From the Guidelines
Dorsal foot paresthesias in L5 nerve root compression are caused by compression of the L5 nerve root, which can result from a herniated disc, spinal stenosis, or other mechanical pressures.
Key Points
- The L5 nerve root is responsible for controlling great toe and foot dorsiflexion strength 1.
- Compression of the L5 nerve root can cause sensory impairment, weakness, or diminished deep tendon reflexes in the distribution of the L5 nerve root, including the dorsal foot 2.
- A focused examination, including straight-leg-raise testing and a neurologic examination, can help assess the presence and severity of nerve root dysfunction 1.
- Herniated discs are a common cause of L5 nerve root compression, with more than 90% of symptomatic lumbar disc herniations occurring at the L4/L5 and L5/S1 levels 1.
- Spinal stenosis can also cause L5 nerve root compression, resulting in symptoms such as neurogenic claudication 2, 3.
From the Research
Causes of Dorsal Foot Paresthesias in L5 Nerve Root Compression
- Dorsal foot paresthesias in L5 nerve root compression can be caused by various factors, including disc herniation, central and lateral spinal stenosis, and extraforaminal compression of the L-5 nerve root at the lumbosacral junction 4, 5.
- The "double crush" phenomenon, where multiple locations of nerve compression occur, can also account for persistent lower limb paresthesia, even after spinal neural decompression surgery 6.
- Meralgia paresthetica, a compression neuropathy of the lateral femoral cutaneous nerve, can produce similar symptoms to L4 or L5 radiculopathy and should be considered in patients with obesity and diabetes who have chronic irritation of the ventrolateral areas of the thigh 7.
- The distribution of pain and paresthesias in L5 nerve root compression does not always correspond to traditional dermatomal patterns, making diagnosis and treatment challenging 8.
Factors Contributing to Extraforaminal Compression of the L-5 Nerve
- Disc herniations, bony compression (osteophytes or sacral ala), and ligamentous compression (sacroiliac ligament and lumbosacral band) can contribute to extraforaminal compression of the L-5 nerve 5.
- Disc space collapse or coronal wedging can also narrow the extraforaminal space and contribute to nerve compression 5.
- Associated conditions, such as foraminal stenosis, adjacent-level disease, and spondylolisthesis, can also be present in patients with extraforaminal compression of the L-5 nerve 5.