Feasibility of virtual surgical simulation in the head and neck region for soft tissue reconstruction using free flap: a comparison of preoperative and postoperative volume measurement.

In the head and neck region, preoperative evaluation of the free flap volume is challenging. The current study validated preoperative three-dimensional (3D) virtual surgical simulation for soft tissue reconstruction by assessing flap volume and evaluated fat and muscle volume changes at follow-up in 13 head and neck cancer patients undergoing anterolateral craniofacial resection. Patients received 3D virtual surgical simulation, and the volume of the planned defects was estimated by surgical simulation. Following en bloc resection of the tumor, the defect in the skull base was covered using a rectus abdominis myocutaneous flap. Following surgery, computed tomography scans were acquired at day 1 and at 6 and 12 months. Virtual planned defect was on average 227 ml (range, 154-315) and was 10% smaller than the actual flap volume in patients without skin involvement of the tumor. Between day 1 and 12 months post-surgery, the volume of fat and muscle tissue in the free flap dropped by 9% and 58%, respectively. Our results indicate that 3D virtual surgical simulation provides essential information in determining the accurate volume of the required free flap for surgical defect repair and may thus help improve surgical planning and functional and esthetic outcome.

Autologous fat injection therapy including a high concentration of adipose-derived regenerative cells in a vocal fold paralysis model: animal pilot study.

OBJECTIVES: To verify the effectiveness and safety of the addition of adipose-derived regenerative cells to autologous fat injection therapy. METHODS: Unilateral vocal fold paralysis models were made by cutting the right recurrent laryngeal nerve in two pigs. At day 30, 0.5 ml adipose-derived regenerative cells mixed with 1 ml autologous fat was injected into the right vocal fold of one pig, with the other receiving 0.5 ml Ringer's solution mixed with 1 ml autologous fat. At day 120, fibrescopy, laser Doppler flowmeter, computed tomography, vocal function evaluation and histological assessment were conducted. RESULTS: Although histological assessment revealed atrophy of the thyroarytenoid muscle fibre in both pigs, there was remarkable hypertrophy of the thyroarytenoid muscle fibre in the area surrounding the adipose-derived regenerative cells injection site. CONCLUSION: The addition of a high concentration of adipose-derived regenerative cells to autologous fat injection therapy has the potential to improve the treatment outcome for unilateral vocal fold paralysis.

Effects of lowering barometric pressure on guarding behavior, heart rate and blood pressure in a rat model of neuropathic pain.

We investigated whether lowering barometric pressure by 20 mmHg (LP) aggravates the guarding behavior suggestive of spontaneous pain following sciatic nerve chronic constriction injury (CCI) in rats. Systemic blood pressure (BP) and heart rate (HR) of unrestrained rats were recorded telemetrically during LP both before and after the CCI surgery. CCI rats showed guarding posture in normopressure conditions, and LP increased the cumulative time of this behavior. Baseline BP but not HR was increased following CCI. LP increased BP and HR of the rats only before the CCI surgery. Animals after CCI surgery showed variable (BP, HR) and transient (HR) responses to LP. These results indicate that (1) LP aggravated spontaneous pain and increased BP and HR in the CCI rats, and (2) CCI surgery influenced BP and HR of rats.

Effects of lowering ambient temperature on pain-related behaviors in a rat model of neuropathic pain.

To clarify the mechanism by which changes in chronic pain are induced by cold environments, rats rendered neuropathic by a chronic constriction injury (CCI) to the sciatic nerve were exposed to low ambient temperature (LT; 7 degrees C decrease from 22 degrees C) in a climate-controlled room. LT exposure aggravated pain-related behaviors in CCI rats, i.e., decreased the threshold to von Frey hair and paw pressure stimulation, prolonged the duration of foot withdrawal to pinprick stimulation, and increased the cumulative duration of guarding posture. Lumbar sympathectomy (SYX) did not inhibit LT-induced augmentations of pain-related behaviors in CCI rats. LT exposure decreased the skin temperatures of both hind paws to the same degree in the sham-operated control and SYX rats, while in the CCI and SYX+CCI rats it caused a larger temperature decrease in the injured paw than in the uninjured one. These results indicate that LT exposure augments abnormalities in pain-related behaviors of neuropathic rats, and also suggest that sympathetic nervous activity is not a predominant factor in the augmenting mechanism.