Distal Baclofen Pump Catheter Migration Associated with Far‐Lateral Paraspinal Surgical Placement

Objectives. The increased rigidity and spasms implicit to patients being treated with baclofen provide a potential source of drug delivery system–related complications. Placement of the intrathecal catheter from the far‐lateral paraspinal approach has been advocated to avoid catheter fracture as previously reported with a midline approach. A thin fascial layer and increased muscle bulk laterally could increase motion of catheters placed in this position. The authors report on a series of patients found to have spinal catheter migration out from the thecal sac following a far‐lateral paraspinal surgical approach. Materials and Methods. The medical records of six consecutive patients who required revision of an intrathecal baclofen infusion system secondary to spinal catheter migration were included in this retrospective review. Each patient failed to respond to oral antispasmodic therapy and showed a positive response to a trial of intrathecal baclofen before initial pump implantation. Clinical notes and operative reports were reviewed. Results. All patients had a baclofen pump inserted with the intrathecal catheter placed through the far‐lateral portion of the paraspinal musculature entering above the lumbar vertebral pedicle. In all cases, the spinal catheter migrated and was found coiled outside of the thecal sac. In two patients, this occurred on two separate occasions. Mean time to catheter revision following implantation was 7 ± 2 months. Conclusions. Spinal catheter migration from the subarachnoid space can occur with intrathecal baclofen infusion systems. Alternative methods for spinal catheter placement warrant further study.     

Multiple granular cell tumors are an associated feature of LEOPARD syndrome caused by mutation in PTPN11

We report a patient with a clinical and molecular diagnosis of LEOPARD syndrome (LS) associated with multiple granular cell tumors (MGCT). Bidirectional sequencing of exons 7, 12, and 13 of the PTPN11 gene revealed the T468M missense mutation in exon 12. This mutation has been previously reported in patients with LS. To our knowledge, this is the first report of MGCT associated with molecularly characterized LS and provides the first molecular evidence linking granular cell tumors (GCT) to the Ras/mitogen-activated protein (MAP) kinase pathway. We propose that MGCT can be associated with LS. Analysis of GCT from this case tested negatively for loss of heterozygosity (LOH) at the PTPN11 and NF1 loci and did not show deletions of the PTEN gene. The absence of LOH of PTPN11 supports published functional data that T468M is a dominant-negative mutation.