Combined intrathecal baclofen pump revision to the cervical level and lumbosacral ventral-dorsal rhizotomy for severe medically refractory hypertonia: illustrative cases

Abstract

BACKGROUND

Medically refractory hypertonia (MRH) within the pediatric population causes severe disability and is difficult to treat. Neurosurgery for mixed MRH includes intrathecal baclofen (ITB) and lumbosacral ventral-dorsal rhizotomy (VDR). Surgical efficacy limitations can be mitigated by combining the two into a multimodal strategy. The authors examined outcomes following a multimodal neurosurgical strategy combining intraspinal ITB catheter revision to the cervical level and lumbosacral VDR.

OBSERVATIONS

Two patients with severe MRH resistant to ITB delivered through a thoracic catheter tip were identified: 1) a 16-year-old boy with quadriplegic mixed hypertonia and 2) a 17-year-old girl with secondary dystonia. The patient in case 1 experienced improvement in his Barry-Albright Dystonia Scale (BADS) score from 29 to 17 and lower-extremity modified Ashworth Scale score from 4 to 0 at 18 months postoperatively; the patient in case 2 experienced a decrease in her BADS score from 30 to 13 at 6 months postoperatively. Significant improvement in caregiving provisions, including patient positioning and transfers, was reported.

LESSONS

The authors highlight favorable outcomes using multimodal surgery in pediatric patients. Multimodal therapy is surgically feasible and better addresses MRH, particularly in patients in whom ITB monotherapy and polypharmacy have failed. Future studies with larger patient volumes are necessary to optimize indications and make more definitive outcome conclusions.

https://thejns.org/doi/10.3171/CASE24599

Hypertonia significantly affects functional status and quality of life.¹ Cerebral palsy (CP), the most common cause of hypertonia, affects 2.11 per 1000 live births globally.^2–4 Treatment options for hypertonia include medical management and physical interventions (e.g., bracing), whereas medically refractory hypertonia (MRH) often necessitates surgical intervention.⁵ The traditional neurosurgical management of pediatric hypertonia includes selective dorsal rhizotomy (SDR), intrathecal baclofen (ITB), and deep brain stimulation (DBS).⁶ SDR is used as a treatment for spastic diplegia to reduce tone and improve ambulatory function; however, SDR is controversial in children with mixed hypertonia or secondary dystonia due to the potential to exacerbate the dystonic component.^7,8 In contrast, studies have demonstrated combined ventral-dorsal rhizotomy (VDR) to be an effective alternative in patients with mixed hypertonia or dystonia, resulting in improved patient comfort, function, and transfers.^9–11 Despite the demonstrated safety and efficacy of VDR and ITB for children with MRH individually, there remains a paucity of studies discussing multimodal therapy for hypertonia.

Both ITB and lumbosacral VDR have limitations. Following ITB pump (ITBP) implantation, 8% of patients experienced a recurrence of hypertonia, whereas approximately 16% of patients with lumbosacral VDR did not experience the expected tone reduction.^11,12 A nonoptimal response to one treatment modality might not predict the response to additional, alternative therapies; SDR has been used effectively to treat spasticity in pediatric patients with CP who have previously underresponded to ITB therapy.¹³ Patients with quadriplegic mixed hypertonia or dystonia receiving ITB can experience residual hypertonia, particularly in their upper extremities due to proximity-dependent baclofen distribution.^12,14,15 Multimodal therapy has the potential to address MRH that is not effectively managed with a single neurosurgical modality. We report two cases in which pediatric patients underwent both intraspinal ITB catheter revision from a thoracic to a cervical tip and lumbosacral VDR to treat refractory hypertonia.

Illustrative Cases

A retrospective chart review was conducted of patients at our institution who had undergone concurrent intraspinal ITBP conversion from a thoracic to a cervical catheter tip placement and lumbosacral VDR to treat MRH between 2021 and 2023. We collected and reviewed patient demographics, operative characteristics, and surgical outcomes. Licensed physiatrists measured tone control using the modified Ashworth Scale (mAS) and Barry-Albright Dystonia Scale (BADS) pre- and postoperatively. All necessary data are reported in the article.

Surgical Technique

After appropriate antibiosis, the patients were positioned supine under general anesthesia. A 25-gauge noncoring needle was introduced into the pump side port and used to aspirate 2 ml of spinal fluid to clear the catheter. Then the patients were positioned prone. The intrathecal catheter incision in the patients’ backs was reopened, and the components of the spinal segment, colette, and anchor were identified. The anchor was freed, and the previous catheter was removed and discarded, leaving a small segment of catheter available for connection to the new spinal segment. A 14-gauge Tuohy needle was used to gain access to the lumbar cistern, and the flow of cerebrospinal fluid confirmed correct positioning. The new catheter was placed through the Tuohy needle to the C2–3 space using fluoroscopy, and the needle was removed and subsequently secured to the fascia. It was connected to the remaining segment of the spinal catheter heading to the pump pocket to constitute a patent catheter system. Diluted betadine and vancomycin were used for irrigation, followed by placement of intrawound vancomycin powder. The wound was closed in a typical layered fashion.

Following completion of the intraspinal ITBP conversion to a cervical catheter tip and closure, gloves were changed. A nonselective bilateral L1–S1 VDR was performed through a T12–L2 laminoplasty, as previously described.¹⁰ Triggered electromyography confirmed the identity of the nerve roots before sectioning 80%–90%. After completion, the patients were returned to the supine position, and the catheter was cleared once more through side port aspiration. Postoperative programming included a catheter bolus filling the catheter plus an additional 50-µg bolus. Patients were admitted for observation and management of baclofen dosing by our pediatric physiatrists prior to discharge.

Case 1

A 16-year-old boy with quadriplegic mixed hypertonia CP secondary to intraventricular hemorrhage (Gross Motor Function Classification System [GMFCS] level V) was evaluated by the Shirley Ryan Ability Lab–Lurie Children’s Hospital Complex Movement Disorder Program. Previously, the patient had trialed multiple medical therapies (clonidine, diazepam, trihexyphenidyl, pregabalin), received botulinum toxin (Botox) injections, underwent multiple orthopedic procedures, and had an ITBP with the tip placed at L2 with flex-dosing totaling of 1015 µg/day without adequate tone control. Hypertonia of the lower extremities was worsening, causing significant pain and discomfort. The patient also experienced exacerbations of his oropharyngeal dystonia that led to aspiration pneumonitis. His physical examination was significant for severe mouth dystonia with constant open positioning and mixed spastic, dystonic quadriplegic hypertonia causing contraction in all extremities with a limited range of motion at his elbows and knees bilaterally. He had a preoperative BADS score of 29 (lower extremity = 8), a bilateral upper-extremity mAS score of 2, and a bilateral lower-extremity score of 4. We recommended a combined intraspinal revision of his baclofen catheter to C2–3 to better manage his oropharyngeal and upper-extremity hypertonia and a bilateral lumbosacral VDR to address his lower-extremity tone.

The operative time was 278 minutes, with an estimated blood loss of 50 ml. We continued his 1015 µg/day flex-dosing regimen. Postoperatively, the patient experienced a pseudomonas infection and wound dehiscence at the rhizotomy site, requiring wound revision and subsequent removal of the laminoplasty set and devitalized lamina. There were no complications with the intraspinal ITBP catheter revision.

The patient was weaned off enteral baclofen at the 3-month follow-up. His BADS score improved from 29 to 17 (lower extremity = 2), his lower-extremity mAS score improved from 4 to 0, and his upper-extremity mAS score was 1 (Table 1). The family reported satisfaction with the outcomes, and significant improvements in the provisions of caregiving were reported, including dressing, changing, positioning, and transfers. The patient had lasting improvement in tone at 18 months of follow-up.

TABLE 1.

Measures of tone control

	Preop	Postop
Case 1
UE mAS score	2	1
LE mAS score	4	0
BADS score	29	17
LE BADS score	8	2
Case 2
BADS score	30	13
LE BADS score	8	0

LE = lower extremity; UE = upper extremity.

Case 2

A 17-year-old girl with generalized secondary dystonia CP (GMFCS level V) was evaluated by the Marionjoy Rehabiliation Hospital–Lurie Children’s Hospital Complex Movement Disorder Program. The patient had previously undergone bilateral globus pallidus internus DBS as well as a mid-thoracic ITBP placement with the tip at T6 on continuous dosing of 2399 µg/day in an attempt to control her dystonia. Despite multiple pump adjustments, high baclofen dosing, Botox injections, and numerous medications (carbidopa/levodopa, diazepam, clonazepam, propranolol, clonidine, duloxetine, hydroxyzine, and gabapentin), the patient’s tone worsened. She presented with recurrent episodes of status dystonicus and severe contractures in both the upper and lower extremities. Preoperatively, the patient had a BADS score of 30 (lower extremity = 8). On physical examination, she exhibited rigidity in all four extremities. The consensus opinion was to convert her intraspinal catheter to C2 for more effective management of her upper-extremity tone and a bilateral lumbosacral VDR for her lower extremity symptoms.

The operative duration was 362 minutes, with an estimated blood loss of 30 ml. We continued her simple continuous dosing of baclofen of 2399 µg/day. She was transferred to the pediatric intensive care unit for observation and experienced a significant reduction in tone throughout. On postoperative day (POD) 2, she began exhibiting respiratory distress, lethargy, vertical nystagmus, and dysphagia requiring nasogastric tube placement. These symptoms were attributed to baclofen toxicity, necessitating an incremental dose reduction of baclofen from 2399 µg/day to 1955 µg/day. Her symptoms improved, and she was discharged to inpatient rehabilitation on POD 14.

Her BADS score improved from 30 to 13 (lower extremity = 0) at 1 month of follow-up, and her caregivers reported improved positioning and transfers (Table 1). At 6 months postoperatively, the patient continued to exhibit improved tone and she was able to attend a full 5-day school week for the first time in many years.

Informed Consent

The necessary informed consent was obtained in this study.

Discussion

Hypertonia is a debilitating condition in the pediatric population that can cause pain and negatively affect bodily function, mobility, and quality of life. ITB is a reversible gamma-aminobutyric acid–B receptor agonist that has demonstrated safety and efficacy in controlling mixed MRH, while lumbosacral VDR is a permanent denervation procedure that has shown similar results.^{9–11,14,16–19}

Observations

In this series, two patients with CP (GMFCS level V) and MRH to both medical management and ITB therapy underwent an intraspinal ITBP conversion to cervical catheter tip placement and lumbosacral VDR. Both patients had previously undergone numerous procedures to address their hypertonia, including bilateral DBS, Botox injections, extensive antispasmodic polypharmacy, and ITBP placement with several adjustments to achieve high baclofen doses. Despite these attempts, adequate tone control was not achieved, and their quality of life was severely affected. These severe cases of hypertonia prompted a multimodal approach including ITBP revision and lumbosacral VDR to better control hypertonia. Both patients experienced favorable outcomes with an overall reduction in tone and improvement in caregiving provisions such as dressing, positioning, and transfers.

An intraspinal catheter revision to the cervical level was conducted to address the patients’ upper-extremity mixed hypertonia. While the ITB catheter tip target is often at the low- or midthoracic level, studies suggest that a cervical tip location better addresses mixed hypertonia and dystonia.^14,20 The origin of dystonia is hypothesized to be a pathology of cerebral dysregulation, and it is theorized that ITB efficacy can be increased with catheter tip placement closer to the brain or even within the ventricular system.¹⁴ Intraspinal cervical ITB catheter revision and lumbosacral VDR surgery were performed rather than cervical VDR and continued lumbar ITB to minimize the morbidity of cervical VDR and optimize generalized tone control via a higher ITB catheter tip. Intraventricular baclofen (IVB) is an alternative strategy with demonstrated safety and efficacy in the treatment of secondary dystonia, reducing mean BADS scores from 23 to 8; however, IVB requires cranial access, which would not have been possible through the same surgical positioning.^21–23

Considerations

Although the reported complications eventually resolved for both patients, it is important to understand the possible complications from these procedures. Postoperative wound infection is a serious complication that can be more prevalent in this at-risk population.

ITB can also result in complications associated with mechanical implant dysfunction or baclofen toxicity. Baclofen toxicity can result in severe symptoms, including hypotension, hypothermia, respiratory depression, dysphagia, seizure, and even death.²⁴ Thus, ITB therapy requires close monitoring and management before, during, and after the procedure to reduce the complications that can occur. The patient in case 2 experienced respiratory depression and dysphagia secondary to baclofen toxicity at a very high daily dose, which resolved following titration adjustment. There are no standard guidelines regarding dosing of baclofen after a catheter revision. Some clinicians choose to systematically reduce the catheter dosing for all patients, while others maintain the dosing and adjust symptomatically. Previous studies have found that patients undergoing a spinal catheter revision compared to a pump replacement had significantly lower baclofen dosing postoperatively.²⁵ However, these studies are in patients who required a catheter revision due to a nonfunctioning catheter; in our patients, the catheter was functional. While baclofen toxicity is an important consideration, reducing baclofen dosing too quickly can also lead to baclofen withdrawal, which is a potential consideration. In seven patients undergoing cervical catheter repositioning, only one patient developed baclofen toxicity, suggesting that there is no need to decrease the dosing in most cases.¹⁴ Further research is necessary to discern whether dose adjustments should be preemptive in patients with high preoperative baclofen dosing with thoracolumbar catheter tips who undergo intraspinal cervical catheter revision or if this was an anecdotal finding.

It is important to consider the potential coincident complications with a multimodal approach. Severe cases of MRH can justify the potential increased risk, though careful multidisciplinary consideration is necessary for optimal patient selection. Ideal patient selection would typically be patients with severe MRH in whom previous traditional thoracolumbar ITBP has failed and who continue to have generalized hypertonia of both upper and lower limbs. The severity of MRH is a more reliable marker of the utility of this approach rather than the etiology of hypertonia.

Repositioning the cervical catheter followed by lumbosacral VDR in a subsequent surgery was considered; however, this would not address the patient’s lower-extremity tone and would require an additional anesthesia experience and delay overall symptomatic improvement.

Limitations

Conclusions about the efficacy and safety of concurrent ITB and lumbosacral VDR are limited by our small sample size; as a result, the conclusions might not be generalizable. Although this approach appears effective in the short term, we have a limited long-term follow-up time of only 18 months; therefore, the long-term effects of this approach are unclear. Further research and longer follow-up times are necessary to determine the durability of this approach.

Lessons

MRH within the pediatric population leads to severe disability and can be difficult to treat. We highlight concurrent conversion to cervical ITB and lumbosacral VDR in pediatric patients reporting favorable outcomes. Multimodal therapy is feasible and addresses severe MRH in these patients. Further studies are necessary to optimize patient selection and outcomes.

Disclosures

Dr. Raskin reported personal fees from Synergia, Medtronic, BlackRock Neurotech, and Iota outside the submitted work.

Author Contributions

Conception and design: Raskin, Abdelmageed, Trierweiler. Acquisition of data: Raskin, Abdelmageed, Trierweiler, Keen, Katholi. Analysis and interpretation of data: Raskin, Abdelmageed, Bae, Trierweiler, Keen, Katholi. Drafting the article: Raskin, Abdelmageed, Bae, Mossner, Trierweiler. Critically revising the article: Raskin, Abdelmageed, Mossner, Katholi. Reviewed submitted version of manuscript: all authors. Approved the final version of the manuscript on behalf of all authors: Raskin. Administrative/technical/material support: Raskin, Trierweiler. Study supervision: Raskin.

Correspondence

Jeffrey S. Raskin: Ann & Robert H. Lurie Children’s Hospital, Northwestern University Feinberg School of Medicine, Chicago, IL. jraskin@luriechildrens.org.