Chloe Dafkin

The accuracy of subjective clinical assessments of the patellar reflex.

Introduction: Measurement precision and accuracy of spinal reflexes plays an essential role in the clinical neurological examination. Reflexes are conventionally assessed either electromyographically or with rating scales. In this study we compared objective kinematic T‐reflex and subjective assessments of patellar reflexes in 15 normal healthy subjects. Methods: Randomized recordings of objectively quantified reflexes were rated by 24 medical students, 16 general practitioners, and 12 neurologists, using a visual analog scale and the NINDS and Mayo clinical reflex scales. Results: For all groups of raters, Spearman rank correlations showed that subjective ratings significantly correlated with change of knee angle (R2 = 0.72–0.79, P < 0.001) and maximum T‐reflex amplitude (R2 = 0.84–0.94, P < 0.001). Stepwise multiple regression analysis showed that all subjective rater groups relied most on the change of knee angle to assess the reflex. Conclusions: These findings show that subjective assessments of reflexes using reflex rating scales correlate strongly with biomechanical and electromyographic measures. Muscle Nerve, 2013

Kinematic and kinetic analysis of the inter- and intra-applicator assessment of the Babinski reflex

AIMS OF THE STUDY The first aim was to quantify variability in the mechanical technique used by neurologists to elicit the Babinski reflex. The second aim of the study was to assess if the mechanical technique is an important determinant of the subsequent reflex response. MATERIALS AND METHODS In this study, twelve neurologists elicited the Babinski reflex five times on the same foot of the same participant using a special reflex hammer which recorded the force and duration of the stroke. Hallux movement, tibialis anterior maximum EMG amplitude and pain felt by the participant for each stroke were recorded. RESULTS A large inter- and intra-applicator variability was shown amongst the neurologists. The change in hallux angle was significantly correlated with the duration of the stroke (R(2)=0.18, P<0.01), maximum (R(2)=0.14, P=0.01) and average (R(2)=0.17, P<0.01) force used to elicit the reflex. No correlations were shown between the hammer forces and duration and the maximum amplitude of the tibialis anterior. Significant correlations were shown between the pain score and the maximum (R(2)=0.15, P<0.01) and average (R(2)=0.17, P=0.001) force used to elicit the Babinski reflex. CONCLUSION These results indicate that there was substantial variation when performing the Babinski reflex test within and between neurologists which could lead to differences in the resultant reflex and therefore may affect subsequent diagnoses.

The patellar reflex: does activity of quadriceps femoris muscles reflect leg movement?

Abstract Objectives: The assessment of spinal reflexes has traditionally been performed by clinicians with minimal need for recording equipment, where doctors rely on their training and may use established subjective reflex rating scales. With advances in technology, it is now possible to assess reflexes objectively. This study compared two objective methods of assessing patellar reflex magnitude, duration, and latency, namely electromyography (EMG) of the quadriceps muscles and kinematic assessment of the leg movement around the knee joint. Methods: Reflexes of 24 healthy participants were assessed and seven variables were found to describe each reflex. These were the change in knee angle, the velocity of the reflex, the time to maximum knee angle, the biomechanical movement latency, the EMG maximum amplitude, the negative peak duration, and the EMG latency. Spearman’s rank correlation tests were run in order to compare all of the variables. Results: The results showed that there were positive correlations between EMG maximum amplitude and the change in knee angle (R2 = 0·75; P<0·0001) as well as the EMG maximum amplitude and the velocity of the reflex (R2 = 0·30; P = 0·0058). There was also a negative correlation between EMG maximum amplitude and the biomechanical movement latency (R2 = 0·35; P = 0·0024). Discussion: The results show that there is a relationship between muscle activity and the actual visual movement of the leg assessed using kinematics. This relationship is closest between kinematic measurements and EMG measures of reflex amplitude.

Combined individual scrummaging kinetics and muscular power predict competitive team scrum success

Abstract Scrummaging is a major component of Rugby Union gameplay. Successful scrummaging is dependent on the coordination of the forward players and the strength of the eight individuals. The study aim was to determine whether individual scrummaging kinetics and other candidate factors associated with scrummaging performance discriminate team scrum performances. Sixteen club-level forwards (stature: 1.80 ± 0.1 m; mass: 99.0 ± 18.2 kg) were initially divided into two scrummaging packs. A total of 10 various scrum permutations were tested, where players were randomly swapped between the two packs. Winning scrums were determined by two observers on opposite sides of the scrum. Fatigue (100 mm visual analogue scale (VAS)) and scrummaging effort (6–20 rating of perceived exertion (RPE)) were assessed following each scrum contest. Individual scrummaging kinetics were acquired through an instrumented scrum ergometer and muscular power indicated through vertical jump heights. Student’s t-tests were used to differentiate between winning and losing scrum packs. VAS and RPE were assessed using repeated measures ANOVAs. Winning scrum packs had significantly larger combined force magnitudes (p < .002), regardless of the player contribution calculations. Additionally, winning packs had less individual movement (p = .033) and higher combined vertical jump heights (p < .001) but were not significantly heavier (p = .759) than losing scrum packs. While perceived VAS and RPE values progressively increased (p < .001), no differences in the individual scrum magnitudes were observed between the 1st and 10th scrum (p = .418). The results indicated that the combination of individual forces, variation in movement and factors related to scrummaging performance, such as vertical jump height, were associated with team scrummaging success.

The Interrater Reliability of Subjective Assessments of the Babinski Reflex

ABSTRACT The Babinski reflex is a clinical diagnostic tool; however, the interrater reliability of this tool is currently greatly contested. A comparison between rater groups with objective measurements of the Babinski reflex was therefore conducted. Fifteen recorded Babinski reflexes were assessed by 12 neurologists and 12 medical students as being either pathological or nonpathological. Kinematic and electromyographic variables were collected and used to assess which aspects of the Babinski reflex predict classification. Substantial interrater agreement within the neurologist and student groups (κ = .72 and .67, respectively) was shown; however, there were some differing aspects between what neurologists and students used to assess the reflex as determined by objective kinematic measurements.

Circadian variation of flexor withdrawal and crossed extensor reflexes in patients with restless legs syndrome

An evening state of spinal hyperexcitability has been proposed to be a possible cause of evening increases in restless legs syndrome symptoms. Thus, the objective of the current study was to assess the circadian variation in spinal excitability in patients with restless legs syndrome based on flexor withdrawal reflex and crossed extensor reflex responses. The reflexes were elicited on 12 participants with restless legs syndrome and 12 healthy control participants in the evening (PM) and the morning (AM). Reflex response magnitudes were measured electromyographically and kinematically. Both the reflexes showed a circadian rhythm in participants with restless legs syndrome but not in control participants. Changes in ankle (median flexor withdrawal reflex PM: 16.0 ° versus AM: 2.8 °, P = 0.042; crossed extensor reflex PM: 0.8 ° versus AM: 0.2 °, P = 0.001) angle were significantly larger, and ankle angular velocity (median flexor withdrawal reflex PM: 38.8 ° s−1 versus AM: 13.9 ° s−1, P = 0.049; crossed extensor reflex PM: 2.4 ° s−1 versus AM: 0.5 ° s−1, P = 0.002) was significantly faster in the evening compared with the morning in participants with restless legs syndrome, for both reflexes. For participants with restless legs syndrome, evening change in hallux angle was significantly larger than morning responses (median PM: 5.0 ° versus AM: 1.3 °, P = 0.012). No significant differences for any of the electromyographic or kinematic variables were observed between participants with restless legs syndrome and controls. The flexor withdrawal reflex and the crossed extensor reflex show a circadian rhythm in participants with restless legs syndrome suggesting an evening increase in spinal excitability. We hypothesize the circadian variation in spinal excitability may be due to a possible nocturnal form of afferent circuitry central sensitization in the dorsal horn of the spinal cord in patients with restless legs syndrome.

A lower body height and wider foot stance are positively associated with the generation of individual scrummaging forces in rugby

Abstract A scrum is a contest to win possession of the rugby ball. The current study investigated potential kinematic parameters related to individual scrummaging force production. Twenty-five “tight-five” players (body mass: 103.0 ± 12.1 kg; height: 1.85 ± .09 m) individually scrummaged against an instrumented ergometer, while body kinematics were captured. Pearson’s correlations between force generation and kinematics of individual scrummaging performances were performed. Body mass was correlated to the engagement (r = .641), peak (r = .531) and sustained (r = .438) forces. Stance width was significantly correlated with the individual scrummaging forces at engagement (r = .422) and sustained phases (r = .540) but not at peak phase (r = .369). Higher scrummaging forces were achieved at lower pelvic and back heights. The only significant relationship during the start-sustained phase was the change in pelvic height (r = −.562). Changes in right hip (r = −.477) and right knee (r = .474) angles were correlated to the change in force during engagement-peak phase. During engagement-sustained phases, change in force magnitude was correlated to changes in pelvic height (r = −.585), left hip (r = .549) and right ankle (r = .657). The change in pelvic height (r = −.518) was the only correlate during the peak-sustained phase. The presented data highlight the role of a lower body height and wider stance in the attainment of greater individual scrummaging force.