Three Dimensional Motion Analysis of Hand Tremors During Endoscopic Ear Surgery

Abstract

Background: Endoscopic surgery is developing in various clinical specialties. During ear endoscopic surgery, a surgeon has to hold an endoscope with one hand and operate the surgical instruments with another hand. Therefore, the stability of the surgeon's hand affects the field of surgical view and quality of the surgery considerably. There are few techniques which are used during surgery to stabilize the endoscope. However, no study has evaluated the efficacy of such techniques in detail. This study examined the three dimensional movement of an endoscope to compare and evaluate the effect of various stabilization techniques to reduce the hand tremor while using the endoscope.

Methods: A non-randomized controlled trial involving 15 medical students was conducted in Tottori University, Japan. Subjects held an endoscope with their non-dominant hand and manipulated it using three different stabilization techniques i.e. with resting the elbow on the table, resting the endoscope on the ear canal, both with the elbow on the table and endoscope on the ear canal. For the control, subjects were made to use the endoscope without any stabilization technique. The endoscopic movement was measured with and without using the stabilization techniques.

Results: The results obtained in this study indicated that manipulating the endoscope with resting the elbow on the table restrains both vertical (Y-axis) and optical axis (Z-axis) direction of tremor, and manipulating the endoscope by resting it on the ear canal restrains both vertical (Y-axis) and horizontal axis (X-axis) direction while the combined use of both the techniques reduces the endoscope movement in all the three X, Y and Z axes.

Conclusion: In conclusion, concomitant use of both techniques appears to be clinically beneficial in endoscopic ear surgery.

Keywords: endoscopy; otologic surgical procedure; tremor.

Fig. 1.

The pictorial representation of endoscopic setup. The three directions of endoscopic movement with respect to visual axis (X, Y and Z- axes) are shown in solid red lines (A). The object is behind the board (B). EAC, external auditory canal.

Fig. 2.

The pictorial representation of each stabilization techniques setup. EAC stabilization setup are shown in (A). Elbow stabilization setup are shown in (B).

Fig. 3.

Distribution of subjects in high and low dexterity groups. Study subjects (n = 15) were divided into two groups by displacement less than (high dexterity group, black dots, n = 8) or above (low dexterity group, red dots, n = 7) the 50th percentile of the endoscope movement (= 7.5 mm, presented as quarter circle in black filled line).

Fig. 4.

Position displacement of the endoscope in X-axis (A), in Y-axis (B) as a function of control and three stabilizing techniques. Vertical dashed lines indicate, from left to right, the control data without any stabilization, elbow stabilization, EAC stabilization, and both elbow plus EAC stabilization. In panels A and B, high dexterity group (High group, filled black line, n = 8, √(X² + Y²) < 7.5) displays unchanged slope from control to all three stabilizations, when compared with low dexterity group (Low group, filled red line, n = 7, √(X² + Y²) ≥ 7.5) after stabilization of EAC and Elbow + EAC (A). Details are described in the text. Definitions: Closed circles = mean endoscope displacement; Vertical bars = standard deviation of mean values of displacement at control, Elbow, EAC and Elbow + EAC. *P < 0.05; **P < 0.005; and ***P < 0.0005. #P < 0.05; ##P < 0.005; and ###P < 0.0005. * represents intra-group difference and # represents intergroup difference. EAC, external auditory canal.

Fig. 5.

Position displacement of the endoscope in Z-axis as a function of control and three stabilizing techniques. High dexterity group (High group, filled black line, n = 8) displays unchanged slope from control to all three stabilizations, when compared with low dexterity group (Low group, filled red line, n = 7) after stabilization of EAC and Elbow + EAC. Details are described in the text. Definitions: See Fig. 4. *P < 0.05; **P < 0.005; and ***P < 0.0005. #P < 0.05; ##P < 0.005; and ###P < 0.0005. * represents intra-group difference and # represents intergroup difference. EAC, external auditory canal.