Cadaver head holder for transoral surgical simulation

Estimating tongue deformation during laryngoscopy using a hybrid FEM-multibody model and intraoperative tracking - a cadaver study

Throat tumour margin control remains difficult due to the tight, enclosed space of the oral and throat regions and the tissue deformation resulting from placement of retractors and scopes during surgery. Intraoperative imaging can help with better localization but is hindered by non-image-compatible surgical instruments, cost, and unavailability. We propose a novel method of using instrument tracking and FEM-multibody modelling to simulate soft tissue deformation in the intraoperative setting, without requiring intraoperative imaging, to improve surgical guidance accuracy. We report our first empirical study, based on four trials of a cadaveric head specimen with full neck anatomy, yields a mean TLE of 10.8 ± 5.5 mm, demonstrating methodological feasibility.

Tensor Veli Palatinopexy as a Novel Treatment for Eustachian Tube Dysfunction: A Cadaveric Feasibility Study

OBJECTIVE

To demonstrate the feasibility of a novel procedure whereby a suture is placed transorally in the tensor veli palatini muscle to tighten it, thereby dilating the cartilaginous portion of the eustachian tube (ET).

STUDY DESIGN

The study design was a prospective cadaveric experiment to examine the feasibility of a novel treatment for ET dysfunction.

SETTING

Academic medical center in a research-oriented operating room with intraoperative computed tomography (CT) capabilities.

METHODS

Seven fresh-frozen cadaver heads were obtained, each of which was thawed for 36 hours prior to use. The preprocedural volumes of the cartilaginous ET were measured by filling the ET with an iodine-containing radiocontrast agent via the nasopharynx and then obtaining CT images. Submucosal flaps in the soft palate were raised, and sutures were placed in the tensor veli palatini bilaterally to increase tension. After completion of the procedure, contrast placement and CT imaging were repeated. Three-dimensional models of the ETs were created, and the volumes were measured and compared.

RESULTS

Of the 14 ETs evaluated, 13 showed an increase in postprocedure volume. On average, postprocedure volumes showed a 57% increase from preprocedure volumes (mean relative change, 57.1%; P = .013).

CONCLUSION

Placement of a tension-holding suture in the tensor veli palatini muscle can reliably dilate the cartilaginous portion of the ET. Such a procedure may be useful in the treatment of ET dysfunction.

Tumor phantom for training and research in transoral surgery

OBJECTIVE

With the paradigm shift towards minimally invasive surgical techniques such as transoral laser microsurgery and transoral robotic surgery for resection of head and neck malignancies, there is a need to enhance the surgical training of these techniques as well as provide a platform for testing new approaches and technologies. The steeper learning curve associated with minimally invasive surgical techniques may be mitigated with the use of tumor phantoms (TP) placed in cadaver models.

METHODS

An injectable TP was developed using an agar-gelatin base, unsalted chicken stock, deionized water, food coloring for visual mimicry, and iohexol for radiographic mimicry. Four percentage glutaraldehyde was used as a cross-linking agent for solidification of the TP. The TP was then injected in various mucosal anatomic sites in four unfixed cadaver heads. Visual, radiographic, and tactile mimicry was assessed via endoscopy, CT scan, and tumor dissection and palpation, respectively.

RESULTS

Tumor phantom injection was successfully achieved in all four cadaver heads. Visually and tactilely, the TP demonstrated similar color change, induration, and firmness of a typical squamous cell carcinoma (SCCa). However, ulceration that is often seen with SCCa could not be replicated. CT mimicry was compared with nine patients with known SCCa. Tumor radiodensity in the nine patients was between 77 and 110 HU (mean 86.3 HU) whereas TP radiodensity was 59 and 127 HU (mean 93.7 HU), with no significant difference between groups (P = .21).

CONCLUSION

This inexpensive, easy to apply, and unique tumor phantom could be used both to train transoral techniques and as a tool to further investigate new approaches and technologies for transoral surgery.

LEVEL OF EVIDENCE

NA.

A System for Characterizing Intraoperative Force Distribution During Operative Laryngoscopy

OBJECTIVE

This study aimed to create and validate an integrated data acquisition system for gauging the force distribution between a laryngoscope and soft-tissue during trans-oral surgery.

METHODS

Sixteen piezoresistive force sensors were interfaced to a laryngoscope and custom maxillary tooth guard. A protocol for calibrating the laryngoscope and maxilla sensors was developed using a motor-controlled linear stage and force measurements were validated against a digital scale. The system was initially tested during suspension laryngoscopy on three cadaver heads mounted on a cadaver head-holder. Intraoperative data was also collected from three patients undergoing head and neck tumor resection.

RESULTS

Mean calibration error of the scope sensors was less than 150 g (n = 3) and mean maxilla sensor error was less than 200 g (n = 3). Peak scope mag-forces of 8.09 ± 6.61 kg and peak maxilla forces of 7.62 ± 4.57 kg were experienced during the cadaver trials. The peak scope sensor mag-force recorded during the intraoperative cases was 24.7 ± 4.53 kg, and the peak maxilla force was 22.0 ± 4.60 kg.

CONCLUSION

The data acquisition system was successfully able to record intraoperative force distribution data. The usefulness of this technology in informing surgeons during trans-oral surgery should be further evaluated in patients with varying anatomic and procedural characteristics.

SIGNIFICANCE

Creation of a low-cost, integrated force-sensing system allows for the characterization of retraction forces at anatomic sites including the pharynx and larynx, brain, and abdomen. Real-time force detection provides surgeons with valuable intraoperative feedback and can be used to improve deformation models at various anatomic sites.