Shinsuke Tominaga

Lumbar Degenerative Spondylolisthesis: Changes in Surgical Indications and Comparison of Instrumented Fusion With Two Surgical Decompression Procedures.

Study Design. Single-center retrospective case series. Objective. To compare outcomes of instrumented fusion and two methods of decompression for degenerative spondylolisthesis. Summary of Background Data. There is no consensus on the surgical indications or optimum techniques for lumbar degenerative spondylolisthesis. Methods. We analyzed the data of 140 patients treated by fusion (n = 80; mean follow-up, 77.9 months) or decompression (n = 60; mean follow-up, 38.0 months) and examined changes in surgical indications over a 12-year period. We compared the outcomes of instrumented fusion with the outcomes of two decompression techniques, the first employing a unilateral approach for bilateral decompression and the second employing a bilateral approach for contralateral decompression, with contralateral foraminal decompression as needed. Postoperative evaluation was made at the final follow-up visit beginning in 2007 by analyzing patient interviews and neurological examination data. We compared results with the Japanese Orthopedic Association symptom score before surgery and at final follow-up. Results. Surgical indications for fusion narrowed over time, with fusion used less frequently and decompression used more frequently. Similar decreases in clinical symptoms, including low back pain, were achieved with all methods. In the decompression groups, preoperative slip distance and instability, and postoperative slip progression or development of instability, did not correlate significantly with clinical outcome. Slip progression occurred in 8 of 10 levels in patients with preoperative translation ≥5 mm, but these patients showed no increase in instability, defined as translation ≥ 2 mm, at final follow-up. Conclusion. Our findings raise a question about the value of the radiologic criteria for performing fusion used in the late period, namely translation ≥5 mm and/or rotation ≥ 10°. If discogenic pain is excluded, decompression alone may be suitable even for patients with severe low back pain and translation ≥5 mm. Level of Evidence: 4

Masseteric nerve transfer for short-term facial paralysis following skull base surgery.

BACKGROUND Nerve transfers have been widely used to reanimate paralyzed facial muscles after irreversible proximal injuries to the facial nerve. The author has developed a technique involving masseteric nerve transfer combined with cross-facial nerve grafting for treating skull base surgery-induced facial paralysis. This paper aims to demonstrate that this procedure is effective and causes negligible donor site morbidity. METHODS Seven patients who developed facial paralysis after the removal of skull base tumors were treated with masseteric nerve transfer combined with cross-facial nerve grafting with the aim of reanimating the midface. The mean period of preoperative paralysis was 6 months. The follow-up period ranged from 22 to 65 months (mean: 46 months). The patients were evaluated with physical examinations and video analysis. RESULTS Successful reanimation of the midface was achieved in all patients except one, whose muscle tone recovered. On average, facial motion developed 4 months after the nerve transfer. Only minimal coordinated eyelid movement was seen during biting. None of the patients experienced impaired masticatory function or visible wasting of the masseter muscle. All of the patients who recovered the ability to contract their paralyzed muscles were able to close their eyes tightly during biting; however, none of the patients have been able to achieve an effortless spontaneous smile. CONCLUSIONS Masseteric nerve transfer is an alternative method for selective reanimation of the midface and does not cause donor site morbidity.

Titanium Mesh Implant Exposure Due To Pressure Gradient Fluctuation

OBJECTIVE Titanium mesh implants (TMIs) are used for various purposes in craniotomy. Although delayed implant exposure and thinning of the overlying skin are well-known complications, the mechanism has not yet been elucidated. We reviewed our cases and propose a mechanism for TMI exposure. METHODS From 2009 to 2018, we treated 14 patients with delayed titanium implant exposure after craniotomy. The exposed titanium implant was a TMI in 4 patients, a titanium mesh plate in 6 patients, and a titanium fixation plate with holes in 4 patients. We reviewed the preoperative computed tomography (CT) scans and operative findings. RESULTS The interval between craniotomy and implant exposure was 13 years (range, 5-27). Implant exposure occurred at the temporal region in 7 patients, frontal region in 6 patients, and parietal region in 1 patient. The skin ulcer size ranged from 0.25 to 10 cm2 (mean, 1.95). In the patients with TMI exposure, the dura was expanded, and no residual epidural space was identified on the CT scans; however, epidural dead space was revealed on the CT scan in the patients with titanium mesh plate or titanium fixation plate exposure. CONCLUSIONS We believe that the key factor resulting in delayed titanium mesh exposure is the pressure gradient between the atmosphere and the intracranial space. Fluctuation of this gradient exerts dynamic stress on the tissue in the mesh holes and the adjacent tissue, resulting in tissue damage and implant exposure.