Introduction
The anterior lobes of the lumbar and sacral spinal cords come together to create the lumbosacral (LS) plexus, a network of nerves. Damage to the lumbar and sacral plexus nerves is known as LS plexopathy. It is less frequent than brachial plexopathy, though. Leg and low back pain are frequently prevalent in LS plexopathy patients. They may also develop sphincter dysfunction, motor weakness, and other sensory complaints, including numbness and paresthesia. Diabetes mellitus, severe damage, neoplasms, and pregnancy are major etiologies that can result in LS plexopathy. Depending on the underlying condition, treatment is frequently restricted and varies greatly. Debilitating LS plexopathy can have a negative impact on a patient's quality of life. To lower morbidity and mortality, early detection and care are essential.
What Is Lumbosacral Plexus?
A network of nerve fibers supplies the lower limb muscles called the lumbosacral plexus. It originates in lower back and splits into branches down the legs and in front of hip joint. Pain and weakness in the lower back are symptoms of lumbosacral plexus damage, which can occur before birth or as a result of trauma. This may feel tingly, scorching, or cramping.
What Are the Causes of Lumbosacral Plexus Injury?
As the LS plexus is located close to the abdominal and pelvic organs, several diseases and accidents can cause LS plexopathy. They consist of:
Direct Trauma
- Hip dislocation to the back.
- Broken sacrum.
- Lumbar plexus block.
Autoimmune, Inflammatory, and Metabolic Factors
- Type 2 diabetes.
- Amyloidosis.
- Sarcoidosis.
Abscess and Infections
- Osteomyelitis of the spine.
- Persistent tuberculosis and fungal infections.
- Further infections include Herpes zoster, HIV (human immunodeficiency virus) or AIDS (acquired immunodeficiency syndrome), and Lyme disease (HZ).
- A psoas abscess.
Radiotherapy of Abdomen and Pelvis Cancer
Pregnancy-Related
- Due to birth stress, they typically happen in the third trimester and following delivery.
Injury to the LS Plexus’s Innervating Vascular System
- Catheterization of the femoral vessel.
- Ischemia from direct compression brought on by aortic dissection, retroperitoneal hematoma, arterial pseudoaneurysms, etc.
Postoperative Plexopathy
- After gynecological and other pelvic procedures, scar tissue growth and hematomas may develop.
What Are the Signs and Symptoms of a Lumbosacral Plexus Injury?
The lumbosacral plexus can get injured for several reasons. They include traumatic events like an accident, labor that lasts a long time during childbirth, cancer, diabetes, and autoimmune diseases. Moreover, several cardiac operations may harm nerves. The major symptoms of lumbosacral plexus injuries include:
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Low back and buttock pain that travels down the leg.
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Sensory alterations of the foot.
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Muscle weakness in the outer thigh.
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A throbbing ache at the front of the thigh originates in the pelvis.
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Diabetics with thigh and hip discomfort and acute weakness.
When the pain subsides, weakness develops, and the reflexes slow down. Extreme weakness often worsens for 3 to 10 days before regressing over the following several months.
How to Diagnose Lumbosacral Plexus Injury?
The diagnosis is based on presenting illness, medical history, traumatic history, and recent trauma to the pelvis. The other major diagnostic criteria involve:
Imaging:
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MRI (Magnetic Resonance Imaging): The best test for assessing the LS plexus is an MRI with gadolinium contrast. MRI is recommended at the initial assessment of LS plexopathy associated with neoplasms.
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Positron Emission Tomography (PET): The complete extent of the malignancy will be determined by positron emission tomography (PET). Also, it assists with illness staging, future therapy, and prognosis.
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MR Neurography: Compared to conventional MRI, MR neurography is a suitable method for LS plexopathy assessment. The extraspinal injuries that are causing neuropathic leg pain can be identified with neurography.
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CT (Computed Tomography): A computed tomography (CT) scan can be used in situations when an MRI is contraindicated (for example, if the patient has an incompatible pacemaker).
Electrodiagnostic Studies: To assist in distinguishing lumbosacral plexopathy from other kinds of neuropathy or radiculopathies, electrodiagnostic procedures like electromyography (EMG) are effective. Neurological damage can be located with the use of electromyography. EMG can also be used to distinguish between cancer and radiation-induced plexopathy. Patients with contraindications to EMG might be diagnosed with the help of magnetic nerve root stimulation (e.g., bleeding disorders). There are situations when using magnetic root stimulation to analyze nerves more thoroughly have been described.
Laboratory Investigations: A complete blood count with an erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), coagulation analyses, autoantibody testing (antinuclear antibodies - ANA), antineutrophil cytoplasmic antibodies (ANCA), anti-syndrome-related Sjogren's antigen A, anti-Ro/anti-La antibodies and hemoglobin A1c are suggested blood tests to determine the etiology in patients with LS plex. In certain situations, it may also be required to perform serum protein electrophoresis (SPEP), ACE levels, HIV, Lyme antibodies, rapid plasma reagin (RPR), and Epstein-Barr virus (EBV) serology.
What Are the Treatment Options for Lumbosacral Plexus Injury?
LS plexopathy treatment is based on the underlying cause. Analgesics and muscle relaxants are used to treat symptoms. Physiotherapy may occasionally be used in combination to treat the symptoms. When diabetes is the underlying problem, corticosteroids are frequently recommended. Non-steroidal anti-inflammatory medicines (NSAIDs), Pregabalin, Gabapentin, Duloxetine, Amitriptyline, and opioids reduce the symptoms. Malignant tumors are surgically removed and treated appropriately. Considering a dorsal rhizotomy may be a consideration in situations with severe symptoms. It has been demonstrated that rhizotomy significantly lowers pain and opioid consumption in this group.
Another successful therapy involves injecting nerve blockers into the lumbosacral plexus using ultrasonography. They numb the damaged nerves, preventing pain from spreading to the limb.
What Is the Prognosis of Treatment?
The underlying etiology, its responsiveness to therapy, and the timing of therapeutic intervention all affect the prognosis. Patients with retroperitoneal hematoma, diabetic amyotrophy, and LS plexopathy related to pregnancy had favorable prognosis. Most individuals with pregnancy-related LS plexopathy fully recover their symptoms within two to six months after birth. However, LS plexopathies caused by trauma are typically thought to have a poor prognosis
Conclusion
A multidisciplinary team of healthcare providers, such as a primary care physician, physical therapist, radiologist, pain medicine specialist, neurologist, obstetrician, neurosurgeon, or psychiatrist, is required to manage LS plexopathy. Without effective therapy, the morbidity rate of LS plexopathy increases. Management after the first diagnosis can be challenging. Additionally, counseling is advised for comorbid depression or anxiety.
