Video head impulse testing to differentiate vestibular neuritis from posterior circulation stroke in the emergency department: a prospective observational study.

Background and aims: Vertigo is a common presentation to the emergency department (ED) with 5% of presentations due to posterior circulation stroke (PCS). Bedside investigations such as the head impulse test (HIT) are used to risk stratify patients, but interpretation is operator dependent. The video HIT (v-HIT) provides objective measurement of the vestibular-ocular-reflex (VOR) and may improve diagnostic accuracy in acute vestibular syndrome (AVS). We aimed to evaluate the use of v-HIT as an adjunct to clinical assessment to acutely differentiate vestibular neuritis (VN) from PCS. Methods: 133 patients with AVS were consecutively enrolled from the ED of our comprehensive stroke centre between 2018 and 2021. Patient assessment included a targeted vestibular history, HINTs examination (Head Impulse, Nystagmus and Test of Skew), v-HIT and MRI>48 hours after symptom onset. The HINTS/v-HIT findings were analysed and compared between VN, PCS and other cause AVS. Clinical course, v-HIT and MRI findings were used to determine diagnosis. Results: Final diagnosis was VN in 40%, PCS 15%, migraine 16% and other cause AVS 29%. PCS patients were older than VN patients (mean age 68.5±10.6 vs 60.1±14.2 years, p=0.14) and had more cardiovascular risk factors (3 vs 2, p=0.002). Mean VOR gain was reduced (<0.8) in ipsilateral horizontal and (<0.7) anterior canals in VN but was normal in PCS, migraine and other cause AVS. V-HIT combined with HINTs was 89% sensitive and 96% specific for a diagnosis of VN. Conclusions V-HIT combined with HINTs is a reliable tool to exclude PCS in the ED.

Evidence that increased cholecystokinin (CCK) in the periaqueductal gray (PAG) facilitates changes in Resident-Intruder social interactions triggered by peripheral nerve injury.

Individual differences in the effects of a chronic neuropathic injury on social behaviours characterize both the human experience and pre-clinical animal models. The impacts of these changes to the well-being of the individual are often underappreciated. Earlier work from our laboratory using GeneChip® microarrays identified increased cholecystokinin (CCK) gene expression in the periaqueductal gray (PAG) of rats that showed persistent changes in social interactions during a Resident-Intruder encounter following sciatic nerve chronic constriction injury (CCI). In this study, we confirmed these gene regulation patterns using RT-PCR and identified the anatomical location of the CCK-mRNA as well as the translated CCK peptides in the midbrains of rats with a CCI. We found that rats with persistent CCI-induced changes in social behaviours had increased CCK-mRNA in neurons of the ventrolateral PAG and dorsal raphe nuclei, as well as increased CCK-8 peptide expression in terminal boutons located in the lateral and ventrolateral PAG. The functional significance of these changes was explored by microinjecting small volumes of CCK-8 into the PAG of uninjured rats and observing their Resident-Intruder social interactions. Disturbances to social interactions identical to those observed in CCI rats were evoked when injection sites were located in the rostral lateral and ventrolateral PAG. We suggest that CCI-induced changes in CCK expression in these PAG regions contributes to the disruptions to social behaviours experienced by a subset of individuals with neuropathic injury.

Recruitment of dorsal midbrain catecholaminergic pathways in the recovery from nerve injury evoked disabilities.

BACKGROUND: The periaqueductal gray region (PAG) is one of several brain areas identified to be vulnerable to structural and functional change following peripheral nerve injury. Sciatic nerve constriction injury (CCI) triggers neuropathic pain and three distinct profiles of changes in complex behaviours, which include altered social and sleep-wake behaviours as well as changes in endocrine function. The PAG encompasses subgroups of the A10 dopaminergic and A6 noradrenergic cell groups; the origins of significant ascending projections to hypothalamic and forebrain regions, which regulate sleep, complex behaviours and endocrine function. We used RT-PCR, western blots and immunohistochemistry for tyrosine hydroxylase to determine whether (1) tyrosine hydroxylase increased in the A10/A6 cells and/or; (2) de novo synthesis of tyrosine hydroxylase, in a 'TH-naïve' population of ventral PAG neurons characterized rats with distinct patterns of behavioural and endocrine change co-morbid with CCI evoked-pain. RESULTS: Evidence for increased tyrosine hydroxylase transcription and translation in the constitutive A10/A6 cells was found in the midbrain of rats that showed an initial 2-3 day post-CCI, behavioural and endocrine change, which recovered by days 5-6 post-CCI. Furthermore these rats showed significant increases in the density of TH-IR fibres in the vPAG. CONCLUSIONS: Our data provide evidence for: (1) potential increases in dopamine and noradrenaline synthesis in vPAG cells; and (2) increased catecholaminergic drive on vPAG neurons in rats in which transient changes in social behavior are seen following CCI. The data suggests a role for dopaminergic and noradrenergic outputs, and catecholaminergic inputs of the vPAG in the expression of one of the profiles of behavioural and endocrine change triggered by nerve injury.

Time for a change in injury and trauma care delivery: a trauma death review analysis.

Safety and error reduction in medical care is crucial to the future of medicine. This study evaluates trauma patients dying at a level 1 trauma centre to determine the adequacy of care. All trauma deaths at a level 1 trauma centre between 1996 and 2003 were reviewed by an eight-member multidisciplinary death review panel. Errors in care were classified according to their location, nature, impact, outcome and whether the deaths were avoidable or non-avoidable. Avoidable deaths were categorized as potentially, probably and definitely avoidable. Between 1996 and 2003, there were 17 157 trauma admissions, including 307 trauma deaths. The mean patient age was 47.7 years +/- 24.8 years, mean injury severity score 38.1 +/- 19.6. Of all deaths, 69 (22.5%) were deemed avoidable. Of the avoidable deaths, 61 (88%) were potentially avoidable, 7 (10%) probably avoidable and 1 (1.4%) definitely avoidable. Avoidable deaths were associated with patients with increased age, lower injury severity score, admissions to intensive care unit, longer hospital stay and treatment by a non-trauma surgeon (P < 0.05). Of the 307 trauma deaths, 271 (89.3%) patients experienced a total of 1063 errors, an overall error rate of 3.5 per patient. The error rate in the non-avoidable group was 2.9 per patient and 5.3 per patient in the avoidable group (P < 0.0001). Most errors occurred in the resuscitation area. Age, severity of injury, hospital length of stay and care by a non-trauma surgeon are factors associated with avoidable deaths. A new approach to trauma and injury care is required.