RESUMEN
Foraminal disc herniation is considered to be a part of extreme lateral disc herniations which have relatively frequent occurrence of about 10% of all lumbar disc herniations. It presents a different clinical feature from that of usual intraspinal disc herniation, in that the prolapsed foraminal disc material compresses the nerve root at the level of disc herniation. Previously many operative procedures for foraminal disc herniations have been introduced with the aids of various diagnostic methods. Intervertebral foraminotomy and total facetectomy are still the most widely used options in treating extreme lateral lumbar disc herniation. But these techniques could result in an unfortunate structural disruption and frequently cause spinal instability and continued postoperative back pain. Recently unilateral partial hemilaminectomy and resection of spinous process followed by discectomy were performed in our hospital. For this procedure, paraspinal muscles were elevated subperiosteally and retracted bilaterally exposing the spinous process and laminae on both sides. After the unilateral partial hemilaminectomy and resection of spinous process preserving articular facet joint, then obliquely downward looking through intervertebral foramen allowed direct visualization of prolapsed foraminal disc and compressed nerve root. Thereafter prolapsed foraminal disc could be successfully removed under direct vision with the preservation of spinal stability. When extraformainal disc coexisted, intertransverse approach was additionally performed.