Benjamin I. Silbert

Peer-assisted learning in teaching clinical examination to junior medical students

Background: In medical education, peer-assisted learning (PAL) refers to teaching occurring between fellow students. Few descriptions of its use to teach clinical examination have been published. Student Grand Rounds (SGR) is a student-led initiative whereby senior students volunteer to teach clinical examination to pre-clinical peers. Student tutors attend a modified Teaching on the Run (TOTR) course originally designed to train clinicians to teach students and junior doctors. Aim: We investigated the value of SGR in teaching pre-clinical students, and evaluated the effectiveness of TOTR. Methods: Over 9 months, tutors and participants in each SGR tutorial completed an online survey. At the conclusion of annual TOTR workshops (2004–2010), participants evaluated their impressions of the course. Results: A total of 64 SGR tutorials were attended by a total of 321 students. All agreed that tutorials were beneficial and enjoyable, with a threefold increase in the number of students self-identifying as able to perform the skills required. TOTR participants classified the course as both relevant and beneficial, and all course outcomes were achieved. SGR tutors reported improved knowledge and confidence in teaching following SGR and TOTR. Conclusion: PAL is effective in supplementing teaching of clinical examination. Senior students learn valuable skills and gain experience in teaching.

Inverse Correlation Between Resting Motor Threshold and Corticomotor Excitability After Static Magnetic Stimulation of Human Motor Cortex

BACKGROUND High-strength static magnetic field stimulation (SMS) results in a period of reduced corticomotor excitability that may be mediated through a decrease in membrane excitability. OBJECTIVE As resting motor threshold (RMT) is thought to reflect membrane excitability, we hypothesized that SMS may increase RMT and that there would be an inverse relationship between RMT and motor-evoked potential (MEP) amplitude. METHODS Ten healthy subjects (aged 20-29; 4 females) participated in a double-blinded crossover design comparing MEP amplitude and RMT before and after a 15-min period of SMS or sham stimulation over primary motor cortex (M1). RESULTS MEP amplitude was initially significantly reduced post-SMS (∼20%), and returned to baseline by 6 min post-intervention. MEP amplitude and RMT were inversely correlated (r(2) = 0.924; P = 0.001). Sham stimulation had no effect on MEP amplitude (P = 0.969) or RMT (P = 0.549). CONCLUSION After SMS, corticomotor excitability is transiently reduced in association with a correlated modulation of RMT. SMS after effects may be mediated in part by a reduction in membrane excitability, suggesting a possible role for non-synaptic (intrinsic) plasticity mechanisms.

A comparison of relative-frequency and threshold-hunting methods to determine stimulus intensity in transcranial magnetic stimulation

OBJECTIVE Stimulation intensity (SI) in transcranial magnetic stimulation is commonly set in relation to motor threshold (MT), or to achieve a motor-evoked potential (MEP) of predefined amplitude (usually 1 mV). Recently, IFCN recommended adaptive threshold-hunting over the previously endorsed relative-frequency method. We compared the Rossini-Rothwell (R-R) relative-frequency method to an adaptive threshold-hunting method based on parameter estimation by sequential testing (PEST) for determining MT and the SI to target a MEP amplitude of 1 mV (I(1) mV). METHODS In 10 healthy controls we determined MT and I(1) mV with R-R and PEST using a blinded crossover design, and performed within-session serial PEST measurements of MT. RESULTS There was no significant difference between methods for MT (52.6±2.6% vs. 53.7±3.1%; p=0.302; % maximum stimulator output; R-R vs. PEST, respectively) or I(1) mV (66.7±3.0% vs. 68.8±3.8%; p=0.146). There was strong correlation between R-R and PEST estimates for both MT and I(1) mV. R-R required significantly more stimuli than PEST. Serial measurements of MT with PEST were reproducible. CONCLUSIONS PEST has the advantage of speed without sacrificing precision when compared to the R-R method, and is adaptable to other SI targets. SIGNIFICANCE Our results in healthy controls add to increasing evidence in favour of adaptive threshold-hunting methods for determining SI.

Students as teachers

doi: 10.5694/mja12.10970 F ew would challenge the assertion that senior doctors play a vital role in teaching and supervising peers, junior colleagues and students. Junior doctor teaching of medical students is also signifi cant, and students estimate that up to one-third of their knowledge can be attributed to junior doctors.1 Effective teaching is a learned skill; teaching workshops develop and refi ne teaching skills, improve attitudes towards teaching and may introduce new teaching tools.2 Such “faculty” development, although more available these days, still remains optional for many, and particularly for junior doctors, learning such skills may compete with patient care responsibilities and specialty training.1 We believe Australian medical schools should strongly consider implementing a comprehensive, vertically integrated student teaching program employing peerassisted learning (PAL). PAL refers to “people from similar social groupings who are not professional teachers helping each other to learn and learning themselves by teaching” .3 Through PAL, students learn how to teach and give feedback, and under supervision are given the chance to practise and consolidate these skills. It has been used successfully to teach theoretical information, as well as procedural and clinical examination skills to medical students in small group settings.4,5 Although most evidence is based on predominantly extracurricular programs in American and European medical schools, an extracurricular program at the University of Western Australia (UWA) has recently been described with similar fi ndings.6 Recent publications offer detailed discussions of many issues related to the implementation of PAL.4,7 A number of practicalities deserve special consideration in the Australian context, and in this paper we offer recommendations on how these issues might be approached.

Evidence for an excitatory GABAA response in human motor cortex in idiopathic generalised epilepsy

PURPOSE Impaired GABAergic inhibition has been implicated in the pathophysiology of epilepsy. The possibility of a paradoxical excitatory effect of GABA in epilepsy has been suggested, but has not been investigated in vivo. We investigated pre- and post-synaptic GABAergic mechanisms in patients with idiopathic generalised epilepsy (IGE). METHOD In 10 patients and 12 control subjects we explored short- and long-interval intracortical inhibition (SICI, LICI; post-synaptic GABAA and GABAB-mediated respectively) and long-interval intracortical facilitation (LICF; pre-synaptic disinhibition) using transcranial magnetic stimulation. RESULTS While post-synaptic GABAB-mediated inhibition was unchanged in IGE (p=0.09), LICF was reduced compared to controls (controls: 141±17% of baseline; untreated patients: 107±12%, p=0.2; treated patients: 79±10%, p=0.003). GABAA-mediated inhibition was reduced in untreated patients (response amplitude 56±4% of baseline vs. 26±6% in controls, p=0.004) and normalised with treatment (37±12%, p=0.5 vs. controls). When measured during LICI, GABAA-mediated inhibition became excitatory in untreated IGE (response amplitude 120±10% of baseline, p=0.017), but not in treated patients. CONCLUSION Pre- and post-synaptic GABA-mediated inhibitory mechanisms are altered in IGE. The findings lend in vivo support to evidence from experimental models and in vitro studies of human epileptic brain tissue that GABA may have a paradoxical excitatory role in ictogenesis.

The Role of Botulinum Toxin Type A in the Clinical Management of Refractory Anterior Knee Pain

Anterior knee pain is a highly prevalent condition affecting largely young to middle aged adults. Symptoms can recur in more than two thirds of cases, often resulting in activity limitation and reduced participation in employment and recreational pursuits. Persistent anterior knee pain is difficult to treat and many individuals eventually consider a surgical intervention. Evidence for long term benefit of most conservative treatments or surgical approaches is currently lacking. Injection of Botulinum toxin type A to the distal region of vastus lateralis muscle causes a short term functional “denervation” which moderates the influence of vastus lateralis muscle on the knee extensor mechanism and increases the relative contribution of the vastus medialis muscle. Initial data suggest that, compared with other interventions for anterior knee pain, Botulinum toxin type A injection, in combination with an active exercise programme, can lead to sustained relief of symptoms, reduced health care utilisation and increased activity participation. The procedure is less invasive than surgical intervention, relatively easy to perform, and is time- and cost-effective. Further studies, including larger randomized placebo-controlled trials, are required to confirm the effectiveness of Botulinum toxin type A injection for anterior knee pain and to elaborate the possible mechanisms underpinning pain and symptom relief.

Enduring efficacy of Botulinum toxin type A injection for refractory anterior knee pain

Purpose: To examine long-term outcomes of Botulinum toxin type A (BoNT-A) injection to vastus lateralis (VL) for refractory anterior knee pain (AKP). Methods: Two cohorts (private clinic referrals and previous research participants) injected with BoNT-A for AKP by one neurologist were surveyed retrospectively. Primary outcomes were self-reported benefit, duration of symptom relief, and knee surgery post-injection. Secondary outcomes were changes in utilization of medication/physiotherapy treatment, AKP symptoms and activity limitation. Results: Overall, average symptom duration was 76 months (SD 98). Responses were available from 46 of 53 private patients. Thirty-eight reported benefit from injection, which was ongoing in 29. Average benefit was 25 months (SD 21). Nine individuals reported symptom recurrence after an average of 14 months (SD 21). Ten had knee surgery post-injection; six of whom had not benefitted from BoNT-A injection. Nineteen of 23 previous research participants were contactable. Initially, all responded favorably to injection. Symptomatic benefit, with an average duration of 44 months (SD 20), persisted in 15. Two subjects proceeded to surgical intervention. Conclusions: A single BoNT-A treatment to VL led initially to improved function and relief of knee-related symptoms in 57 of 65 individuals. Improvements were sustained at follow-up, with an average benefit of 34 months (SD 25) post-injection, in 44 of 57 cases. Implications for Rehabilitation Persistent anterior knee pain (AKP) can be difficult to treat and many individuals seek surgical intervention, often with variable results. Injection of Botulinum toxin type A (BoNT-A) to Vastus Lateralis muscle offers an effective alternative treatment for individuals with refractory AKP associated with patella mal-tracking related to quadriceps muscle imbalance. BoNT-A injection can provide sustained benefit, is less invasive than surgical intervention, is relatively easy to perform, and is very time- and cost-effective.