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Adikarige H. D. Silva, William B. Lo, Nilesh R. Mundil, and A. Richard Walsh

The surgical approach to hypothalamic hamartomas (HHs) associated with medically refractory epilepsy is challenging because of these lesions’ deep midline or paramedian location. Whether the aim is resection or disconnection, the surgical corridor dictates how complete a procedure can be achieved. Here, the authors report a transtemporal approach suitable for Delalande type I, inferior extraventricular component of type III, and type IV lesions. This approach provides optimal visualization of the plane between the hamartoma and the hypothalamus with no manipulation to the pituitary stalk and brainstem, allowing for extensive disconnection while minimizing injury to adjacent neurovascular structures.

Through a 1-cm corticectomy in the middle temporal gyrus, a surgical tract is developed under neuronavigational guidance toward the plane of intended disconnection. On reaching the mesial temporal pia-arachnoid margin, it is opened, providing direct visualization of the hamartoma, which is then disconnected or resected as indicated. Critical neurovascular structures are generally not exposed through this approach and are preserved if encountered.

Three patients (mean age 4.9 years) with intractable epilepsy were treated using this technique as part of the national Children’s Epilepsy Surgery Service. Following resection, the patient in case 1 (Delalande type I) is seizure free off medication at 3 years’ follow-up (Engel class IA). The patient in case 2 (Delalande type III) initially underwent partial disconnection through a transcallosal interforniceal approach and at first had significant seizure improvement before the seizures worsened in frequency and type. Complete disconnection of the residual lesion was achieved using the transtemporal approach, rendering this patient seizure free off medication at 14 months postsurgery (Engel class IA). The patient in case 3 (Delalande type IV) underwent incomplete disconnection with a substantial reduction in seizure frequency at 3 years’ follow-up (Engel class IIIC). There were no surgical complications in any of the cases.

The transtemporal approach is a safe and effective alternative to more conventional surgical approaches in managing HHs with intractable epilepsy.

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William B. Lo, Mitul Patel, Guirish A. Solanki, and Anthony Richard Walsh

Gemella haemolysans has long been considered a commensal in the human upper respiratory tract. Commensals are natural inhabitants on or within another organism, deriving benefit without harming or benefiting the host. Opportunistic infection of the CNS by the species is exceedingly rare. In the present case, a 16-year-old boy was admitted with a ventriculoperitoneal shunt infection, which was confirmed to be due to G. haemolysans. Following antibiotic treatment, removal of the old shunt, and delayed insertion of a new shunt, the patient made a full neurological recovery. To the authors' knowledge, this is the eighth case of CNS infection with G. haemolysans. Although prosthesis-related infections have been reported in other systems, this is the first case of CNS infection by the bacterium associated with an implant. Previous reported cases of CNS infection by G. haemolysans are reviewed. Due to the variable Gram staining property of the organism, the difficulty in diagnosing G. haemolysans infection is emphasized.

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William B. Lo, Kyaw Z. Thant, Jameel Kaderbhai, Nicholas White, Hiroshi Nishikawa, Michael Stephen Dover, Martin Evans, and Desiderio Rodrigues

OBJECTIVE

Children with syndromic, multisuture, and lambdoid craniosynostosis undergoing calvarial surgery often have Chiari malformation type I (CM-I) (or cerebellar tonsillar herniation). The optimal management of this patient group, including the surgical techniques and timing of surgery, remains uncertain. Posterior calvarial distraction (PCD) is an effective method to increase the supratentorial cranial volume and improve raised intracranial pressure in children with complex craniosynostosis. This study investigated the efficacy of PCD in posterior fossa (PF) volume expansion and treatment of CM-I and associated syringomyelia (syrinx) in this group of children.

METHODS

This retrospective study included patients who were surgically treated between 2006 and 2015. Over 10 years, 16 patients with multisuture synostosis, lambdoid synostosis, or craniosynostosis associated with a confirmed genetic syndrome, and a concurrent CM-I, were included. The mean age at the time of surgery was 5.1 years (range 8 months–18 years). Fourteen patients had pansynostosis and 2 had lambdoid synostosis. Eight had a confirmed syndromic diagnosis (Crouzon in 8, Apert in 4, Pfeiffer in 1, and Saethre-Chotzen in 1). Ten patients had raised intracranial pressure; 4 had syringomyelia.

RESULTS

The average clinical follow-up was 50 months (range 9–116 months). Clinically, 9 patients improved, 7 remained stable, and none deteriorated. The average distraction distance was 23 mm (range 16–28 mm). The PF anterior-posterior (AP) distance/width ratio increased from 0.73 to 0.80 mm (p = 0.0004). Although an osteotomy extending inferior to the torcula (compared with superior) was associated with a larger absolute PF AP distance increase (13 vs 6 mm, p = 0.028), such a difference was not demonstrable when the PF AP distance/width ratio was calculated. Overall, the mean tonsillar herniation improved from 9.3 to 6.0 mm (p = 0.011). Syrinx dimensions also improved in the AP (from 7.9 to 3.1 mm) and superior-inferior (from 203 to 136 mm) dimensions. No patients required further foramen magnum decompression for CM. Of the 16 patients, 2 had subsequent frontoorbital advancement and remodeling, of which 1 was for volume expansion and 1 was for cosmetic purposes. Two patients required CSF shunt insertion after PCD.

CONCLUSIONS

Following PCD, PF volume increased as well as supratentorial volume. This morphometric change was observed in osteotomies both inferior and superior to the torcula. The PF volume increase resulted in improvement of cerebellar tonsillar herniation and syrinx. PCD is an efficacious first-line, single-stage treatment for concurrent pansynostosis and lambdoid craniosynostosis, CM-I, and syrinx.

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Ioannis N. Mavridis, William B. Lo, Welege Samantha Buddhika Wimalachandra, Sunny Philip, Shakti Agrawal, Caroline Scott, Darren Martin-Lamb, Bryony Carr, Peter Bill, Andrew Lawley, Stefano Seri, and A. Richard Walsh

OBJECTIVE

The safety of stereo-electroencephalography (SEEG) has been investigated; however, most studies have not differentiated pediatric and adult populations, which have different anatomy and physiology. The purpose of this study was to assess SEEG safety in the pediatric setting, focusing on surgical complications and the identification of patient and surgical risk factors, if any. The authors also aimed to determine whether robot assistance in SEEG was associated with a change in practice, surgical parameters, and clinical outcomes.

METHODS

The authors retrospectively studied all SEEG cases performed in their department from December 2014 to March 2020. They analyzed both demographic and surgical variables and noted the types of surgery-related complications and their management. They also studied the clinical outcomes of a subset of the patients in relation to robot-assisted and non–robot-assisted SEEG.

RESULTS

Sixty-three children had undergone 64 SEEG procedures. Girls were on average 3 years younger than the boys (mean age 11.1 vs 14.1 years, p < 0.01). The overall complication rate was 6.3%, and the complication rate for patients with left-sided electrodes was higher than that for patients with right-sided electrodes (11.1% vs 3.3%), although the difference between the two groups was not statistically significant. The duration of recording was positively correlated to the number of implanted electrodes (r = 0.296, p < 0.05). Robot assistance was associated with a higher number of implanted electrodes (mean 12.6 vs 7.6 electrodes, p < 0.0001). Robot-assisted implantations were more accurate, with a mean error of 1.51 mm at the target compared to 2.98 mm in nonrobot implantations (p < 0.001). Clinical outcomes were assessed in the first 32 patients treated (16 in the nonrobot group and 16 in the robot group), 23 of whom proceeded to further resective surgery. The children who had undergone robot-assisted SEEG had better eventual seizure control following subsequent epilepsy surgery. Of the children who had undergone resective epilepsy surgery, 42% (5/12) in the nonrobot group and 82% (9/11) in the robot group obtained an Engel class IA outcome at 1 year (χ2 = 3.885, p = 0.049). Based on Kaplan-Meier survival analysis, the robot group had a higher seizure-free rate than the nonrobot group at 30 months postoperation (7/11 vs 2/12, p = 0.063). Two complications, whose causes were attributed to the implantation and head-bandaging steps, required surgical intervention. All complications were either transient or reversible.

CONCLUSIONS

This is the largest single-center, exclusively pediatric SEEG series that includes robot assistance so far. SEEG complications are uncommon and usually transient or treatable. Robot assistance enabled implantation of more electrodes and improved epilepsy surgery outcomes, as compared to those in the non–robot-assisted cases.