Considerations for NIR-I and short-wave infrared (SWIR) fluorescence imaging within a clinical operating room.

Short-wave infrared (SWIR/NIR-II) fluorescence imaging has received increased attention for use in fluorescence-guided surgery (FGS) due to the potential for higher resolution imaging of subsurface structures and reduced autofluorescence compared to conventional NIR-I imaging. As with any fluorescence imaging modality introduced in the operating room, an appropriate accounting of contaminating background signal from other light sources in the operating room is an important step. Herein, we report the background signals in the SWIR and NIR-I emitted from commonly-used equipment in the OR, such as ambient and operating lights, LCD screens and surgical guidance systems. These results can guide implementation of protocols to reduce background signal.

Management of the thyroid gland during laryngectomy.

OBJECTIVES: This study aimed to: describe the incidence of thyroid gland involvement in advanced laryngeal cancer, analyse patterns of spread to the thyroid and elucidate predictors of thyroid involvement. METHODS: A retrospective review was performed on patients who underwent laryngectomy from 1991 to 2015 as a primary or salvage treatment for squamous cell carcinoma of the larynx, hypopharynx or base of tongue. The incidence of thyroidectomy during total laryngectomy, type of thyroidectomy, incidence of gland involvement, route of spread, and positive predictors of spread were analysed and reported. RESULTS: A total of 188 patients fit the inclusion criteria. Of these, 125 (66 per cent) underwent thyroidectomy. The thyroid was involved in 10 of the 125 patients (8 per cent), 9 by direct extension and 1 by metastasis. Cartilage invasion was a predictor of thyroid gland involvement, with a positive predictive value of 26 per cent. CONCLUSION: There is a low incidence of thyroid gland involvement in laryngeal carcinoma. Most cases of gland involvement occurred by direct extension. Thyroidectomy during laryngectomy should be considered for advanced stage tumours with cartilage invasion.

Functional study of four neurotoxins as inhibitors of post-traumatic nerve regeneration.

OBJECTIVES/HYPOTHESIS: Chemical inhibition of nerve regeneration was studied as a potential adjunct in the treatment of injuries to the facial or recurrent laryngeal nerve. We propose that by treating selected muscles with an inhibitor of nerve regeneration shortly after injury, synkinesis may be controlled. STUDY DESIGN: Nerve regeneration after crush injury was studied in the rat posterior tibial and sciatic nerves, well-established models for the study of peripheral nerve injuries. METHODS: Four days after controlled crush injury to the posterior tibial nerve, the gastrocnemius muscle was injected with saline (control, n = 8), phenol (n = 6), doxorubicin (n = 6), or vincristine (n = 11). Injection without crush injury was performed using vincristine (n = 4) or botulinum toxin (n = 4). Four rats underwent crush injury to the sciatic nerve followed 4 days later by botulinum toxin injection to the gastrocnemius muscle. The percent of functional recovery (%FR) of the nerve was assessed using walking track analysis. RESULTS: Vincristine significantly retarded nerve regeneration. Five weeks after injury, %FR returned to normal in controls, as well as in the phenol, doxorubicin, and botulinum toxin groups, while in the vincristine group %FR was less than 60% of baseline (P <.0001). Vincristine injections without crush injury showed no significant reduction in print length factor. Functional recovery in the botulinum/crush group was more rapid than the botulinum without crush group. CONCLUSIONS: Application of vincristine to the gastrocnemius muscle significantly inhibits regeneration of the posterior tibial nerve after crush injury. Botulinum toxin does not prolong functional recovery after nerve injury; rather, crush injury protects against the prolonged chemodenervation seen with botulinum toxin. Doxorubicin and phenol injection did not prolong functional recovery at the doses tested.

Factors related to outcome of salvage therapy for isolated cervical recurrence of squamous cell carcinoma in the previously treated neck: a multi-institutional study.

OBJECTIVE: The goal was to identify factors associated with the outcome of salvage therapy for patients with isolated cervical recurrences of squamous cell carcinoma in the previously treated neck (ICR-PTN). STUDY DESIGN AND SETTINGS: A tumor registry search for ICR-PTN patients was performed at 7 participating institutions, and the charts were reviewed. Kaplan-Meier plots for survival and time until re-recurrence were used to evaluate the significance of associated variables. RESULTS: Median survival and time until re-recurrence were both 11 months. Survival was better in patients with the following characteristics: nonsurgical initial neck treatment, negative initial disease resection margins, no history of prior recurrence, ipsilateral location of the ICR-PTN relative to the primary, and use of surgical salvage. CONCLUSIONS: By pooling the experience of 7 US tertiary care medical centers, we have identified 5 factors that are associated with outcome of salvage therapy for ICR-PTN. SIGNIFICANCE: Consideration of these factors, as well as the reviewed literature, should facilitate patient selection for salvage protocols.

Auricular leishmaniasis mimicking squamous cell carcinoma.

OBJECTIVES: We report a rare case of auricular involvement by leishmaniasis, in order to demonstrate the importance of thorough investigation of cutaneous head and neck lesions, and also the importance of inclusion of infections such as leishmaniasis in the differential diagnosis of auricular lesions, especially in endemic areas. CASE HISTORY: A 42-year-old man with multiple lesions on his head, neck and hands was referred to our centre. He had the following lesions: a painful, crusted, 8 x 8 cm plaque with indurated margins on the left parotid region and auricle; a red papule on the right temporal region; an ulcerative lesion on the skin overlying the proximal interphalangeal joint of the fifth finger of the right hand; and a bluish papule on the neck. Although histopathological examination of the Geimsa-stained specimen was misleading, a direct smear prepared from biopsies showed amastigotes, and therapy resulted in complete recovery. CONCLUSION: Leishmaniasis can be both under- or over-diagnosed. Especially in endemic areas, parasitic causes of chronic infections should always be kept in mind.

Phase resetting of the respiratory oscillator by carotid sinus nerve stimulation in cats.

1. Stimulation of the carotid sinus nerve causes an increase in inspiratory (I) and expiratory (E) neural activities. If central respiratory oscillation is generated by an attractor-cycle process, an increase in its activity can be caused by a centrifugal perturbation of state. We evaluated this hypothesis by comparing the respiratory oscillator's phase responses to carotid sinus nerve stimulations in cats to the phase responses of an attractor-cycle oscillator, the Bonhoeffer-van der Pol (BvP) equations, subjected to centrifugal perturbations. 2. We recorded phrenic activity in seven anaesthetized, vagotomized, glomectomized, paralysed and servo-ventilated cats. Carotid sinus nerve (CSN) stimulation with 0.5-0.8 s electrical pulse trains increased the immediate cycle period and delayed the onset of breaths after stimulation in a highly predictable manner, with the exception that strong stimuli (25 Hz, 0.25-0.90 V) caused unpredictable responses when given at the I-E or the E-I transitions. The resetting plots exhibited focal gaps corresponding to these unpredictable responses, and the size of the gaps increased with increases in the strength of CSN stimulation. Type 0 resetting was not achieved despite the large perturbations in rhythm induced by CSN stimulation. 3. Centrifugal perturbations of the BvP oscillator resulted in phase responses which were similar to those found in the animal experiments. The BvP cycle had two critical phases at which phase resetting was highly irregular and neighbouring state trajectories were highly divergent. The resetting plots had focal gaps that increased in size with increases in the strength of perturbation. The gaps did not represent true discontinuity because at higher computational resolution the resetting plots appeared to be steep but smooth portions of topological Type 1 resetting curves. 4. These studies support the concept that brief carotid sinus nerve stimulations cause a transient outward displacement of the central respiratory state away from its attractor cycle, in contrast to the unidirectional displacements that accompany midbrain reticular or superior laryngeal nerve stimulations. The findings define particular geometrical relationships between oscillatory state trajectories of the rhythm generator and perturbed state trajectories induced by inputs to the oscillator. These relationships provide a framework for developing and testing the validity of neural models of the respiratory oscillator.

The wagon wheel illusion in movies and reality.

Wheels turning in the movies or in other forms of stroboscopic presentation often appear to be rotating backward. Remarkably, a similar illusion is also seen in continuous light. The occurrence of this perception in the absence of intermittent illumination suggests that we normally see motion, as in movies, by processing a series of visual episodes.