotherapy Can assist in nerve regeneration and lessen muscle atrophy.
- Joint or Soft Tissue mobilisation. To retain flexibility of muscle, nerve and soft tissue and prevent deformity.
- Balance Training. Co-ordination, strength and flexibility loss leads to reduced balance.
- Splinting. In the early stages following injury, bracing may be needed to prevent deformity and associated risks, e.g. Ankle Foot Orthosis (AFO) to prevent foot drop, skin damage and falls risk. Depending on the final outcome some form of bracing may still be needed.