Sensory Outcomes Research Articles

MR Spectroscopy of the Cervical Spinal Cord in Chronic Spinal Cord Injury.

Purpose To investigate metabolic changes in chronic spinal cord injury (SCI) by applying MR spectroscopy in the cervical spinal cord. Materials and Methods Single-voxel short-echo spectroscopic data in study participants with chronic SCI and healthy control subjects were prospectively acquired in the cervical spinal cord at C2 above the level of injury between March 2016 and January 2017 and were compared between groups. Concentrations of total N-acetylaspartate (tNAA), myo-inositol (mI), total choline-containing compounds (tCho), creatine, and glutamine and glutamate complex were estimated from the acquired spectra. Participants were assessed with a comprehensive clinical evaluation investigating sensory and motor deficits. Correlation analysis was applied to investigate relationships between observed metabolic differences, lesion severity, and clinical outcome. Results There were 18 male study participants with chronic SCI (median age, 51 years; range, 30-68 years) and 11 male healthy control subjects (median age, 45 years; range, 30-67 years). At cervical level C2, tNAA/mI and tCho/mI ratios were lower in participants with SCI (tNAA/mI: -26%, P = .003; tCho/mI: -18%; P = .04) than in healthy control subjects. The magnitude of difference was greater with the severity of cord atrophy (tNAA/mI: R2 = 0.44, P = .003; tCho/mI: R2 = 0.166, P = .09). Smaller tissue bridges at the lesion site correlated with lower ratios of tNAA/mI (R2 = 0.69, P = .006) and tCho/mI (R2 = 0.51, P = .03) at the C2 level. Lower tNAA/mI and tCho/mI ratios were associated with worse sensory and motor outcomes (P < .05). Conclusion Supralesional metabolic alterations are observed in chronic spinal cord injury, likely reflecting neurodegeneration, demyelination, and astrocytic gliosis in the injured cervical cord. Lesion severity and greater clinical impairment are both linked to the biochemical changes in the atrophied cervical cord after spinal cord injury. © RSNA, 2019 Online supplemental material is available for this article. See also the editorial by Lin in this issue.

Reconstruction of digit planer injuries using component transfer of double second toes: A case report

The purpose of this report is to show that customized component second-toe transfers may improve functional and aesthetic outcomes following bone, soft tissue, and joint destruction of traumatically injured digits. A 22-year-old male sustained a planer injury resulting in loss of the distal volar soft tissues of the middle, ring, and small fingers, along with variable destruction of middle phalanges and distal interphalangeal joints. Simultaneous vascularized second-toe transfers were performed with customized joint and pulp reconstruction of middle and small fingers. The ring finger was salvaged using non-vascularized autologous bone graft and acellular dermal matrix. The patient had an uncomplicated postoperative course. Five-year strength, sensory and patient reported outcomes represent overall satisfactory results. Strength testing revealed the injured hand to perform within 90% strength of the uninjured side. Sensory outcomes showed present but diminished sensory perception in each of the injured digits. The patient's upper extremity function, physical health, quality of life, and foot health were overall acceptable, and he returned to using his hand for typing, writing, weight-lifting, and woodworking.

Measures to improve wine malolactic fermentation.

This review focuses on the considerable amount of research that has been directed towards the improvement of efficiency and reliability of malolactic fermentation (MLF), which is important in winemaking. From this large body of work, it is clear that reliable MLF is essential for process efficiency and prevention of spoilage in the final product. Impediments to successful MLF in wine, the impact of grape and wine ecology and how this may affect MLF outcome are discussed. Further focus is given to how MLF success may be enhanced, via alternative inoculation strategies, MLF progress sensing technologies and the use of different bacterial species. An update of how this information may be used to enhance and improve sensory outcomes through metabolite production during MLF and suggestions for future research priorities for the field are also provided.

Microscopic Keyhole Technique for Surgical Removal of Thoracic Spinal Meningiomas

The aim of this study was to evaluate the safety and efficacy of the microscopic minimally invasive keyhole technique for surgical resection of thoracic spinal meningiomas. Seventeen consecutive patients with thoracic spinal meningiomas were included in the series from May 2015 to August 2017. All patients were treated using a microscopic keyhole technique through a tubular retractor system. The demographic data and perioperative variables were recorded. At last follow-up, clinical outcome was assessed using the visual analog scale for pain and the American Spinal Injury Association scale for motor and sensory outcome. All patients underwent microscopic keyhole surgery and complete resection was achieved. Mean operative time was 153.2 minutes (range 115-300 minutes). Mean blood loss during surgery was 110.3 mL (range 50-175 mL). No infection or aggravation of spinal cord injury occurred after operation, except for 2 patients who had postoperative cerebrospinal fluid leakage that recovered after conservative treatment. The mean duration of hospital stay was 6.8 days (range 5-10 days). At the last follow-up, all patients had a reduced level of pain as suggested by an average visual analog scale score that improved from 7.6 to 0.2. The American Spinal Injury Association grade improved or remained normal in all patients except 1. No evidence of tumor recurrence or secondary spinal deformity was observed in any patients during the postoperative follow-up period, and spinal stabilities were found to be satisfactory. Based on our results, the microscopic minimally invasive keyhole technique can be used safely and effectively for resection of thoracic spinal meningiomas.

Refractive, sensory, and biometric outcome among retinopathy of prematurity children with a history of laser therapy: A retrospective review from a tertiary care center in South India.

Purpose:Ocular morbidities like high refractive error, strabismus, and amblyopia are common among laser-treated retinopathy of prematurity children (ROP). Long-term optical status and refractive outcomes including the sensory outcomes were less investigated in these children from this region. The purpose of our study is to evaluate the long-term outcome (refractive, biometric profile, sensory) of treatment for ROP using laser.Methods:This study is a retrospective, cross-sectional, observational, and intervention research among 6–15-year-old children who underwent laser for ROP with a minimum of 6-year follow-up.Results:Eighty lasered eyes of 41 children were assessed. Mean age was 9.71 years (±3.39). Seventy-three eyes (91.2%) achieved visual acuity better than 20/40. The mean visual acuity in LogMAR was 0.18 (20/30). The mean spherical equivalence was −5.29 D ± 4.9. Mean astigmatism measured was −1.53 DC (range: +0.50 DC to −4.5DC). Fifty-three eyes (66.25%) had significant astigmatism. The mean axial length was 23.5 ± 1.35 (21–26) mm. Mean lens thickness was 3.76 ± 0.30 (3.03–4.34) mm. Correlation analysis among the low and high spherical equivalent group signified that axial length (P value = 0.001), visual acuity (P value = 0.0002), and myopic shift (P value = 0.0006) were found to be statistically significant. Stereopsis better than 480 s of arc for near was observed in 41% children. Structural posterior pole sequelae developed in 3 eyes (3.75%).Conclusion:A significant number of children with high myopia, astigmatism, and strabismus had satisfactory visual outcome observed at long-term follow-up after treatment for ROP using laser. Our study revealed that myopia was influenced by an increase in axial length than the lens thickness.

Assessment of Infraorbital Hypesthesia Following Orbital Floor and Zygomaticomaxillary Complex Fractures Using a Novel Sensory Grading System

Introduction of a novel sensory grading system to assess the incidence and long-term recovery of infraorbital hypesthesia following orbital floor and inferior orbital rim fractures. Patients who presented for evaluation of orbital floor and/or zygomaticomaxillary complex (ZMC) fractures between January 2015 and April 2016 were analyzed. Two-point subjective infraorbital sensory grading in 5 discrete anatomic areas was performed. Fractures were repaired based on traditional criteria; hypesthesia was not an indication for surgery. The sensory grading system was repeated a mean 21.7 months (range 18-28) after initial fracture. Sixty-two patients (mean 41.8 years) participated in the initial symptom grading, and 42 patients (67.7%) completed the 2-year follow-up. Overall, 20 of 42 patients (47.6%) had some infraorbital hypesthesia. There were fewer with isolated orbital floor fractures versus ZMC fractures (31.8% vs. 68.4%; p = 0.019). Two years postinjury, 9.1% and 40.0% with isolated floor and ZMC fractures, respectively, had persistent sensory disturbance (p = 0.0188). Of patients with sensory disturbance on presentation, 71.4% with isolated floor fractures and 38.5% with ZMC fractures experienced complete sensory recovery (p = 0.1596). Patients with isolated floor fractures had improved recovery after surgery (100% vs. 33.3% recovery; p = 0.0410). Patients with ZMC fractures showed no difference in sensory prognosis between those repaired and observed. In this pilot study, isolated orbital floor fractures carried a good infraorbital sensory prognosis, further improved by surgical repair. Zygomaticomaxillary complex fractures portended a worse long-term sensory outcome, unaffected by management strategy. This study validates the novel sensory grading system in post-fracture analysis.

Deficient head motor control in functional dizziness: Experimental evidence of central sensory-motor dysfunction in persistent physical symptoms.

Understanding the mechanisms of symptoms that are insufficiently explained by organic dysfunction remains challenging. Recently, it has been proposed that such "functional symptoms" are based on erroneous sensory processing in the central nervous system (CNS), with internal expectations dominating sensory inputs. In a pilot study, we used a head motor control set-up to assess the interplay between sensory input and expectation on the example of patients with functional dizziness. Eight patients and 11 age-matched healthy controls performed large active eye-head gaze shifts towards visual targets in the natural situation and with the head moment of inertia 3.3-fold increased. The latter induces head oscillations and the expected sensory outcome of the movement, estimated in the CNS, does not match the actual sensory input. Head oscillations were assessed in patients and in healthy subjects and compared to prior results from patients with organic disease (vestibular loss and cerebellar ataxia). Head oscillations in patients with functional dizziness were different from those of healthy subjects (F(1,17)=27.26, P<0.001, partial η2=0.62), and similar to those of patients with cerebellar ataxia, and with vestibular loss (F(2,19)=0.56, P=0.58). Even in the natural, unweighted, condition, head oscillations were higher in functional dizziness patients than in healthy subjects (P=0.001). Since an extensive work-up failed to demonstrate any explanatory peripheral vestibular, motor, or cerebellar organic dysfunction, these motor control deficits are a first indication of erroneous interplay between expectations and sensory input in the CNS that could account for persistent physical symptoms.

Beyond Motor Noise: Considering Other Causes of Impaired Reinforcement Learning in Cerebellar Patients.

Motor and reinforcement learning have been classically linked to functionally independent brain networks centered on the cerebellum and the basal ganglia, respectively. In a recent study published in eNeuro , Therrien et al. (2018) showed that increasing motor noise in healthy subjects disrupts reinforcement learning. However, this impairment remained well below that detected in cerebellar patients even when motor noise in healthy subjects was adjusted to match that observed in the patients. This suggests that impaired reinforcement learning following cerebellar damage cannot be solely accounted for by altered motor noise in these patients. Based on recent anatomic and functional evidence, we argue that the cerebellum may directly contribute to reinforcement learning, consistent with its tight connections with the basal ganglia. The ability to adapt to changes occurring in the environment is a fundamental feature of human behavior, which relies on both sensory and reward feedbacks. On the one hand, the role of sensory feedback has been largely considered by studying how motor commands adapt to visual perturbations (e.g., a visuomotor rotation), a process called error-based learning (Shadmehr et al., 2010; Wolpert et al., 2011; Kim et al., 2018; Roemmich and Bastian, 2018). This type of motor learning involves the computation of sensory prediction errors (SPEs), namely, the difference between predicted and actual sensory outcome (Tseng et al., 2007; Schlerf and Ivry, 2012; Shadmehr, 2017, 2018). On the other hand, the role of reward feedback has been mostly investigated in tasks that require learning what action to select or not, by updating reward predictions based on previous experience, a process named reinforcement learning (Lee et al., 2012; Derosiere et al., 2017a,b; Gershman and Daw, 2017; O’Doherty et al., 2017). A central …

Neuroanatomical correlates of sensory deficits in children with neonatal arterial ischemic stroke.

Our aim was to characterize the sensory processing outcome following neonatal arterial ischemic stroke (NAIS) and identify neuroanatomical correlates of abnormal sensory processing. We evaluated children with NAIS longitudinally at 12 months, 18 months, and/or 30 months in areas of cognitive, motor, and language development. We gathered sensory processing data using the Sensory Profile-2 Caregiver Questionnaire. These data were analyzed against early magnetic resonance imaging using a voxel-based approach. Eighteen children (10 males, 8 females) with NAIS were evaluated longitudinally, of which six exhibited atypical sensory processing. Children with sensory processing deficits had lower overall developmental scores in motor, cognitive, and language domains. Neuroanatomical correlates were identified in the posterior periventricular white matter extending superiorly into the supramarginal gyrus, and inferiorly into the fusiform and inferior temporal gyri. Our results provide new evidence that children with NAIS may experience difficulty processing sensory information, which is most likely associated with injuries in the posterior periventricular white matter, supramarginal gyrus, fusiform gyrus, and posterior thalamic radiation. Atypical sensory processing is common in children with neonatal arterial ischemic stroke (NAIS). NAIS territories in sensory areas were correlated with atypical sensory processing behaviors. Children with NAIS may benefit from early interventions targeted toward sensory processing. Future research mapping NAIS injuries using early magnetic resonance imaging may predict long-term outcomes.

Changes in intentional binding effect during a novel perceptual-motor task.

Perceptual-motor learning describes the process of improving the smoothness and accuracy of movements. Intentional binding (IB) is a phenomenon whereby the length of time between performing a voluntary action and the production of a sensory outcome during perceptual-motor control is perceived as being shorter than the reality. How IB may change over the course of perceptual-motor learning, however, has not been explicitly investigated. Here, we developed a set of IB tasks during perceptual-motor learning. Participants were instructed to stop a circular moving object by key press when it reached the center of a target circle on the display screen. The distance between the center of the target circle and the center of the moving object was measured, and the error was used to approximate the perceptual-motor performance index. This task also included an additional exercise that was unrelated to the perceptual-motor task: after pressing the key, a sound was presented after a randomly chosen delay of 200, 500, or 700 ms and the participant had to estimate the delay interval. The difference between the estimated and actual delay was used as the IB value. A cluster analysis was then performed using the error values from the first and last task to group the participants based on their perceptual-motor performance. Participants showing a very small change in error value, and thus demonstrating a small effect of perceptual-motor learning, were classified into cluster 1. Those who exhibited a large decrease in error value from the first to the last set, and thus demonstrated a strong improvement in perceptual-motor performance, were classified into cluster 2. Those who exhibited perceptual-motor learning also showed improvements in the IB value. Our data suggest that IB is elevated when perceptual-motor learning occurs.

Whole-Brain Neuronal Activity Displays Crackling Noise Dynamics

SummaryPrevious studies suggest that the brain operates at a critical point in which phases of order and disorder coexist, producing emergent patterned dynamics at all scales and optimizing several brain functions. Here, we combined light-sheet microscopy with GCaMP zebrafish larvae to study whole-brain dynamics in vivo at near single-cell resolution. We show that spontaneous activity propagates in the brain’s three-dimensional space, generating scale-invariant neuronal avalanches with time courses and recurrence times that exhibit statistical self-similarity at different magnitude, temporal, and frequency scales. This suggests that the nervous system operates close to a non-equilibrium phase transition, where a large repertoire of spatial, temporal, and interactive modes can be supported. Finally, we show that gap junctions contribute to the maintenance of criticality and that, during interactions with the environment (sensory inputs and self-generated behaviors), the system is transiently displaced to a more ordered regime, conceivably to limit the potential sensory representations and motor outcomes.

Task errors contribute to implicit aftereffects in sensorimotor adaptation.

Perturbations of sensory feedback evoke sensory prediction errors (discrepancies between predicted and actual sensory outcomes of movements), and reward prediction errors (discrepancies between predicted rewards and actual rewards). When our task is to hit a target, we expect to succeed in hitting the target, and so we experience a reward prediction error if the perturbation causes us to miss it. These discrepancies between intended task outcomes and actual task outcomes, termed "task errors," are thought to drive the use of strategic processes to restore success, although their role is incompletely understood. Here, as participants adapted to a 30° rotation of cursor feedback representing hand position, we investigated the role of task errors in sensorimotor adaptation: during target-reaching, we either removed task errors by moving the target mid-movement to align with cursor feedback of hand position, or enforced task error by moving the target away from the cursor feedback of hand position, by 20-30° randomly (clockwise in half the trials, counterclockwise in half the trials). Removing task errors not only reduced the extent of adaptation during exposure to the perturbation, but also reduced the amount of post-adaptation aftereffects that persisted despite explicit knowledge of the perturbation removal. Hence, task errors contribute to implicit adaptation resulting from sensory prediction errors. This suggests that the system which predicts the sensory consequences of actions via exposure to sensory prediction errors is also sensitive to reward prediction errors.

Evaluation of accuracy and sensory outcomes of mandibular reconstruction using computer-assisted surgical simulation

PurposeTo introduce a modified protocol for mandibular reconstruction and evaluate the protocol using a standardized assessment method. MethodThis retrospective study involved a case series of nine patients who underwent mandibular reconstruction between 2015 and 2017. The modular protocol comprised three novel modifications in terms of computer-assisted surgical simulation (CASS); surgical template (ST), and surgical procedure. The standardized postoperative evaluation consisted of operation time, part comparison analysis (PCA), facial symmetry, and mechanical quantitative sensory testing. ResultsThe surgery successfully removed the affected mandible and preserved the inferior alveolar neurovascular bundle (IANB). PCA revealed that the mean error and standard deviation were 0.92 and 0.96 mm, respectively, for all mandibular surface sites. Follow-up results showed good facial symmetry, existence of sensation in lower lip, and no significant differences in pulp vitality between both sides (p = 0.181). Also, the results showed a reduction in the overall operating time. ConclusionThe modified mandibular reconstruction method used in this study could repair lateral mandibular defects and preserve the sensory function of the chin and lower lip.

Human posterior parietal and dorsal premotor cortex encode the visual properties of an upcoming action.

Behavioral studies show that motor actions are planned by adapting motor programs to produce desired visual consequences. Does this mean that the brain plans these visual consequences independent of the motor actions required to obtain them? Here we addressed this question by investigating planning-related fMRI activity in human posterior parietal (PPC) and dorsal premotor (PMd) cortex. By manipulating visual movement of a virtual end-effector controlled via button presses we could dissociate motor actions from their sensory outcome. A clear representation of the visual consequences was visible in both PPC and PMd activity during early planning stages. Our findings suggest that in both PPC and PMd action plans are initially represented on the basis of the desired sensory outcomes while later activity shifts towards representing motor programs.

The endless visuomotor calibration of reach-to-grasp actions

It is reasonable to assume that when we grasp an object we carry out the movement based only on the currently available sensory information. Unfortunately, our senses are often prone to err. Here, we show that the visuomotor system exploits the mismatch between the predicted and sensory outcomes of the immediately preceding action (sensory prediction error) to attain a degree of robustness against the fallibility of our perceptual processes. Participants performed reach-to-grasp movements toward objects presented at eye level at various distances. Grip aperture was affected by the object distance, even though both visual feedback of the hand and haptic feedback were provided. Crucially, grip aperture as well as the trajectory of the hand were systematically influenced also by the immediately preceding action. These results are well predicted by a model that modifies an internal state of the visuomotor system by adjusting the visuomotor mapping based on the sensory prediction errors. In sum, the visuomotor system appears to be in a constant fine-tuning process which makes the generation and control of grasping movements more resistant to interferences caused by our perceptual errors.

Lateral Lumbar Interbody Fusion Revisited: Complication Avoidance and Outcomes with the Mini-Open Approach

To discuss lessons learned from an initial lateral lumbar interbody fusion (LLIF) experience with a focus on evolving surgical technique, complication avoidance, and new motor and sensory outcomes after implementation of a modified surgical approach. A retrospective analysis of a prospectively collected series of all patients undergoing LLIF by the senior author (A.D.L.) from January 2010 to January 2018 after implementation of a modified surgical mini-open technique, compared with previously reported institutional results with the originally recommended percutaneous technique. LLIF-specific complications examined included groin/thigh sensory dysfunction, flank bulge/pseudohernia, psoas-pattern weakness, and femoral nerve injury. The incidence (19%, n= 98 patients) of groin/thigh sensory dysfunction in our cohort was significantly lower than that of the historical control (60%, n= 59) (P<0.0001). The incidence of abdominal flank bulge/pseudohernia (2.0%, n= 98 patients) in our cohort was improved but not significantly lower than that of the historical control (4.2%, n= 118) (P= 0.36). The incidence of psoas-pattern weakness (3.1%, n= 98) in our cohort was significantly lower than that of the historical control (23.7%, n= 59) (P= 0.0001). The incidence of femoral nerve injury (0%, n= 98 patients) in our cohort was improved but was not significantly lower than that of the historical control (1.7%, n= 118) (P= 0.20). The adoption of an exclusive mini-open muscle-splitting approach with first-look inspection of the lumbosacral plexus nerve elements may improve motor and sensory outcomes in general and the incidence of postoperative groin/thigh sensory dysfunction and psoas-pattern weakness in particular.

The Helsinki approach to face transplantation

AimWe herein describe the establishment of the Helsinki Vascularized Composite Allotransplantation (VCA) program and its execution in the first two face transplant cases. Methods & patientsThe Helsinki VCA program initially required the fulfillment of legal, hospital, financial, and ethical requirements. Thereafter, the assembling of a multidisciplinary team commenced. A team of Plastic, maxillofacial and ENT surgeons comprise the facial VCA team. The protocol involves collaboration with the Solid Organ Transplant (SOT) team, transplant immunology, immunosuppression, microbiology, psychiatric evaluation, well-defined VCA indications and informed consent. Between 2011 and 2017 two patients were selected for transplantation. Both patients had a severe composite facial deformity involving the maxilla and mandible following earlier ballistic injury. ResultsPatient 1 was a 35 year-old male who underwent successful near total face transplantation in February 2016 and at 30 months he has a good aesthetic outcome with symmetrical restoration of the central face and good sensory and symmetrical motor functional outcomes. Patient 2 was a 58 year-old male who underwent full face transplantation in March 2018 and at 5 months he has recovered without major problems. ConclusionA successful facial VCA program requires a well-prepared research protocol, experts from multiple specialties and careful patient selection. The establishment of the Helsinki VCA program required long and thorough planning and resulted in the first two Nordic face transplantation cases. This protocol now forms the platform (as a proof of concept) for other types of vascularized composite allotransplantations.

Robust Sensorimotor Learning during Variable Sentence-Level Speech

Sensorimotor learning has been studied by altering the sound of the voice in real time as speech is produced. In response to voice alterations, learned changes in production reduce the perceived auditory error and persist for some time after the alteration is removed [1-5]. The results of such experiments have led to the development of prominent models of speech production. This work proposes that the control of speech relies on forward models to predict sensory outcomes of movements, and errors in these predictions drive sensorimotor learning [5-7]. However, sensorimotor learning in speech has only been observed following intensive training on ahandful of discrete words or perceptually similar sentences. Stereotyped production does not capture the complex sensorimotor demands of fluid, real-world speech [8-11]. It remains unknown whether talkers predict the sensory consequences of variable sentence production to allow rapid and precise updating of speech motor plans when sensory prediction errors are encountered. Here, we used real-time alterations of speech feedback to test for sensorimotor learning during the production of 50 sentences that varied markedly in length, vocabulary, and grammar. Following baseline production, all vowels were simultaneously altered and played back through headphones in near real time. Robust feedforward changes in sentence production were observed that, on average, precisely countered the direction of the alteration. These changes occurred in every participant and transferred to the production of single words with varying vowel sounds. The results show that to maintain accurate sentence production, the brain actively predicts the auditory consequences of variable sentence-level speech.

Long-term motor and sensory outcomes after surgery for the nonaccommodative component of partially refractive accommodative esotropia

To report long-term motor and sensory outcomes after surgery for the nonaccommodative component of partially refractive accommodative esotropia (PRAET). The medical records of consecutive patients ≤11years old operated for the nonaccommodative component of PRAET and followed postoperatively for at least 10years were retrospectively reviewed. A total of 47 patients were included (median age, 3.0years). The mean postoperative follow-up was 12.15±2.05years (range, 10.00-17.50years). Overall, 23 patients (49%) had surgical success; 10 (21%), decompensation; and 7 (15%), esotropia with a high ratio of accommodative convergence to accommodation (AC/A) or consecutive exotropia. The median age at surgery, mean cycloplegic refraction, median near and distance deviation, presence of binocular vision, and amblyopia did not predict decompensation, a high AC/A ratio esotropia, and consecutive exotropia. Eight patients (18%) achieved stereopsis. Patients with an older age at onset (2.87±1.31years) and a shorter duration of strabismus (≤4years) achieved better stereopsis. Nearly half of our patients with PRAET achieved a successful ocular alignment after surgery for the nonaccommodative component. Some developed decompensation, a high AC/A ratio esotropia, or consecutive exotropia. Few patients achieved stereopsis. Older age at onset and a shorter duration of strabismus predicted a better stereopsis outcome.

Loss of Type A neuronal cells in the dorsal root ganglion after a non-severe full-thickness burn injury in a rodent model

Burn scars can be associated with significant loss of cutaneous sensation, paresthesia and chronic pain. Long-term systemic changes in cutaneous innervation may contribute to these symptoms and dorsal root ganglia have been implicated in the development of chronic neuropathic pain. Therefore we hypothesized that changes in cutaneous innervation after burn injury may be mediated at the level of the dorsal root ganglia. Burn group rats (n=20) were subjected to a unilateral burn injury while 12 control rats underwent sham procedure. The DRGs dermatomally related to the site of burn (Thoracic 13, lumbar 1 and lumbar 2), ipsilateral and contralateral to the injury, were compared for Type A, Type B and total cell number with sham control DRGs, at 4 and 6 weeks after injury. There was a significant decrease in Type A cell count (cell bodies of nerve fibres mediating touch-pressure-vibration sensation) in the 4 week time-point group (p=0.0124) ipsilateral to the burn injury. Total DRG cell count and Type B DRG cell count (cell bodies of fibres mediating pain and itch) on the ipsilateral side was not significantly altered. On the side contralateral to the burn injury, there was no statistically significant change in the total cell count, Type A cell count or Type B cell count. This data showed a decrease in Type A cell number in DRGs after a burn injury, suggesting cell death may mediate some changes observed in cutaneous innervation after a burn. Type B cells constituted a greater proportion of the viable cell population in the ipsilateral DRG after a burn injury. This change may be important in the induction of signalling related to pain and itch and has important implications for the restoration of normal cutaneous innervation after burn injury. Investigating whether neuro-protective or neuro-restorative approaches can ameliorate damage to the DRG will be important to improve sensory outcomes for burn patients.