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Brian J. Park, Colin J. Gold, David Christianson, Nicole A. DeVries Watson, Kirill V. Nourski, Royce W. Woodroffe, and Patrick W. Hitchon

OBJECTIVE

Adjacent-segment disease (ASD) proximal to lumbosacral fusion is assumed to result from increased stress and motion that extends above or below the fusion construct. Sublaminar bands (SBs) have been shown to potentially mitigate stresses in deformity constructs. A similar application of SBs in lumbar fusions is not well described yet may potentially mitigate against ASD.

METHODS

Eight fresh-frozen human cadaveric spine specimens were instrumented with transforaminal lumbar interbody fusion (TLIF) cages at L3–4 and L4–5, and pedicle screws from L3 to S1. Bilateral SBs were applied at L2 and tightened around the rods extending above the L3 pedicle screws. After being mounted on a testing frame, the spines were loaded at L1 to 6 Nm in all 3 planes, i.e., flexion/extension, right and left lateral bending, and right and left axial rotation. Motion and intradiscal pressures (IDPs) at L2–3 were measured for 5 conditions: intact, instrumentation (L3–S1), band tension (BT) 30%, BT 50%, and BT 100%.

RESULTS

There was significant increase in motion at L2–3 with L3–S1 instrumentation compared with the intact spine in flexion/extension (median 8.78°, range 4.07°–10.81°, vs median 7.27°, range 1.63°–9.66°; p = 0.016). When compared with instrumentation, BT 100% reduced motion at L2–3 in flexion/extension (median 8.78°, range 4.07°–10.81°, vs median 3.61°, range 1.11°–9.39°; p < 0.001) and lateral bending (median 6.58°, range 3.67°–8.59°, vs median 5.62°, range 3.28°–6.74°; p = 0.001). BT 50% reduced motion at L2–3 only in flexion/extension when compared with instrumentation (median 8.78°, range 4.07°–10.81°, vs median 5.91°, range 2.54°–10.59°; p = 0.027). There was no significant increase of motion at L1–2 with banding when compared with instrumentation, although an increase was seen from the intact spine with BT 100% in flexion/extension (median 5.14°, range 2.47°–9.73°, vs median 7.34°, range 4.22°–9.89°; p = 0.005). BT 100% significantly reduced IDP at L2–3 from 25.07 psi (range 2.41–48.08 psi) before tensioning to 19.46 psi (range −2.35 to 29.55 psi) after tensioning (p = 0.016).

CONCLUSIONS

In this model, the addition of L2 SBs reduced motion and IDP at L2–3 after the L3–S1 instrumentation. There was no significant increase in motion at L1–2 in response to band tensioning compared with instrumentation alone. The application of SBs may have a clinical application in reducing the incidence of ASD.

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Yasunori Nagahama, Christopher K. Kovach, Michael Ciliberto, Charuta Joshi, Ariane E. Rhone, Adam Vesole, Phillip E. Gander, Kirill V. Nourski, Hiroyuki Oya, Matthew A. Howard III, Hiroto Kawasaki, and Brian J. Dlouhy

Musicogenic epilepsy (ME) is an extremely rare form of the disorder that is provoked by listening to or playing music, and it has been localized to the temporal lobe. The number of reported cases of ME in which intracranial electroencephalography (iEEG) has been used for seizure focus localization is extremely small, especially with coverage of the superior temporal plane (STP) and specifically, Heschl’s gyrus (HG). The authors describe the case of a 17-year-old boy with a history of medically intractable ME who underwent iEEG monitoring that involved significant frontotemporal coverage as well as coverage of the STP with an HG depth electrode anteriorly and a planum temporale depth electrode posteriorly. Five seizures occurred during the monitoring period, and a seizure onset zone was localized to HG and the STP. The patient subsequently underwent right temporal neocortical resection, involving the STP and including HG, with preservation of the mesial temporal structures. The patient remains seizure free 1 year postoperatively. To the authors’ knowledge, this is the first reported case of ME in which the seizure focus has been localized to HG and the STP with iEEG monitoring. The authors review the literature on iEEG findings in ME, explain their approach to HG depth electrode placement, and discuss the utility of STP depth electrodes in temporal lobe epilepsy.

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Taylor J. Abel, Royce W. Woodroffe, Kirill V. Nourski, Toshio Moritani, Aristides A. Capizzano, Patricia Kirby, Hiroto Kawasaki, Matthew Howard III, and Mary Ann Werz

OBJECTIVE

A convergence of clinical research suggests that the temporal pole (TP) plays an important and potentially underappreciated role in the genesis and propagation of seizures in temporal lobe epilepsy (TLE). Understanding its role is becoming increasingly important because selective resections for medically intractable TLE spare temporopolar cortex (TPC). The purpose of this study was to characterize the role of the TPC in TLE after using dense electrocorticography (ECoG) recordings in patients undergoing invasive monitoring for medically intractable TLE.

METHODS

Chronic ECoG recordings were obtained in 10 consecutive patients by using an array customized to provide dense coverage of the TP as part of invasive monitoring to localize the epileptogenic zone. All patients would eventually undergo cortico-amygdalohippocampectomy. A retrospective review of the patient clinical records including ECoG recordings, neuroimaging studies, neuropathology reports, and clinical outcomes was performed.

RESULTS

In 7 patients (70%), the TP was involved at seizure onset; in 7 patients (70%), there were interictal discharges from the TP; and in 1 case, there was early spread to the TP. Seizure onset in the TP did not necessarily correlate with preoperative neuroimaging abnormalities of the TP.

CONCLUSIONS

These data demonstrate that TPC commonly plays a crucial role in temporal lobe seizure networks. Seizure onset from the TP would not have been predicted based on available neuroimaging data or interictal discharges. These findings illustrate the importance of thoroughly considering the role of the TP prior to resective surgery for TLE, particularly when selective mesial resection is being considered.