Steerable Neuroendoscopic Biopsy Forceps

Abstract

Objective: To develop a steerable neuroendoscopic instrument (SNI) based on user requirements found by several means of user research, and to evaluate this instrument on usability and safety. Only 5% of the potential intraventricular neuroendoscopy (INE) cases are currently treated with endoscopy. For the other 95%, an endoscopic approach is impossible, due to the risk of damaging the surrounding tissue by movement of the endoscopic system, needed to reach the affected areas inside the ventricles. A hand-held SNI is theorised to overcome these problems. Methods: A human-centered design (HCD) approach was taken to come to engineering solutions. Expert interviews, surveys and secondary research were performed to acquire the design input. Intermediary prototypes were developed and tested. For the final experiment, 10 participants, of which one neurosurgeon, performed a task in a box trainer. The endoscope was equipped with markers, used to evaluate the movement of the endoscope during the test by means of video analysis, comparing a rigid instrument and the new prototype in a two-tailed paired T-test. Usability was measured through a questionnaire. The spans between digit 1-2, 2-5 and 1-5 of the dominant hand of the participants was measured. Results: A biopsy forceps with a shaft length of 290mm, with a laser-cut articulating portion of 14mm and maximum bending of 40° was developed. Handle dimensions were based on a grip between the distal phalanges and the thenar area of the palm of 10th percentile hand measurements to enforce a stable grip. Significantly less non-angular movement than in the old instrument(p=0.009) was observed. Angular movement reduction was significant in one direction (p=0.032) but not in both (p=0.063). The handle prototype is slightly too large. The forces on the controls were comfortable. No relationship was detected between the finger span measurements and the usability score per participant. Conclusion: The prototype consists of a handle design based on human factor guidelines and multiple user evaluations, and an articulate tip based on DEAM’s technology, now with dimensions optimised for INE biopsy and ETV. Safety is improved by significantly limiting movement in the system during use.