Lumbar laminotomy for the intrathecal administration of nusinersen for spinal muscular atrophy: technical note and outcomes

Nusinersen (Spinraza) is a US Food and Drug Administration-approved intrathecal medication for the treatment of spinal muscular atrophy (SMA). Adult patients with SMA often undergo thoracolumbar fusion to treat neurogenic scoliosis, preventing thecal access. The authors report a laminotomy technique and the ease of intrathecal access in three SMA patients with prior thoracolumbar fusions. Patients were positioned in the lateral decubitus position or prone. Lumbar laminotomy was performed below the conus, between the lateral longitudinal rods, to preserve mechanical stability. Fluoroscopy provided real-time identification of instruments. Hardware was contoured with a carbide drill bit to develop the surgical window. Fiducial screws were placed along the perimeter for demarcation. Sublaminar wire removal caused dural defects that were repaired with a layer of dural substitute onlay and sealant. All patients successfully received nusinersen thecal injections via lumbar puncture by an interventional radiologist. Fluoroscopy time ranged from 6 to 36 seconds. No postoperative pseudomeningoceles, cerebrospinal fluid leaks, or wound complications occurred. For patients with SMA and posterior fusion from prior scoliosis treatment, lumbar laminotomy is an effective method for creating thecal access for the administration of nusinersen.