Sciatica or Pinched Nerve? How to Tell the Difference

Join this channel to get access to perks: https://www.youtube.com/channel/UCOHfqHMhHvfQCYJDXfpSAiw/join Pain radiating to the lower extremity can result from disc herniation, lumbar radiculopathy, or sciatica. However, numerous other conditions can mimic the symptoms of lumbar radiculopathy, leading to similar clinical presentations. Physicians should consider alternative diagnoses when patients present with lower extremity pain that mimics sciatica or disc herniation. Disc herniation typically presents with a distinct symptom pattern, so it is important for the clinician to differentiate true sciatica from conditions that imitate it. Peripheral nerve entrapment syndromes in the lower extremity can closely resemble lumbar radiculopathy or disc herniation. Several types of lower extremity entrapment syndromes exist. One such condition that mimics lumbar radiculopathy is compression neuropathy. Patients reporting these symptoms may mistakenly attribute them to a spinal issue or believe they have a disc herniation. Compression neuropathy refers to the compression of a peripheral nerve in the lower extremity, resulting in symptoms that resemble sciatica or nerve root irritation. For instance, compression of the common peroneal nerve often arises due to trauma around the knee. A ganglion cyst is also a major cause of peroneal nerve compression. The common peroneal nerve has two branches: The superficial peroneal nerve, which provides sensory input to the dorsum of the foot and innervates the peroneal muscles. The deep peroneal nerve, whose compression leads to weakness of the tibialis anterior muscle. Weakness of the tibialis anterior can result from either L4 or L5 radiculopathy. Thus, compression of the deep peroneal nerve at the knee, or compression of the L4 or L5 nerve roots at the spine, can both cause tibialis anterior weakness and potentially foot drop. The L5 nerve root also innervates the gluteus medius muscle. Therefore, if foot drop is due to L5 radiculopathy, there will likely also be weakness of the hip abductor muscles in approximately 85% of cases. However, if foot drop is caused by peroneal nerve neuropathy, there should be no associated ipsilateral hip abductor weakness, since the pathology is distal and does not involve the nerve root. This distinction helps differentiate between peripheral nerve and nerve root involvement. If foot drop is associated with ipsilateral hip abductor weakness → most likely L5 radiculopathy. If foot drop occurs without hip abductor weakness → most likely peroneal neuropathy. In such cases, examine the knee for: A palpable mass A positive Tinel’s sign at the proximal fibula If the patient presents with foot drop, obtain an MRI of the lumbar spine. If the MRI is inconclusive, perform an EMG. EMG and nerve conduction studies help differentiate proximal (nerve root) from distal (peripheral nerve) etiologies—particularly when spinal imaging is nondiagnostic. Examine the short head of the biceps femoris: If involved → suggests proximal cause If unaffected → indicates a distal lesion, below its level of innervation If lumbar MRI is normal and EMG supports compression neuropathy of the peroneal nerve at the knee, obtain an MRI of the knee to assess for a ganglion cyst or other compressive lesions. Superficial peroneal nerve entrapment typically occurs due to a fascial defect about 12 cm proximal to the lateral malleolus, where the nerve exits the anterolateral leg fascia. The mechanism of injury often involves an inversion injury combined with a fascial defect. Patients report numbness and tingling over the dorsum of the foot, worsened by plantarflexion and inversion. Treatment includes observation or fascial release in more resistant cases. Deep peroneal nerve compression may occur due to: Inferior extensor retinaculum Osteophytes over the talonavicular joint This is known as anterior tarsal syndrome, presenting with: Pain in the dorsum of the foot Radiation to the first web space Positive Tinel’s sign over the deep peroneal nerve Tarsal tunnel syndrome involves compression of the posterior tibial nerve at the tarsal tunnel. This leads to burning pain and paresthesia in the plantar aspect of the foot, with a positive Tinel’s sign over the tibial nerve. Imaging and nerve studies confirm the diagnosis. Lateral femoral cutaneous nerve compression causes anterolateral thigh paresthesia and is termed meralgia paresthetica. This nerve is purely sensory and arises from L2-L3 nerve roots. It may be mistaken for radiculopathy at these levels. The nerve travels beneath the inguinal ligament, where it may become compressed. Symptoms include: Numbness or burning along the anterior thigh Often relieved by sitting External compression (tight belts or jeans), obesity, diabetes, pregnancy, or prolonged prone positioning during surgery are contributing factors. Presence of hip flexor weakness is more consistent with L2-L3 radiculopathy than with meralgia paresthetica.