New endoscopic route to the temporal horn of the lateral ventricle: surgical simulation and morphometric assessment

Object

The temporal horn of the lateral ventricle is a complex structure affected by specific pathological conditions. Current approaches to the temporal horn involve a certain amount of corticotomy and white matter disruption. Surgeons therefore set aside anterior temporal lobectomy as a last resource and avoid it in the dominant hemisphere. The authors propose a minimally invasive endoscopic intraventricular approach to the temporal horn and describe a standardized analysis and technical assessment of the feasibility of this approach.

Methods

To determine the best trajectory, angulation, and entry point to the temporal horn of the lateral ventricle, the authors evaluated 50 cranial MRI studies (100 temporal lobes) from healthy patients. They studied and systematized the neurosurgical endoscopic anatomy. They also simulated the proposed approach in 9 cadaveric specimens (18 approaches).

Results

Mean scalp entry point coordinates (± SD) were 2.7 ± 0.28 cm lateral to the inion and 5.6 ± 0.41 cm superior to the inion. The mean total distance from the uncal recess to the scalp (± SD) was 10.64 ± 0.6 cm. The mean total intraparenchymal distance crossed by the endoscope was 3.76 ± 0.36 cm. The approach was successfully completed in all studied specimens.

Conclusions

In this study, the endoscopic intraventricular approach to the temporal horn is standardized. The morphometric analysis makes this approach anatomically feasible and replicable. This approach provides minimally invasive endoscopic access to the uncal recess, amygdala, hippocampus, fornix, and paraventricular temporal lobe structures. The following essential strategies enabled access to and maneuverability inside the temporal horn: tailored preoperative planning of the trajectory and use of anatomical and radiological references, constant irrigation, and an angled endoscopic lens. Safety assessment and novel instruments and techniques may be proposed to advance this very promising route to pathological changes in the temporal lobe.

New stereoscopic virtual reality system application to cranial nerve microvascular decompression

PURPOSE

Cranial nerve microvascular decompression is a habitual neurosurgical procedure. Authors describe a new application of the Dextroscope (Volume Interactions, Ltd.), a virtual reality environment, to plan and properly simulate this kind of procedures.

METHODS

In three cases of hemifacial spasm refractory to drugs and botulinum toxin treatment, the authors used a virtual reality workstation (Dextroscope) to develop an interactive simulation of craniotomy, approach, and Gore-Tex implant optimal size and position in order to reach vascular decompression of facial nerve.

RESULTS

Three-dimensional interactive environment allowed the authors to virtually carry out craniotomy, to visualize vascular and nerve relationship, and finally, to select and to simulate best Gore-Tex graft positioning in each case. During surgical procedures, facial nerve vascular compressions were exposed and Gore-Tex grafts were successfully placed as it was virtually planned. Patient outcomes were excellent, with an average improvement of two units (0-4 grades of severity scale).

CONCLUSION

Virtual reality environment can help the neurosurgeon to plan and train vascular decompression procedures. Use of appropriate craniotomy, knowledge of vascular and nerve relationship, and selection of optimum paddy size and position are the main useful applications of the Dextroscope in these procedures.

[Prevalence of anti-mumps IgG antibodies in a pediatric population]

BACKGROUND

To assess the prevalence of IgG antibodies against mumps virus, using an enzyme-linked immune assay, among a pediatric population aged from 2 to 14 years.

METHOD

Using a systematic sampling technique among rural and urban pediatric population in a sanitary Spanish area (Leon, Spain) we enrolled 800 children in the study. In all cases the vaccination status, prior history of mumps and also data regarding the place where the vaccination took place were recorded. The presence or absence of IgG antibodies against mumps virus was determined using a standard commercially-available technique (EIA Stat IgG Mumps).

RESULTS

Of all children enrolled in the study, a 76.87% +/- 2.92% showed a positive antibody response against mumps virus. The percentage of susceptible children to mumps virus was therefore deemed to be 27.13% +/- 2.9%. A total of 100 children (25.8%) of all 387 who were previously vaccinated did not show presence of antibodies against mumps.

CONCLUSIONS

In our study, the immunity pattern did not showed statistical positive correlation with all variables assessed: sex, place where the vaccine was given, residence (rural/urban). The high rates of vaccination coverage achieved among children aged 2 to 14 had induced a major change in the immune status, a 71.20% of children had IgG antibodies against mumps, that in nearly all cases had been generated by the use of the mumps vaccine.