BACKGROUND: Lumbar spinal stenosis (LSS) is a prevalent degenerative condition, particularly in individuals over 65, and is a leading cause of disability and spinal surgery in this population. The hallmark symptom is neurogenic claudication, but severe cases may present with focal motor deficits, such as foot drop. While open decompressive surgery remains the standard for patients with progressive neurological deficits, minimally invasive techniques, like the minimally invasive lumbar decompression (MILD®, Stryker Medical, Kalamazoo, MI) procedure, have emerged as alternatives, especially for patients with ligamentum flavum hypertrophy. However, the efficacy of MILD in cases with motor weakness remains underexplored.

CASE REPORT: A 70-year-old woman with prediabetes, osteopenia, and depression presented with 9 months of frequent falls, progressive unsteady gait, and left ankle dorsiflexion weakness. Imaging revealed severe central canal stenosis at L2-L3 and L4-L5, with significant ligamentum flavum hypertrophy. Despite recommendations for open decompression, the patient declined surgery due to anesthesia concerns. She was managed conservatively with a walker and ankle-foot orthosis (AFO), but developed a heel pressure ulcer. Four months after symptom onset, she underwent a left-sided, image-guided MILD procedure at L4-L5. The procedure was completed without complications. At 2 weeks postprocedure, she discontinued AFO use, with marked improvement in ambulation and muscle strength. By 6 weeks, left ankle dorsiflexion had normalized, and at 12 weeks, she was nearly symptom free. At one-year follow-up, she maintained full motor recovery and did not require open surgery.

CONCLUSIONS: Our case demonstrates that early use of the MILD procedure may facilitate rapid and durable motor recovery in selected patients with LSS and focal motor weakness due to ligamentum flavum hypertrophy. The MILD procedure offers a lower-risk alternative to open surgery, with significant improvements in function and quality of life. Larger studies are warranted to further validate its role in this patient population.

KEYWORDS: MILD, MILD®, foot drop, lumbar spinal stenosis, spinal stenosis