Abstracts

Rationale: Two-stage craniotomies for subdural grid and strip implantation is a common surgical tool in pediatric functional neurosurgery and is used to better localize ictal onset and cortical stimulation mapping for the eloquent function of motor, sensory, and language functions. A common complication of two-stage implantation surgeries includes a higher risk of cerebral spinal fluid leak and infection due to prolonged periods of implantation of hardware. Two methods for performing two-stage implantations include free flap and osteoplastic craniotomies. It is suggested that the latter method retains bone viability due to the attachment of muscular blood supply, which is believed to reduce the risk of infection. However, there remains clinical equipoise regarding the optimal surgical technique for two-stage implants. We aimed to interrogate our institutional database to compare the postoperative performance of osteoplastic flap versus free flap in this setting.


Methods: A single-institution, retrospective chart review was performed using patient data ranging from September 2000 to February 2024 at Nicklaus Children’s Hospital (NCH), Miami, FL. Multiple variables were analyzed (craniotomy procedure, date of surgery, gender, age of seizure onset, complication type, presence of infection, and loss of bone flap due to infection). Using a Chi-Square test of independence (χ2), the relationship between craniotomy type, presence of infection, and bone flap loss was investigated.


Results: Two hundred eighty-four, two-stage subdural electrode procedures were recorded (30.28% free flap, 69.72% osteoplastic). There was no significance between craniotomy method (Free Flap versus Osteoplastic Bone Flap) on infection rate, χ2 (N = 286) = 2.109, p = 0.146. This suggests no difference in infection rate between free flap (2 out of 86 had infections) versus osteoplastic (13 out of 200 had infection). Bone flap viability is a major concern regarding patients with an infection. There was a difference between bone flap loss and craniotomy type (Free Flap versus Osteoplastic Bone Flap) among the patients who had an infection. We performed a Chi-Square test of independence that illustrated that the test was significant χ2 (N = 15) = 9.231, p = 0.002. There was a higher rate of bone flap loss in patients with infections who received a free flap craniotomy (2 out of 2 patients) compared to those who received an osteoplastic (1 out of 13 patients).


Conclusions: The results of this study illustrate that the use of an osteoplastic craniotomy for two-step subdural implantation retains bone viability, thus resulting in a lower rate of bone flap loss post-surgery. Although there was no significance between infection rate and craniotomy type, patients with an osteoplastic craniotomy underwent less invasive techniques to clear the infection (washout, drainage, intravenous antibiotics), which can aid in patient recovery. Understanding the association between surgical methods and infection/bone loss rates is critical for pre-surgical decision-making and overall patient recovery after surgical intervention.


Funding: N/A