Administration of intrathecal injections should always be attempted through an ultrasound (US)-guided procedure in patients with spinal muscular atrophy (SMA), according to a study recently published in the Orphanet Journal of Rare Diseases.

“Given its safety and efficacy, real-time US guidance is recommended for SMA patients with spine surgery or severe scoliosis, and the near-spinous process view can be used as an interlaminar puncture approach for US guidance,” the authors wrote.

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This prospective study included 7 patients previously diagnosed with SMA. Mean age was 14.14 years. Most participants had undergone spinal fusion, while 2 presented with severe scoliosis.

The median time from spinal surgery to the intrathecal administration of the drug was 5 months, ranging from 1 to 23 months. Only 3 participants had a lumbar laminotomy in L3-L4. The most frequent SMA subtype was 2a SMA in 3 individuals, followed by 1c SMA and 3a SMA in 2 individuals each.

In total, the researchers performed 20 US-guided lumbar punctures, achieving a 95% success rate. The only procedure that was unsuccessful was later attempted through computed tomography (CT) guidance, with success. Almost all (89.5%) cases required 2 or less insertions, and the operation time ranged between 13 and 56 minutes, with a median of 19 minutes.

Regarding adverse events after the procedure, only 3 patients experienced them. The most common adverse event was postpuncture headache, present in 2 cases, followed by transient leg numbness and lumbar pain in 1 case each.

These findings suggest that all patients with SMA could benefit from this approach, especially since individuals usually require multiple administrations of nusinersen, the medication preferred for this disease. A US-guided injection could yield high success with a favorable safety profile compared to other alternatives.

“CT guidance and fluoroscopic guidance are often used for these patients to assist with lumbar puncture, but long-term radiation exposures are expected, especially for children,” the authors noted.


Wei C, Liang Z, Wu Y. Ultrasound-guided interlaminar approach for nusinersen administration in patients with spinal muscular atrophy with spinal fusion or severe scoliosis. Orphanet J Rare Dis. Published online February 17, 2023. doi:10.1186/s13023-023-02630-8