Patient Positioning During In-Office Otologic Procedures Impacts Physician Ergonomics.

OBJECTIVE: The purpose of this study was to evaluate the impact of patient positioning on physician ergonomics during in-office otologic procedures. A previous simulation study suggested that placing patients supine during in-office otology procedures is ergonomically favorable. This study aims to substantiate these findings during the routine care of patients in an otolaryngology practice setting. STUDY DESIGN: Observational study. SETTING: Outpatient otology clinic within tertiary care facility. STUDY SUBJECTS: Two neurotology attending physicians. INTERVENTIONS: Physicians performed cerumen removal procedures in the office with patients either in the seated position (n = 24) or supine position (n = 24). MAIN OUTCOME MEASURES: The rapid upper limb assessment (RULA), a validated instrument that measures body positioning with a focus on the upper arm, was used to measure ergonomic positioning. RULA scores correlate occupational body positioning with a numeric representation of musculoskeletal injury risk ranging from 1 (minimal risk) to 7 (very high risk). RESULTS: Overall median RULA scores were 4.5 (medium risk) with patients in the seated position, and 2 (low risk) with patients in the supine position (p < 0.0001). Similarly, RULA scores were significantly lower with patients in the supine position when each physician was evaluated independently (p < 0.0001, for both). CONCLUSIONS: Placing patients in a supine position for cerumen removal results in more favorable ergonomic positioning for the physician, thus reducing risk for work-related musculoskeletal disorders. This suggests that physicians should consider placing patients in the supine position for in-office otologic procedures. Further study is needed to investigate optimal ergonomic positioning for other common otolaryngology procedures.

Neurons in the pontomedullary reticular formation receive converging inputs from the hindlimb and labyrinth.

The integration of inputs from vestibular and proprioceptive sensors within the central nervous system is critical to postural regulation. We recently demonstrated in both decerebrate and conscious cats that labyrinthine and hindlimb inputs converge onto vestibular nucleus neurons. The pontomedullary reticular formation (pmRF) also plays a key role in postural control, and additionally participates in regulating locomotion. Thus, we hypothesized that like vestibular nucleus neurons, pmRF neurons integrate inputs from the limb and labyrinth. To test this hypothesis, we recorded the responses of pmRF neurons to passive ramp-and-hold movements of the hindlimb and to whole-body tilts, in both decerebrate and conscious felines. We found that pmRF neuronal activity was modulated by hindlimb movement in the rostral-caudal plane. Most neurons in both decerebrate (83% of units) and conscious (61% of units) animals encoded both flexion and extension movements of the hindlimb. In addition, hindlimb somatosensory inputs converged with vestibular inputs onto pmRF neurons in both preparations. Pontomedullary reticular formation neurons receiving convergent vestibular and limb inputs likely participate in balance control by governing reticulospinal outflow.

Optimizing Positioning for In-Office Otology Procedures.

Objective Surgeons often report musculoskeletal discomfort in relation to their practice, but few understand optimal ergonomic positioning. This study aims to determine which patient position-sitting versus supine-is ergonomically optimal for performing otologic procedures. Study Design Observational study. Setting Outpatient otolaryngology clinic setting in a tertiary care facility. Subjects and Methods We observed 3 neurotologists performing a standardized simulated cerumen debridement procedure on volunteers in 2 positions: sitting and supine. The Rapid Upper Limb Assessment (RULA)-a validated tool that calculates stress placed on the upper limb during a task-was used to evaluate ergonomic positioning. Scores on this instrument range from 1 to 7, with a score of 1 to 2 indicating negligible risk of developing posture-related injury. The risk of musculoskeletal disorders increases as the RULA score increases. Results In nearly every trial, RULA scores were lower when the simulated patient was placed in the supine position. When examined as a group, the median RULA scores were 5 with the patient sitting and 3 with the patient in the supine position ( P < .0001). When the RULA scores of the 3 neurotologists were examined individually, each had a statistically significant decrease in score with the patient in the supine position. Conclusion This study indicates that patient position may contribute to ergonomic stress placed on the otolaryngologist's upper limb during in-office otologic procedures. Otolaryngologists should consider performing otologic procedures with the patient in the supine position to decrease their own risk of developing upper-limb musculoskeletal disorders.

Vestibular nucleus neurons respond to hindlimb movement in the conscious cat.

The limbs constitute the sole interface with the ground during most waking activities in mammalian species; it is therefore expected that somatosensory inputs from the limbs provide important information to the central nervous system for balance control. In the decerebrate cat model, the activity of a subset of neurons in the vestibular nuclei (VN) has been previously shown to be modulated by hindlimb movement. However, decerebration can profoundly alter the effects of sensory inputs on the activity of brain stem neurons, resulting in epiphenomenal responses. Thus, before this study, it was unclear whether and how somatosensory inputs from the limb affected the activity of VN neurons in conscious animals. We recorded brain stem neuronal activity in the conscious cat and characterized the responses of VN neurons to flexion and extension hindlimb movements and to whole body vertical tilts (vestibular stimulation). Among 96 VN neurons whose activity was modulated by vestibular stimulation, the firing rate of 65 neurons (67.7%) was also affected by passive hindlimb movement. VN neurons in conscious cats most commonly encoded hindlimb movement irrespective of the direction of movement (n = 33, 50.8%), in that they responded to all flexion and extension movements of the limb. Other VN neurons overtly encoded information about the direction of hindlimb movement (n = 27, 41.5%), and the remainder had more complex responses. These data confirm that hindlimb somatosensory and vestibular inputs converge onto VN neurons of the conscious cat, suggesting that VN neurons integrate somatosensory inputs from the limbs in computations that affect motor outflow to maintain balance.

Responses of vestibular nucleus neurons to inputs from the hindlimb are enhanced following a bilateral labyrinthectomy.

Vestibular nucleus neurons have been shown to respond to stimulation of afferents innervating the limbs. However, a limitation in the potential translation of these findings is that they were obtained from decerebrate or anesthetized animals. The goal of the present study was to determine whether stimulation of hindlimb nerves similarly affects vestibular nucleus neuronal activity in conscious cats, and whether the responsiveness of neurons to the stimuli is altered following a bilateral labyrinthectomy. In labyrinth-intact animals, the firing rate of 24/59 (41%) of the neurons in the caudal vestibular nucleus complex was affected by hindlimb nerve stimulation. Most responses were excitatory; the median response latency was 20 ms, but some units had response latencies as short as 10 ms. In the first week after a bilateral labyrinthectomy, the proportion of vestibular nucleus neurons that responded to hindlimb nerve stimulation increased slightly (to 24/55 or 44% of units). However, during the subsequent postlabyrinthectomy survival period, the proportion of vestibular nucleus neurons with hindlimb inputs increased significantly (to 30/49 or 61% of units). Stimuli to hindlimb nerves needed to elicit neuronal responses was consistently over three times the threshold for eliciting an afferent volley. These data show that inputs from hindlimb afferents smaller than those innervating muscle spindles and Golgi tendon organs affect the processing of information in the vestibular nuclei, and that these inputs are enhanced following a bilateral labyrinthectomy. These findings have implications for the development of a limb neuroprosthetics device for the management of bilateral vestibular loss.

Processing of vestibular inputs by the medullary lateral tegmental field of conscious cats: implications for generation of motion sickness.

The dorsolateral reticular formation of the caudal medulla, the lateral tegmental field (LTF), participates in generating vomiting. LTF neurons exhibited complex responses to vestibular stimulation in decerebrate cats, indicating that they received converging inputs from a variety of labyrinthine receptors. Such a convergence pattern of vestibular inputs is appropriate for a brain region that participates in generating motion sickness. Since responses of brainstem neurons to vestibular stimulation can differ between decerebrate and conscious animals, the current study examined the effects of whole-body rotations in vertical planes on the activity of LTF neurons in conscious felines. Wobble stimuli, fixed-amplitude tilts, the direction of which moves around the animal at a constant speed, were used to determine the response vector orientation, and also to ascertain whether neurons had spatial-temporal convergence (STC) behavior (which is due to the convergence of vestibular inputs with different spatial and temporal properties). The proportion of LTF neurons with STC behavior in conscious animals (25 %) was similar to that in decerebrate cats. Far fewer neurons in other regions of the feline brainstem had STC behavior, confirming findings that many LTF neurons receive converging inputs from a variety of labyrinthine receptors. However, responses to vertical plane vestibular stimulation were considerably different in decerebrate and conscious felines for LTF neurons lacking STC behavior. In decerebrate cats, most LTF neurons had graviceptive responses to rotations, similar to those of otolith organ afferents. However, in conscious animals, the response properties were similar to those of semicircular canal afferents. These differences show that higher centers of the brain that are removed during decerebration regulate the labyrinthine inputs relayed to the LTF, either by gating connections in the brainstem or by conveying vestibular inputs directly to the region.