Comparison of dominant- and non-dominant-hand cateract surgery outcomes by a single surgeon

PURPOSE

To compare dominant and non-dominant hand phacoemulsification surgery outcomes.

METHODS

This retrospective, single-center study included 300 patients who underwent phacoemulsification surgery by a single, right-handed surgeon. The patients were divided into two groups according to whether the surgeon used his dominant or non-dominant hand during surgery. Right eye operations were performed with the right hand, and left eye operations were performed with the left hand. Detailed ophthalmological examinations were performed on all patients preoperatively and postoperatively. Intraoperative phacoemulsification parameters, the presence of intraoperative and postoperative complications, postoperative refractive errors, visual acuity, and surgically induced astigmatism values were compared between the groups.

RESULTS

There were 171 patients in the dominant hand phacoemulsification group and 129 patients in the non-dominant hand phacoemulsification group. The distributions of age, gender, systemic diseases, and lens opacification were similar between the groups (p>0.05, for all). No statistically significant difference was observed between the two groups in terms of total operation time, phaco power, ellips fx, or ultrasonic time (p>0.05, for all). There was also no significant difference in relation to intraoperative and postoperative complication distributions, postoperative third-month refractive errors, visual acuity, or surgically induced astigmatism values (p>0.05, for all).

CONCLUSION

This study demonstrated that cataract surgery performed by a single surgeon can be effectively and safely performed using both hands on patients in a real operating theater environment. More objective results can be obtained with surgeries performed by a larger number of experienced surgeons.

Whole-hand and regional bone mineral density involvement in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by symmetric polyarthritis that can lead to joint deformity, disability, and osteoporosis. We aimed to evaluate whole hand and regional BMD in RA patients compared to controls. In addition, we evaluated the BMD of dominant versus non-dominant hands in healthy subjects. We included adult female and male RA patients and control subjects matched by age, sex, and BMI. BMD (g/cm2) was measured by DXA in lumbar spine (LS), whole hand, and three regions of interest: carpus, metacarpal bones, and phalanges. Results: 44 control subjects (49.5±11.8 y) and 60 with RA (52.7±12.7 y) were included. Significant lower BMD in RA patients was found in LS (-8.7%), dominant whole hand (-9.5%), carpus, metacarpal bones, and phalanges, and non-dominant whole hand (-8.7%), metacarpal bones, and phalanges compared to controls. A significant positive correlation was found between LS and whole-hand BMD (dominant r=.63, non-dominant r=.67). Finally, the whole hand, metacarpal bones, and carpus BMD measurements were significantly higher in the dominant hand compared to the non-dominant hand without differences in the phalangeal ROI. In conclusion, hand BMD was significantly lower in RA patients compared to control subjects and there was a significant correlation with LS BMD. We demonstrated that BMD measurements of the whole-hand, and different ROI (carpus, metacarpal bones, and phalanges) by DXA would be an easily reproducible technique to evaluate bone loss. In addition, the whole hand, metacarpal bones and carpus BMD measurements were significantly higher in the dominant hand compared to the non-dominant hand without differences in the phalanges.

A randomized controlled trial of changes in resting-state functional connectivity associated with short-term motor learning of chopstick use with the non-dominant hand

INTRODUCTION

This study identified the offline brain networks associated with motor learning of non-dominant hand chopstick use within-session.

METHODS

40 healthy right-handed adults were randomly assigned to the practice and control groups (20 each). The performance, resting-state functional connectivity (RSFC), and their correlation were compared within and between groups. Both groups repeated 9 cycles of 30 s task and rest. During the task, the practice group performed the chopstick-use practice with their left hand, while the control group held chopsticks without acquiring any skills. During the rest, both groups fixated their gaze on a fixation point. The number of times candies were moved using chopsticks with the left hand in 30 s was used to evaluate the performance. RSFC was obtained by resting-state fMRI scanning and extracting Z-scores between the right primary motor cortex and all other brain regions.

RESULTS

Both the groups improved in the post-task performance; the practice group improved more. The RSFC of the two networks increased in the practice group. One network was the RSFC between the right M1 and the right cerebellar Crus I, positively correlated with performance in the post-task. Another was the RSFC between the right M1 and the left cerebellar Crus II, positively correlated with skills in the amount of change pre- and post-task.

CONCLUSION

Offline enhancement of RSFC in these networks was shown to contribute to early chopstick-use motor learning with the left hand. These results serve as a basis for future studies on compensatory networks in individuals with stroke.

Using immersive virtual reality to remotely examine performance differences between dominant and non-dominant hands

Circle drawing may be a useful task to study upper-limb function in patient populations. However, previous studies rely on expensive and bulky robotics to measure performance. For clinics or hospitals with limited budgets and space, this may be unfeasible. Virtual reality (VR) provides a portable and low-cost tool with integrated motion capture. It offers potentially a more feasible medium by which to assess upper-limb motor function. Prior to use with patient populations, it is important to validate and test the capabilities of VR with healthy users. This study examined whether a VR-based circle drawing task, completed remotely using participant's own devices, could capture differences between movement kinematics of the dominant and non-dominant hands in healthy individuals. Participants (n = 47) traced the outline of a circle presented on their VR head-mounted displays with each hand, while the positions of the hand-held controllers were continuously recorded. Although there were no differences observed in the size or roundness of circles drawn with each hand, consistent with prior literature our results did show that the circles drawn with the dominant hand were completed faster than those with the non-dominant hand. This provides preliminary evidence that a VR-based circle drawing task may be a feasible method for detecting subtle differences in function in clinical populations.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10055-023-00794-z.

Transcranial direct current stimulation to the left dorsolateral prefrontal cortex enhances early dexterity skills with the left non-dominant hand: a randomized controlled trial

BACKGROUND

The left dorsolateral prefrontal cortex (DLPFC) is involved in early-phase manual dexterity skill acquisition when cognitive control processes, such as integration and complexity demands, are required. However, the effectiveness of left DLPFC transcranial direct current stimulation (tDCS) on early-phase motor learning and whether its effectiveness depends on the cognitive demand of the target task are unclear. This study aimed to investigate whether tDCS over the left DLPFC improves non-dominant hand dexterity performance and determine if its efficacy depends on the cognitive demand of the target task.

METHODS

In this randomized, double-blind, sham-controlled trial, 70 healthy, right-handed, young adult participants were recruited. They were randomly allocated to the active tDCS (2 mA for 20 min) or sham groups and repeatedly performed the Purdue Pegboard Test (PPT) left-handed peg task and left-handed assembly task three times: pre-tDCS, during tDCS, and post tDCS.

RESULTS

The final sample comprised 66 healthy young adults (mean age, 22.73 ± 1.57 years). There were significant interactions between group and time in both PPT tasks, indicating significantly higher performance of those in the active tDCS group than those in the sham group post tDCS (p < 0.001). Moreover, a greater benefit was observed in the left-handed assembly task performance than in the peg task performance (p < 0.001). No significant correlation between baseline performance and benefits from tDCS was observed in either task.

CONCLUSIONS

These results demonstrated that prefrontal tDCS significantly improved early-phase manual dexterity skill acquisition, and its benefits were greater for the task with high cognitive demands. These findings contribute to a deeper understanding of the underlying neurophysiological mechanisms of the left DLPFC in the modulation of early-phase dexterity skill acquisition.

TRIAL REGISTRATION

This study was registered in the University Hospital Medical Information Network Clinical Trial Registry in Japan (UMIN000046868), Registered February 8, 2022 https://center6.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000053467.

Dominant versus non-dominant hand during simulated infant CPR using the two-finger technique: a randomised study

Aims

The aim of this randomised study was to compare the two-finger technique (TFT) performance using dominant hand (DH) and non-dominant hand (NH) during simulated infant CPR (iCPR).

Methods

24 participants performed 3-min iCPR using TFT with DH or NH followed by 3-min iCPR with their other hand. Perceived fatigue was rated using visual analogue scale. Primary outcomes - (i) difference between DH and NH for compression depth (CCD), compression rate (CCR), residual leaning (RL) and duty cycle (DC); (ii) difference between first and last 30 s of iCPR performance with DH and NH. Secondary outcomes - (i) perception of fatigue between DH and NH; (ii) relationship between perception of fatigue and iCPR performance.

Results

No significant difference between DH and NH for any iCPR metric. CCR (DH: P = 0.02; NH: P = 0.004) and DC (DH: P = 0.04; NH: P < 0.001) were significantly different for the last 30 s for DH and NH. Perception of fatigue for NH (76.8 ± 13.4 mm) was significantly higher (t = -3.7, P < 0.001) compared to DH (62.8 ± 12.5 mm). No significant correlation between iCPR metrics and perception of fatigue for DH. However, a significant correlation was found for CCR (r = 0.43; P = 0.04) and RL (r = -0.48; P = 0.02) for NH.

Conclusion

No difference in performance of iCPR with DH versus NH was determined. However, perception of fatigue is higher in NH and was related to CCR and RL, with no effect on quality of performance. Based on our results, individuals performing iCPR can offer similar quality of infant chest compressions regardless of the hand used or the perception of fatigue, under the conditions explored in this study.

Video game-based therapy for the non-dominant hand improves manual skills and grip strength

The study was designed to investigate the effect of virtual reality-supported training on manual skills and grip strength in the non-dominant hand in healthy participants. Thirty participants were randomized into two groups: ErgoActive group (n=15) and control group (n=15). The ErgoActive study group received 8 weeks of training with leap motion controller-based virtual reality games. The training was done 1 day per week for 30min. The participants' hand function was evaluated using the Jebsen Taylor Hand Function Test (JTHFT), while grip strength was evaluated with a Jamar Hand Dynamometer and Pinchmeter. After 8 weeks, the ErgoActive and control groups had significantly different JTHFT, Jamar and Pinchmeter results (P<0.05). When leap motion controller-based virtual reality applications are used, healthy subjects have increased manual skills and grip strength in their non-dominant hand. These virtual reality games are an effective and fun way of improving patients' hand functions.

Style: J of occupational medicine and toxicology vibration induced injuries in hands in long-term vibration exposed workers

Introduction

Long-term vibration exposure may cause neurophysiological disturbances such as numbness and tingling, reduced grip strength and difficulties in handling small objects. The dominant hand will usually have a higher vibration exposure than the non-dominant hand, which may cause more severe neurological symptoms and signs in the dominant hand.

Methods

The study is based on 47 (36 males and 11 females) vibration exposed workers, all former patients from the department of Occupational and Environmental medicine, Gothenburg university. The comparison group consisted of 18 randomly selected subjects from the general population of Gothenburg. All participants completed several questionnaires and had a standardized medical examination. Thereafter, neurophysiological tests such as the determination of vibration and thermal perception thresholds were performed, as well as muscle strength tests in hands and fingers.

Results

The temperature perception thresholds (TPTs) and the vibration perception thresholds (VPTs) did not differ significantly between the dominant and non-dominant hand in vibration exposed workers. The referents showed a significantly better performance (p ≤ 0.02 and p ≤ 0.034, respectively) than the workers for both TPTs and VPTs, indicating a negative effect on the Aß, as well as on the Aδ and C-fibers among the exposed workers.The Purdue Pegboard test showed a significantly better performance in the dominant vs non-dominant hand in both workers (p = 0.001) and referents (p = 0.033). The referents showed a better performance than the workers in both hands (p < 0.001). The Baseline handgrip, the Pinch grip and 3-Chuck grip tests did not differ significantly between the dominant and non-dominant hand in neither workers nor referents.

Conclusions

In this study, minor differences between the dominant and non-dominant hand were noted for the Purdue Pegboard test in both workers and referents. Despite a probably higher vibration exposure in the dominant hand (mostly the right hand), however, quite similar test results were noted for VPTs, TPTs, Baseline handgrip, Pinch grip and 3-Chuck grip when comparing the dominant and non-dominant hand in the vibration exposed workers. In case of lack of time and financial obstacles, neurological tests in solely the dominant hand, will probably satisfactory reflect the conditions in the non-dominant hand.

A comparison of the characteristics and precision of needle driving for right-handed pediatric surgeons between right and left driving using a model of infant laparoscopic diaphragmatic hernia repair

PURPOSE

We compared the characteristics and precision of right and left needle driving for right-handed pediatric surgeons using a laparoscopic diaphragmatic repair model.

METHODS

Eighteen right-handed pediatric surgeons performed three needle driving maneuvers using both hands. We evaluated the required time and conducted an image analysis. The total path length, velocity, and acceleration of the needle driving were also evaluated.

RESULTS

Obtained results show the findings for the required time (s, Rt 310.78 ± 148.93 vs. Lt 308.61 ± 122.53, p = 0.93), sum of needle driving balances (mm, Rt 5.23 ± 2.44 vs. Lt 5.05 ± 3.17, p = 0.83), the gap of the needle driving interval (Rt 1.2 ± 0.93 vs. Lt 2.17 ± 1.67, p = 0.04), total path length (mm, Rt 594.03 ± 205.29 vs. Lt 1641.07 ± 670.68, p < 0.01), and average velocity (mm/s, Rt 1.92 ± 0.54 vs. Lt 5.3 ± 1.39, p < 0.01).

CONCLUSION

For right-handed pediatric surgeons, left needle driving showed almost same quality of right needle driving as regarding the precision. But left needle driving also showed too fast but not economical movement unfortunately, implying rough and risky forceps manipulation. Non-dominant hand training is necessary to avoid organ injury.

Enhanced visuo-haptic integration for the non-dominant hand

Visuo-haptic integration contributes essentially to object shape recognition. Although there has been a considerable advance in elucidating the neural underpinnings of multisensory perception, it is still unclear whether seeing an object and exploring it with the dominant hand elicits the same brain response as compared to the non-dominant hand. Using fMRI to measure brain activation in right-handed participants, we found that for both left- and right-hand stimulation the left lateral occipital complex (LOC) and anterior cerebellum (aCER) were involved in visuo-haptic integration of familiar objects. These two brain regions were then further investigated in another study, where unfamiliar, novel objects were presented to a different group of right-handers. Here the left LOC and aCER were more strongly activated by bimodal than unimodal stimuli only when the left but not the right hand was used. A direct comparison indicated that the multisensory gain of the fMRI activation was significantly higher for the left than the right hand. These findings are in line with the principle of "inverse effectiveness", implying that processing of bimodally presented stimuli is particularly enhanced when the unimodal stimuli are weak. This applies also when right-handed subjects see and simultaneously touch unfamiliar objects with their non-dominant left hand. Thus, the fMRI signal in the left LOC and aCER induced by visuo-haptic stimulation is dependent on which hand was employed for haptic exploration.

Robotic dexterity: evaluation of three-dimensional monitoring system and non-dominant hand maneuverability in robotic surgery

There has been great progress in robotic surgical technology in recent years. The aim of this study was to objectively quantify robot-enhanced dexterity. To evaluate three-dimensional monitoring and non-dominant hand maneuverability using the da Vinci Surgical System, five surgeons were asked to thread the needle through all 11 holes on the model with handling robotic instrument. Three types of suturing were carried out. In task 1, sutures were placed using the dominant hand under 3D imaging; in task 2, suturing was performed using the dominant hand under 2D imaging; and in task 3, suturing was done with the non-dominant hand under 3D imaging. Each surgeon placed three sutures in completing each task. The time to successful completion, accuracy, and the opinion of the level of difficulty were recorded. All 45 tasks were completed. The time required to place each suture (mean ± SD) was as follows: 211.7 ± 50.5 s for task 1, 331.1 ± 121.2 s for task 2, and 237.1 ± 95.7 s for task 3. Task 1 took less time than task 2 (P = 0.02). There were no differences in the times between task 1 and task 3 (P = 0.19). Robotic suturing under 3D imaging is significantly faster than under 2D imaging, and robotic suturing using the non-dominant hand does not need significantly more time than with the non-dominant hand. Technology for robotic surgery could increase the manipulative abilities.