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J Neurosurg Case Lessons
J Neurosurg Case Lessons
J Neurosurg Case Lessons
Journal of Neurosurgery: Case Lessons
2694-1902
American Association of Neurological Surgeons

39222544
10.3171/CASE24290
CASE24290
Functional-NeurosurgeryFunctional NeurosurgeryPainPainPediatricPediatricSpineSpinePediatric-SpinePediatric SpineTechniqueTechniqueSurgical-TechniqueSurgical TechniqueCase Lesson
Peritoneal baclofen pump migration: a rare complication of subfascial placement. Illustrative cases
Ricciardelli Ashley BA 12
Guntin Jordan MD 12
Korb Joshua BS 12
Curry Daniel J MD 12
Gadgil Nisha MD 12
1 Division of Neurosurgery, Department of Surgery, Baylor College of Medicine, Houston, Texas
2 Division of Neurosurgery, Department of Surgery, Texas Children’s Hospital, Houston, Texas
Correspondence Nisha Gadgil: Texas Children’s Hospital, Houston, TX. nxgadgil@texaschildrens.org.
INCLUDE WHEN CITING Published September 2, 2024; DOI: 10.3171/CASE24290.

Disclosures The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.

02 9 2024
02 9 2024
8 10 CASE2429003 5 2024
10 7 2024
© 2024 the authors
2024
the authors
https://creativecommons.org/licenses/by-nc-nd/4.0/ CC BY-NC-ND 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/)

BACKGROUND

The intrathecal baclofen pump is an effective treatment option for patients with severe spasticity. In children, subfascial pump placement is often preferred given concerns for infection and wound healing. However, this approach is not without risk, and rare complications, such as peritoneal pump migration, can occur.

OBSERVATIONS

The authors describe three pediatric cases of peritoneal pump migration at their institution over the past 14 years (3/545, 0.5%). All three patients had low body weight (below the 39th percentile), and two had scoliosis requiring surgery. All pumps had been placed using the subfascial technique. The first case occurred 6 months postplacement, and the pump was not replaced. Cases 2 and 3 occurred at 2 and 3 years postplacement, respectively, and both pumps were replaced.

LESSONS

The authors conclude that peritoneal pump migration, although uncommon, can occur in patients with subfascial pump placement, and providers should have a low threshold of suspicion for repeat imaging prior to refilling if the pump’s location has migrated. Potential contributing factors to pump migration include a patient’s small size, a larger pump size (40-mL pump), and scoliosis. All these factors should be considered during pump placement, and surgeons can consider using a 20-ml pump for smaller patients.

https://thejns.org/doi/abs/10.3171/CASE24290

case series
baclofen pump
complication
peritoneal migration
ABBREVIATIONS

BMI = body mass index
CT = computed tomography
IBP = intrathecal baclofen pump.
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pmcIntrathecal baclofen pumps (IBPs) are implantable devices used to treat spasticity and dystonia related to underlying neurological disorders such as cerebral palsy, multiple sclerosis, and traumatic brain and spinal cord injuries.1 While effective, baclofen pumps have notoriously high complication rates. In a retrospective review of 200 cases of IBP implantation in children, Motta et al.2 reported a 31% complication rate. The most common complications included cerebrospinal fluid leakage (11%), catheter-related problems (7%), and infection (7.5%), with 5.5% of patients experiencing more than one of these complications. In a 20-year retrospective cohort study of 130 pediatric patients, Bonouvrié et al.3 reported a similarly high complication rate (36.2%), of which the majority were catheter-related problems (55.7%), followed by infections (21.6%), cerebrospinal fluid leakage (14.8%), and pump complications (7.9%). Potential risk factors for these complications include low body mass index (BMI), younger age at implantation, male gender, nonambulatory status, number of years since pump placement, presence of gastrostomy tube, and catheter type,3, 4 with Motta et al.2 finding a statistically significant correlation between complication rate and an Ashworth score > 3 and age < 10 years. Other single-institution studies have confirmed high complication rates ranging from 26.6% to 37.5%.1, 5

Baclofen pumps can be implanted in the subfascial or subcutaneous layer of the abdomen.6 In the subfascial technique, a subcostal incision is created, the rectus abdominis fascia is incised, and a subfascial pocket is dissected to allow for a tensionless insertion of the pump. The pump is situated underneath the rectus sheath medially and the external oblique muscle laterally and is located anterior to the rectus abdominis, internal oblique, and transversus abdominis muscles, as well as the peritoneum.6 In contrast, the subcutaneous approach involves creating a pocket in the subcutaneous layer of the abdominal wall, anterior to the rectus sheath and abdominal musculature.6

Subfascial pump implantation is common practice in the pediatric population, as it offers several advantages, including greater soft tissue coverage, improved cosmetic appearance, and a reduced risk of skin breakdown.2 Peritoneal pump migration is an uncommon but potentially life-threatening complication that should be recognized in patients with subfascial baclofen pumps. To date, there have been a total of two cases reported in the literature, neither of which involved children.7, 8

In this report, we describe three pediatric patients with this complication over the past 20 years at a high-volume institution.

Illustrative Cases

Case 1

A 5-year-old boy weighing 20.1 kg (BMI 20.4) with hypomyelinating leukodystrophy resulting in generalized spasticity underwent uneventful subfascial pump placement with a 40-mL Medtronic SynchroMed II IBP. Four weeks after pump placement, he experienced severe abdominal pain, prompting an urgent care visit. Radiography was not performed at that time, and the pain subsided within a few weeks.

Six months later, the patient presented for a routine pump refill and was noted to have displacement of his baclofen pump to the contralateral side. Computed tomography (CT) imaging showed intraperitoneal pump migration, with no free air or apparent viscus injury (Fig. 1). He underwent exploration through the prior right-sided subcostal incision. After opening the skin and superficial rectus fascia, nonoverlapping defects in the rectus muscle and posterior fascia were noted, suggestive of erosion of the pump through these layers. Herniation of omentum and bowel contents was seen through the abdominal musculature through a ventral hernia in the posterior rectus fascia. The intrathecal catheter remained intact and was traced through the defect in the posterior fascia, and the pump was removed. Abdominal contents were inspected, and no intra-abdominal or viscus injury was noted. The ventral abdominal hernia was repaired primarily. The pump and intrathecal catheter were removed. No fever, drainage, or swelling was noted on follow-up after the procedure, and the patient recovered uneventfully. The patient’s caregivers elected not to proceed with pump replacement. FIG. 1. Case 1. A:TheIBP postoperatively, placed in the right lower abdomen. B: Radiograph obtained approximately 6 months after placement, showing the pump located in the left abdomen. C: View showing lateral displacement of the pump in the left abdomen. D: CT confirming intraperitoneal pump migration.

Case 2

A 5-year-old female weighing 18.1 kg (BMI 15.8) with spastic quadriparesis and scoliosis, specifically dextroconvex curvature of the thoracolumbar spine (requiring surgery later on at age 12 years), underwent subfascial baclofen pump placement with a 20-mL SynchroMed II pump. Two years later, she presented with abdominal pain and emesis, and the pump was found to have migrated inferiorly toward the pelvis. Radiographs confirmed intraperitoneal migration of the pump. The previous subcostal incision was reopened, and a fascial defect was identified. The baclofen pump was subsequently retrieved. After the fascial defect was repaired, a new subcutaneous pocket was created, and the same 20-mL pump was replaced within this pocket. No further wound complications occurred. The pump was electively replaced 4 years later for end of battery life and was explanted 2 months later for infection.

Case 3

An 8-year-old male weighing 18.8 kg with spastic quadriplegia related to cerebral palsy and dextroconvex thoracolumbar scoliosis (later requiring surgical correction at the age of 17 years) underwent uneventful subfascial placement of a 20-mL SynchroMed EL baclofen pump. The patient underwent replacement of only the catheter 1 year later for suspected malfunction. Three years after the initial pump placement, there was again concern for pump malfunction, and the patient was taken to the operating room for exploration. Deep to the subfascial pocket, a ventral wall hernia was noted beneath the pump. The hernia was repaired by a pediatric surgeon, and a new 20-mL SynchroMed II pump was implanted within the same subfascial pocket. One year later, the patient presented with severe skin erosion overlying the abdominal pump site for which he underwent removal of the entire system, with no fascial defect noted at the time of surgery.

Patient Informed Consent

The necessary parental informed consent was obtained in this study.

Discussion

Observations

Intraperitoneal migration of an IBP is a rare but serious complication of subfascial pump placement, particularly if the intraperitoneal migration is not observed and a pump refill is attempted. The first reported case of pump migration was discovered in a 54-year-old patient during exploratory surgery after an inability to refill the pump. Prior to this incident, the pump, which had been placed using the subfascial technique, was successfully refilled 10 times. The authors proposed several potential explanations for this erosion, including chronic pressure of the pump against the inner fascia and muscles from the continuous tone of the muscular abdominal wall and muscle necrosis and atrophy from coagulation and hemostasis. In this patient, the pump incision had been made 10 cm below the ribs, below the linea semilunaris, where the abdominal musculature posterior to the pump is less robust and potentially provides less support.8

The second reported case of IBP migration occurred in a 26-year-old male with cerebral palsy who had undergone subfascial placement 20 years prior with two replacements. Discovery of the migration occurred when providers were unable to palpate the pump for a refill. The 40-mL pump was retrieved and replaced with a 20-mL pump, which was positioned subcutaneously.7

In children, there are particular concerns regarding wound healing following IBP placement. Children with cerebral palsy and movement disorders are commonly underweight, in part related to high energy expenditure, and lack substantial subcutaneous tissue, with studies showing significantly lower body weight (64% of the median) and fat stores (61%–81% of the median).9 Subfascial placement is often preferred for this reason. A small patient size and pump size are important factors to consider, as a larger pump size can increase the chance of wound complications. In this case series, all patients weighed 20 kg or less at the time of pump placement (Table 1). Albright et al. suggested that larger pumps can be inserted in nearly all children weighing over 18.1 kg without undue tension and that smaller pumps need to be inserted in all patients weighing less than 13.6 kg.10 Though this was prior to the introduction of the SynchroMed II model, the dimensions of the available pump at the time (SynchroMed EL 18 mL) were similar. The 40-mL pump size was placed in the patient in case 1, who weighed 20.1 kg; however, his overall habitus, with a height below the 1st percentile, may have contributed to tension and erosion. TABLE 1. All cases of subfascial IBP peritoneal migration at our institution during 14 years

Case No.	Gender	Diagnosis	GMF-CS Grade	Age at Placement (yrs)	Height in cm (percentile)	Weight in kg (percentile)	BMI in kg/m2 (percentile)	Pump Size (mL)	Scoliosis	
1	M	Leukodystrophy, spastic quadraplegia	V	5	98.8 (<1%)	20.1 (39%)	20.4 (98%)	40	No	
2	F	Cerebral palsy, spastic quadraplegia	V	5	107 (42%)	18.1 (32%)	15.8 (66%)	20	Yes	
3	M	Cerebral palsy, spastic quadraplegia	V	8	Not available	18.8 (<3%)	Not available	20	Yes	
GMF-CS = gross motor function classification system.

GMF-CS V indicates that children are transported in a manual wheelchair in all settings, have limited antigravity head and trunk posture, and have limited control over their limbs.

It is possible that deformity related to neuromuscular scoliosis can increase the risk of intraperitoneal migration. Severe scoliosis requiring surgical correction at a later age was noted in two of the three patients in our case series. We speculate that increased pressure on the pump related to scoliotic deformity may have contributed to pressure on the baclofen pump, ischemia of the abdominal musculature posteriorly, and eventual fascial dehiscence. Hyperlordosis, in particular, is a challenging deformity that may have contributed to pump migration and malfunction given excessive anterior curvature.

Reflecting on IBP migration, we hypothesize that a patient’s small size (20 kg or less), larger pump size, and scoliosis can be potential contributing factors. Prior to subfascial pump placement, we recommend a close inspection of the posterior pocket to ensure there are no areas of defect or weakness. If such areas are found, they should be repaired and reinforced. During pump placement, we recommend exercising caution when placing a larger pump size in smaller children and performing careful dissection to achieve tensionless closure of the subfascial pocket. Importantly, both neurosurgeons and physical medicine and rehabilitation specialists, as well as any providers involved in pump refills, should be acquainted with this rare complication, which can occur even years after the initial pump placement. Any discrepancies in pump location should be further investigated with imaging prior to pump refill. Unexplained abdominal pain in a patient with a baclofen pump can also warrant imaging. In the cases reported, recognition of the complication avoided potentially serious complications such as bowel injury. If this complication is identified, revision surgery should be performed with a general surgeon. The bowel should be carefully inspected for any evidence of injury, and fascial defects should be carefully repaired in layers. The pump can be explanted or replaced simultaneously within a new pocket, either subfascial or subcutaneous. In the absence of viscus injury, the pump can be safely reimplanted, as seen in cases 2 and 3.

Lessons

To conclude, IBP migration, although uncommon, can occur in patients with subfascial pump placement. Providers should pursue imaging to evaluate for this complication prior to pump refill if the patient presents with pump location discrepancy and new symptomatology. Furthermore, we suggest that small habitus, pump size, and scoliosis can contribute to pump migration and recommend that surgeons consider using a 20-mL pump for smaller patients.

Disclosures

The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.

Author Contributions

Conception and design: Gadgil, Guntin, Curry. Acquisition of data: Ricciardelli, Guntin, Korb, Curry. Analysis and interpretation of data: all authors. Drafting the article: Ricciardelli, Guntin, Korb. Critically revising the article: all authors. Reviewed submitted version of manuscript: all authors. Approved the final version of the manuscript on behalf of all authors: Gadgil. Statistical analysis: Guntin. Administrative/technical/material support: Guntin. Study supervision: Gadgil, Guntin.

Correspondence

Nisha Gadgil: Texas Children’s Hospital, Houston, TX. nxgadgil@texaschildrens.org.
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