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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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Chris Xenos, Spiros Sgouros, Kalyan Natarajan, A. Richard Walsh and Anthony Hockley

Object. The goal of this study was twofold: to investigate the change in ventricular volume in children with hydrocephalus in response to shunt placement and to assess the effects of two different valve types (Medium Pressure [MP] cylindrical valve and Delta [model 1.5] valve).

Methods. Ventricular volume was measured using segmentation techniques on computerized tomography scans and magnetic resonance images obtained in 40 children with hydrocephalus who ranged in age from 4 days to 16 years. Imaging was performed preoperatively and at 5 days and 3, 6, and 12 months postoperatively. The results were compared with measurements obtained in 71 healthy children ranging in age from 1 month to 15 years. Each ventricular volume that was measured was divided by the corresponding sex and age—related mean normal volume to calculate the “× normal” ventricular volume, indicating how many times larger than normal the ventricle was.

The mean preoperative ventricular volume was 232 cm3 (range 50–992 cm3). The mean postoperative volumes were 147, 102, 68, and 61 cm3 at 5 days and at 3, 6, and 12 months posttreatment, respectively. The mean preoperative × normal ventricular volume was 14.5 (range 2.2–141.7), and the mean postoperative × normal volumes were 7.9, 5.6, 3.5, and 2.9 at 5 days and 3, 6, and 12 months postimplantation, respectively. The rate of volume reduction was consistently higher in patients who received the MP valve in comparison with those who received the Delta valve, both for new shunt insertions and for shunt revisions. The difference between the two valve groups did not reach statistical significance. Two patients in whom ventricular volumes increased during the study period experienced shunt obstruction at a later time.

Conclusions. Preoperative ventricular volume in children with hydrocephalus can be up to 14 times greater than normal. In response to shunt placement, the ventricular volume continues to fall during the first 6 months after operation. The effect is more profound in children who receive the MP valve than in those who receive the Delta valve, although in this study the authors did not demonstrate statistical significance in the difference between the two valves. Nevertheless, this may indicate that the MP valve produces overdrainage in comparison with the Delta valve, even within the first few months after insertion. There is some indication that sequential ventricular volume measurement may be used to identify impending shunt failure.

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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.