Diagnosis and Surgical Treatment of Extraforaminal Root Compression of the Fifth Lumbar Spinal Nerve

Extraforaminal stenosis at the lumbosacral junction is less common than intraspinal canal lesions, and the radiological diagnosis is less established. We present 10 cases that presented with neurological deficits compatible with a diagnosis of L5 radiculopathy, such as sensory disturbance in the L5 area associated with neurogenic claudication. Radiography demonstrated lumbar scoliosis and wedging of the L5-S1 intervertebral space in 6 patients, and transitional vertebra (Castellvi types IB, IIA, and IIB) in 6 patients. Computed tomography demonstrated marked osteophyte formation at the posterolateral margin of the L5-S1 vertebral bodies in all 10 patients. Coronal constructive interference in steady-state magnetic resonance imaging showed extraforaminal entrapment of the L5 root. Decompression procedures included partial resection of the L5 pars interarticularis, sacral ala, and L5 transverse process along the L5 spinal nerve. Osteophytes of the L5-S1 vertebral bodies were also resected in 6 patients because they limited mobility of the nerve roots. Complete decompression was achieved with posterior bone resection in the other 4 patients. Pain relief was achieved in all patients. Our results demonstrate that simple decompression surgery using a surgical microscope is an effective and less invasive surgical option for patients with extraforaminal compression of the fifth lumbar spinal nerve at the lumbosacral junction.