Translaminar Approach for Treatment of Hidden Zone Foraminal Lumbar Disc Herniations: Surgical Technique and Preoperative Selection of Patients with Long-Term Follow-Up.

BACKGROUND: Lumbar disc herniation is a common degenerative disease of the lumbar spine with a prevalence of 1%-3% in some population studies. In 10% of patients, there is a fragment migrated cranially in Macnab's "hidden zone." In selected cases, this fragment can be removed with a translaminar approach that was described in 1998. We provide a detailed description of the technical advantages and pitfalls of the translaminar approach in a consecutive series of 32 patients treated at our institution.

METHODS: Patients were divided preoperatively and postoperatively into 5 classes based on the Oswestry Disability Index (ODI): class 1, ODI 0%-20% (minimal disability); class 2, 20%-40% (moderate disability); class 3, 40%-60% (severe disability); 60%-80% (crippled); 80%-100% (bedridden or disabling symptoms).

RESULTS: Four (12.5%) patients were upgraded 1 ODI class after the operation; 6 (18.7%) patients were upgraded 2 classes, 8 (25%) patients were upgraded 3 classes, and 11 (34.4%) patients were upgraded 4 classes. In 3 (9.4%) patients, ODI class did not change after the operation. After surgery, 7 (21.9%) patients developed mild low back pain. Mean follow-up was 25 months.

CONCLUSIONS: When performed by dedicated spinal neurosurgeons, the translaminar approach is safe and effective in patients with long-term follow-up. Most patients showed an improvement in ODI. Major pitfalls were related to surgical selection and the narrow working space.