A 6-year retrospective review of injuries sustained during the Singapore Cricket Club International Rugby Sevens tournament.

There are limited studies looking at injury statistics for Rugby Sevens. This study aims to assess injury patterns among amateur players participating in the annual Singapore Cricket Club Rugby Sevens International tournament from 2012 to 2017, by performing a retrospective review of their injury data. Outcome measures include injury incidence rate, injury site, and comparative injury incidence between successive days of competition. A total of 343 injuries were recorded over 6 tournaments, with an injury incidence of 348.0 per 1000 player hours. The lower limb was the most commonly injured site (45.8%), and there was greater incidence of injuries on day 3 of competition compared to day 1 in 2013 and 2016. This study reports a higher level of background risk to Rugby Sevens than is reported in literature. A well designed-prospective injury surveillance study will be necessary to confirm these findings and to investigate risk factors to guide injury prevention programmes.

Pilot single-centre cross-sectional study to determine emergency physicians' knowledge and management of sports concussion: an experience from Singapore.

INTRODUCTION: Sports concussion remains challenging to manage despite changes to policy and practice since the 2012 International Consensus Conference on Concussion in Sport. Emergency physicians (EPs) are usually the first line of medical care for athletes in amateur and youth collision sports. This single-centre cross-sectional study aimed to establish EPs' understanding and management of concussion in Singapore. METHODS: An anonymised, 17-item online questionnaire was sent to EPs requesting for information on their clinical experience, training, exposure to concussion cases in the emergency department (ED) and assessed knowledge of the condition. RESULTS: Out of 65 EPs, 52 (80%) responded, 25 (48.1%) of whom were medical officers. Over 90% had not received formal training in concussion management, and 73.1% regularly assessed concussion. 40 (76.9%) EPs recognised that loss of consciousness was not essential for diagnosis and only 24 (46.2%) knew the most common symptom. 26 (50.0%) incorrectly reported that they would perform brain imaging. Among those who indicated onward referral, 29 (55.8%) would refer concussed patients to neurosurgery. There were no significant differences between clinical grade or training in concussion and positive responses for definition, imaging modality or most common symptom of concussion. CONCLUSION: Concussion is a common presentation to EDs in Singapore. However, understanding of the condition, its clinical diagnosis, investigation and onward management is limited. Although EPs reported training in concussion, it is likely to be insufficient. Commencing relevant education programmes for undergraduate and postgraduate medical students may enable progressive acquisition of knowledge and thereby improve patient management in the future.

The functional equivalence of ascending and parallel fiber inputs in cerebellar computation.

At the center of the computational cerebellar circuitry are Purkinje cells, which integrate synaptic inputs from >150,000 granule cell inputs. Traditional theories of cerebellar function assume that all granule cell inputs are comparable. However, it has recently been suggested that the two anatomically distinct granule cell inputs, ascending and parallel fiber, have different functional roles. By systematically examining the efficacy of patches of granule cells with photostimulation, we found no differences in the efficacy of the two inputs in driving the activity of, or in producing postsynaptic currents in, Purkinje cells in cerebellar slices in vitro. We also found that the activity of Purkinje cells was significantly increased upon stimulation of lateral granule cells in vivo. Moreover, when we estimated parallel fiber and ascending apparent unitary EPSC amplitudes using photostimulation in cerebellar slices in vitro, we found them to be indistinguishable. These results are inconsistent with differential functional roles for these two inputs. Instead, our data support theories of cerebellar computation that consider granule cell inputs to be functionally comparable.

The advantages of linear information processing for cerebellar computation.

Purkinje cells can encode the strength of parallel fiber inputs in their firing by using 2 fundamentally different mechanisms, either as pauses or as linear increases in firing rate. It is not clear which of these 2 encoding mechanisms is used by the cerebellum. We used the pattern-recognition capacity of Purkinje cells based on the Marr-Albus-Ito theory of cerebellar learning to evaluate the suitability of the linear algorithm for cerebellar information processing. Here, we demonstrate the simplicity and versatility of pattern recognition in Purkinje cells linearly encoding the strength of parallel fiber inputs in their firing rate. In contrast to encoding patterns with pauses, Purkinje cells using the linear algorithm could recognize a large number of both synchronous and asynchronous input patterns in the presence or absence of inhibitory synaptic transmission. Under all conditions, the number of patterns recognized by Purkinje cells using the linear algorithm was greater than that achieved by encoding information in pauses. Linear encoding of information also allows neurons of deep cerebellar nuclei to use a simple averaging mechanism to significantly increase the computational capacity of the cerebellum. We propose that the virtues of the linear encoding mechanism make it well suited for cerebellar computation.

Questioning the role of rebound firing in the cerebellum.

A key component of recent theories on cerebellar function is rebound firing in neurons of the deep cerebellar nuclei (DCN). Despite the robustness of this phenomenon in vitro, in vivo studies have provided little evidence for its prevalence. We found that intact mouse or rat DCN neurons rarely showed rebound firing under physiological conditions in vitro or in vivo. These observations necessitate a critical re-evaluation of recent cerebellar models.

Ultrasound guided dry needling and autologous blood injection for patellar tendinosis.

OBJECTIVE: To evaluate the efficacy of ultrasound guided dry needling and autologous blood injection for the treatment of patellar tendinosis. DESIGN: Prospective cohort study. SETTING: Hospital/clinic based. PATIENTS: 47 knees in 44 patients (40 men, 7 women, mean age 34.5 years, age range 17 to 54 years) with refractory tendinosis underwent sonographic examination of the patellar tendon following referral with a clinical diagnosis of patellar tendinosis (mean symptom duration 12.9 months). INTERVENTIONS: Ultrasound guided dry needling and injection of autologous blood into the site of patellar tendinosis was performed on two occasions four weeks apart. MAIN OUTCOME MEASURES: Pre- and post-procedure Victorian Institute of Sport Assessment scores (VISA) were collected to assess patient response to treatment. Follow up ultrasound examination was done in 21 patients (22 knees). RESULTS: Therapeutic intervention led to a significant improvement in VISA score: mean pre-procedure score = 39.8 (range 8 to 72) v mean post procedure score = 74.3 (range 29 to 100), p<0.001; mean follow up 14.8 months (range 6 to 22 months). Patients were able to return to their sporting interests. Follow up sonographic assessment showed a reduction in overall tendon thickness and in the size of the area of tendinosis (hypoechoic/anechoic areas within the proximal patellar tendon). A reduction was identified in interstitial tears within the tendon substance. Neovascularity did not reduce significantly or even increased. CONCLUSIONS: Dry needling and autologous blood injection under ultrasound guidance shows promise as a treatment for patients with patellar tendinosis.

The linear computational algorithm of cerebellar Purkinje cells.

The orchestration of simple motor tasks by the cerebellum results in coordinated movement and the maintenance of balance. The cerebellum integrates sensory and cortical information to generate the signals required for the coordinated execution of simple motor tasks. These signals originate in the firing rate of Purkinje cells, each of which integrates sensory and cortical information conveyed by granule cell synaptic inputs. Given the importance of the granule cell input-Purkinje cell output function for cerebellar computation, this algorithm was determined. Using several stimulation paradigms, including those that mimicked patterns of granule cell activity similar to those observed in vivo, we quantified the poststimulus maximum firing rate and number of extra spikes in response to granule cell synaptic input. Both of these parameters linearly encoded the strength of synaptic input when inhibitory synaptic transmission was blocked. This linear algorithm was independent of the location or temporal pattern of synaptic input. With inhibitory synaptic transmission intact, the maximum firing rate, but not the number of extra spikes, encoded the strength of granule cell synaptic input. Furthermore, the maximum firing rate of Purkinje cells linearly encoded the strength of synaptic input whether or not the activation of granule cells resulted in a pause in Purkinje cell firing. On the basis of the data presented, we propose that Purkinje cells encode the strength of granule cell synaptic input in their maximum firing rate with a linear algorithm.

Decreases in the precision of Purkinje cell pacemaking cause cerebellar dysfunction and ataxia.

Episodic ataxia type-2 (EA2) is caused by mutations in P/Q-type voltage-gated calcium channels that are expressed at high densities in cerebellar Purkinje cells. Because P/Q channels support neurotransmitter release at many synapses, it is believed that ataxia is caused by impaired synaptic transmission. Here we show that in ataxic P/Q channel mutant mice, the precision of Purkinje cell pacemaking is lost such that there is a significant degradation of the synaptic information encoded in their activity. The irregular pacemaking is caused by reduced activation of calcium-activated potassium (K(Ca)) channels and was reversed by pharmacologically increasing their activity with 1-ethyl-2-benzimidazolinone (EBIO). Moreover, chronic in vivo perfusion of EBIO into the cerebellum of ataxic mice significantly improved motor performance. Our data support the hypothesis that the precision of intrinsic pacemaking in Purkinje cells is essential for motor coordination and suggest that K(Ca) channels may constitute a potential therapeutic target in EA2.

Kv1 channels selectively prevent dendritic hyperexcitability in rat Purkinje cells.

Purkinje cells, the sole output of the cerebellar cortex, encode the timing signals required for motor coordination in their firing rate and activity pattern. Dendrites of Purkinje cells express a high density of P/Q-type voltage-gated calcium channels and fire dendritic calcium spikes. Here we show that dendritic subthreshold Kv1.2 subunit-containing Kv1 potassium channels prevent generation of random spontaneous calcium spikes. With Kv1 channels blocked, dendritic calcium spikes drive bursts of somatic sodium spikes and prevent the cell from faithfully encoding motor timing signals. The selective dendritic function of Kv1 channels in Purkinje cells allows them to effectively suppress dendritic hyperexcitability without hindering the generation of somatic action potentials. Further, we show that Kv1 channels also contribute to dendritic integration of parallel fibre synaptic input. Kv1 channels are often targeted to soma and axon and the data presented support a major dendritic function for these channels.