Spasticity / Movement Disorders
Kris Foley, MD
Resident
Mount Sinai Hospital
New York, New York, United States
Miguel X. Escalon, MD, MPH
Professor
Icahn School of Medicine at Mount Sinai
New York, New York, United States
Kris Foley, MD
Mount Sinai Hospital
New York, New York, United States
Intrathecal baclofen hypersensitivity post pump exchange
Case Description:
A 54-year-old woman with secondary progressive multiple sclerosis and spastic paraparesis underwent intrathecal baclofen (ITB) pump placement in 2018 after limited benefit from oral medications and botulinum toxin. Her ITB dose was titrated from 12 mcg/day to 30 mcg/day by discharge from inpatient rehabilitation. Outpatient, ITB was gradually increased to 85 mcg/day by late 2020, which controlled symptoms for one year. By 2022, spasticity worsened, with MRI demonstrating disease progression with increased cervical and thoracic spinal cord lesions. Dose requirements rose to 140 mcg/day by November 2024, without other identifiable triggers. In January 2025, the pump was replaced at the end of battery life. Postoperatively, baclofen was restarted at 80 mcg/day, leading to immediate hypotonia of the lower extremities. MRI was unremarkable for acute pathology. The ITB dose was tapered to 25 mcg/day, providing adequate spasticity control without functional weakness. Several months later, she remains stable on this dose.
Discussions:
This case highlights unexpected hypersensitivity to ITB following pump exchange. Prior to replacement, she required progressively higher doses for spasticity management, thought to reflect disease progression. The abrupt hypotonia at a lower dose post-exchange suggests a secondary factor contributed to the earlier dose escalation. When patients experience gradual loss of ITB efficacy, mechanical factors should be considered, including catheter migration, kinking, disconnection, or partial occlusion. Other causes include pump malfunction, catheter-tip granuloma, or pharmacologic tolerance. In this patient, an underlying catheter issue likely impaired drug delivery, leading to higher dose requirements. After pump replacement, restoration of normal delivery unmasked relative baclofen sensitivity.
Conclusions: Intrathecal baclofen sensitivity following pump exchange is rare but clinically significant. Clinicians should maintain suspicion for delivery-related problems in patients requiring progressive ITB dose escalation.
