Difficulty of administration of nusinersen in complex-column spinal muscular atrophy: New alternative technique by means of cervical intrathecal access through an Ommaya reservoir.

Background: The study aimed to describe a new Ommaya reservoir implantation method in late-onset SMA patients, assessing its safety and effectiveness under standard clinical conditions.

Methods: Prospective observational study. Lumbar intrathecal access was unfeasible due to significant scoliosis and prior spinal surgeries with instrumentation. Patients were infused with Nusinersen through the Ommaya reservoir at Hospital Universitario La Paz (Spain) following the standard dosing protocol.

Results: The cohort was composed of 6 patients, 5 individuals with type 2 SMA (83.3 %), and 1 patient presenting with type 3 SMA. 4 of the patients were functionally sitters (66.7 %) and 2 had lost this ability prior to initiating treatment (non-sitters). Mean treatment was 34.7 months. Patient discharge was done in all the cases within 48 h post-admission; no significant postoperative complications or during administration of nusinersen were reported. Functional progress was observed in all patients. Hammersmith Functional Motor Scale Expanded (HFMSE) showed a low average increase (1.0), attributed to the severity of baseline functional impairments. Improvements in upper extremity motor function, measured by the Revised Upper Limb Module (RULM), were more pronounced, with an average improvement of 3.3. Disability levels as measured by the Egen Klassifikation 2 (EK2) scale, declined by 4.4.

Conclusion: the current study broadens knowledge regarding the efficacy and safety of using an Ommaya reservoir to administer nusinersen in patients with SMA Types 2 and 3. The technique demonstrated rapid, straightforward drug delivery through a subcutaneous needle, maintaining optimal sterility without radiation or the need for a multidisciplinary team.