Background and Study Aims Various minimally invasive approaches are used in neurosurgery. Surgeons must perform nondynamic fine movements in a narrow corridor, so specially designed surgical devices are essential. Unsophisticated instruments may pose potential hazards. The purpose of this study was to assess the factors associated with muscle fatigue during minimally invasive neurosurgery and to investigate whether physical stress can be reduced by refining the devices used. Material and Methods Four physical aspects of a handpiece were investigated: torque of conduits (0.20, 0.28, and 0.37 kgf*cm), shape of hand grip (five types), angle of the nozzle (0, 20, and 40 degrees), and weight balance (neutral, proximal, and distal). To evaluate muscle fatigue, surface electromyography was recorded from the extensor carpi radialis muscle and flexor carpi radialis muscle during a geometric tracing task. The maximum voluntary contraction (MVC) of each muscle and %MVC (muscle contraction during a task/MVC × 100) were used as the indexes of muscle fatigue. Results The shape of the hand grip significantly reduced %MVC, which is associated with muscle fatigue. The torque of conduits and angle of the nozzle tended to reduce muscle fatigue but not significantly. Weight balance did not affect muscle fatigue. Based on these results, we made two refined models: model α (torque of conduits 0.2 kgf*cm, angle of nozzle 20 degrees, neutral balance, hand grip with a 2.9 × 2.0-cm oval section with angled finger rest), and model β (torque of conduits 0.2 kgf*cm, angle of nozzle 20 degrees, neutral balance, hand grip with a 2.9-cm round section with a curved finger rest). The %MVC was significantly decreased with both types (p < 0.05 and p < 0.01, respectively), indicating reduction of muscle fatigue. Conclusions The geometrically refined surgical device can improve muscle load during surgery and reduce the surgeon's physical stress, thus minimizing the risk of complications.

Anti-thrombotic drugs may increase the risk for chronic subdural hematoma (CSDH). However, whether to continue or discontinue/counteract these drugs has not been investigated in patients with mild head trauma. CSDH incidence after mild head trauma, as well as the risk for CSDH in patients with anti-thrombotic drugs, were investigated in this study. The study included 765 consecutive elderly (>65 y.o.) patients with mild head trauma and an initial Glasgow Coma Scale (GCS) score of 14 or 15. All patients received initial CT within 24 hours after trauma and were re-examined 30 days after trauma to detect CSDH formation, repeating for every 30 days to examine symptomatic CSDH progression. Patients were divided into two groups, with anti-thrombotic drugs (n = 195) or without them (n = 263), to investigate the influence of pre-traumatic conditioning with anti-thrombotic drugs on CSDH. The whole sample was 458 out of 765 cases. The incidence of CSDH formation was 91 out of 458 cases (19.9%) after mild head trauma, with no significant difference between with and without anti-thrombotic drugs. CSDH progressed as symptomatic in 21 out of 458 cases (4.6%), with no significant difference between with and without anti-thrombotic drugs. Pre-traumatic conditioning with anti-thrombotic drugs and its continuation after trauma did not affect the incidence of formation or symptomatic progression of CSDH. This finding suggests that discontinuing and/or counteracting antithrombotic drugs may be unnecessary in patients with mild head trauma.

Choroid plexus carcinomas (CPCs) are rare malignant tumors of neuro-ectodermal origin, accounting for less than 1% of all intracranial tumors. The recurrence rates of CPCs are very high and typically occur in the short-term following surgery, even after gross total removal. Here we present a rare case of CPC with spinal metastasis, which occurred long after its initial presentation. A 25-year-old woman with a history of increased intracranial pressure underwent resection for a tumor of the fourth ventricle, with a histopathological diagnosis of CPC. After tumor resection, she received 30 Gy of radiation therapy to the craniospinal axis and 20 Gy to the primary site, followed by nimustine hydrochloride chemotherapy. The residual lesion completely responded to these treatments. She suffered sensory loss in the sacral region 13 years later, followed by refractory skin ulcer in the sacral region 17 years after the initial treatments. Magnetic resonance imaging at 17 years after the initial treatments showed tumor in the sacral region, which was enlarged upon follow-up after 18 months, causing incontinence and loss of urinary intention. She underwent tumor resection, with a histological diagnosis of recurrent CPC. She received salvage re-irradiation. This case shows that CPC can spread via the cerebrospinal fluid pathways and cause spinal metastasis, with relatively slow clinical course. The present case suggests that patients with CPCs may need long-term follow-up imaging of the total neural axis to identify late recurrence at both the primary site and spinal metastasis.

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