From the Research
Natural spinal fusion at the C4-C5 level can potentially cause lower extremity weakness, although this is not the most common presentation, as evidenced by a case report of a 38-year-old man with severe C6-C7 spinal stenosis presenting with progressive numbness, weakness, and severe spasms in both lower extremities 1. When the C4-C5 vertebrae fuse naturally, it primarily affects the cervical spine region, which typically manifests as neck pain, stiffness, and possibly upper extremity symptoms. Lower extremity weakness would more likely occur if the fusion leads to secondary complications such as spinal stenosis, disc herniation, or if it alters the biomechanics of the spine, placing stress on the thoracic or lumbar regions. The mechanism involves compression of the spinal cord at or below the fusion site, affecting the long descending motor tracts that control the lower limbs. This compression can develop gradually as the altered mechanics of the fused segment cause accelerated degeneration of adjacent segments or if the fusion itself creates a kyphotic deformity that narrows the spinal canal. Some key points to consider include:
- The importance of comprehensive neurological evaluation, including MRI imaging, to assess for cord compression in patients experiencing lower extremity weakness
- The potential for secondary complications, such as spinal stenosis or disc herniation, to contribute to lower extremity weakness
- The role of altered spine biomechanics in placing stress on the thoracic or lumbar regions, potentially leading to lower extremity weakness Patients experiencing lower extremity weakness should undergo comprehensive neurological evaluation including MRI imaging to assess for cord compression, as early intervention may prevent permanent neurological damage, as highlighted in a study on the causes of lower extremity weaknesses after posterior lumbar spine fusion surgery 2. Treatment options range from conservative management with physical therapy to surgical decompression depending on the severity of symptoms and evidence of progressive neurological deterioration. It is essential to consider the cervical spine in the evaluation of lower extremity symptoms, as demonstrated by a case report of a patient with cervical myelopathy presenting with lower extremity weakness and autonomic dysfunction 1. In clinical practice, it is crucial to prioritize a thorough evaluation and consider the potential for cervical spine involvement in patients presenting with lower extremity weakness, even if the primary complaint is not related to the cervical region.