Paul W. Flint

Design and Integration of a Telerobotic System for Minimally Invasive Surgery of the Throat

In this paper we present the clinical motivation, design specifications, kinematics, statics, and actuation compensation for a newly constructed telerobotic system for Minimally Invasive Surgery (MIS) of the throat. A hybrid dual-arm telesurgical slave, with 20 joint-space Degrees-of-Freedom (DoFs), is used in this telerobotic system to provide the necessary dexterity in deep surgical fields such as the throat. The telerobotic slave uses novel continuum robots that use multiple super-elastic backbones for actuation and structural integrity. We present the kinematics of the telesurgical slave and methods for actuation compensation to cancel the effects of backlash, friction, and flexibility of the actuation lines. A method for actuation compensation is presented in order to overcome uncertainties of modeling, friction, and backlash. This method uses a tiered hierarchy of two novel approaches of actuation compensation for remotely actuated snake-like robots. The tiered approach for actuation compensation uses compensation in both joint space and configuration space of the continuum robots. These hybrid actuation compensation schemes use intrinsic model information and external data through a recursive linear estimation algorithm and involve compensation using configuration space and joint space variables. Experimental results validate the ability of our integrated telemanipulation system through experiments of suturing and knot tying in confined spaces.

A dexterous system for laryngeal surgery

This work presents a design overview of a novel high DoF (degrees-of-freedom) system being developed for minimally invasive surgery of the throat. The system is designed to allow remote operation of 2-3 tools with high tip dexterity to enable suturing and soft-tissue manipulation while using the patients mouth as the only entry port. The slave is a 34 DoF unit equipped with three snake-like distal dexterity units for surgical tool manipulation. Each of these units is a multi-backbone snakelike mechanism equipped with a detachable milli parallel manipulator allowing interchangeable tools to be used. The paper presents the outline of the kinematic analysis of the snake-like units and proposes one possible actuation redundancy resolution to allow further downsize scalability while reducing the risk of buckling of the primary backbone of the snake-like units. Finally, The work presents a first early experiment with a prototype of the snake-like unit.

Hydroxylapatite laryngeal implants for medialization: Preliminary report

Laryngeal implantation for medialization has improved our ability to manage the patient with vocal fold motion impairment. We present preliminary data evaluating the use of preformed hydroxylapatite laryngeal implants and instrumentation for rapid determination of implant size and position. A window in the thyroid ala is created by means of a standard fenestra template. One of 5 prosthesis templates is inserted through the window for determination of correct size and position. The corresponding implant is then inserted and secured with a hydroxylapatite shim. Thirty-five patients have been implanted for vocal fold paralysis, and 4 patients were implanted for soft tissue deficits or bowing. Thirty-one of 35 patients have reported subjective improvement (89%). Improvement was demonstrated in 13 of 15 (87%) patients with complete preoperative and postoperative objective voice function measurements. Complications include 1 implant extrusion and 1 case of airway obstruction secondary to edema. Preliminary results indicate that prefabricated hydroxylapatite implants are effective for medialization thyroplasty. Advantages include a readily available implant selection, rapid determination of correct size and position, and improved implant stabilization with a hydroxylapatite shim.

Laryngeal Synkinesis following Reinnervation in the Rat: Neuroanatomic and Physiologic Study Using Retrograde Fluorescent Tracers and Electromyography

The functional organization of laryngeal motoneurons in the nucleus ambiguus (NA) was evaluated in adult male rats before and after recurrent laryngeal nerve section and reinnervation. Using retrograde double labeling techniques with fluorescent probes, we obtained the number and position of labeled neurons by using the Bioquant 3-D imaging system. Reinnervation was documented by electromyography. In nine control animals vector analysis revealed significant (p < .05) separation of the posterior cricoarytenoid (PCA) muscle motoneurons and the thyroarytenoid and lateral cricoarytenoid (TA/LCA) muscle motoneurons. The PCA motoneurons were positioned ventromedially in the NA, and TA/LCA motoneurons were found dorsolaterally in the NA. Rostral-caudal separation was not significant. Electromyography revealed phasic electrical activity synchronous with respiration in the PCA, and activity synchronous with deglutition in the TA/LCA. In four animals surviving 15 weeks following recurrent laryngeal nerve section and primary neurorrhaphy, functional organization within the NA was lost and phasic motor unit activity synchronous with respiration was seen in the TA/LCA muscle as well as the PCA. Vector analysis revealed the reinnervating motoneurons for both the PCA and TA/LCA to be positioned dorsolaterally, similar to the control group TA/LCA motoneurons. These findings demonstrate a shift in the topographic organization of laryngeal motoneurons within the NA following reinnervation, with random organization occurring at the neurorrhaphy site.

High Dexterity Snake-Like Robotic Slaves for Minimally Invasive Telesurgery of the Upper Airway

This paper reports our efforts to develop an integrated system for telesurgery of the throat and upper airway. The system is described while focusing on the novel design of its slave robot. The slave robot is a 3-armed robot that implements novel Distal Dexterity Units (DDU’s). These DDU’s are dexterous robots for surgical tool manipulation and suturing in confined spaces. Each DDU is composed from a Snake-Like Unit (SLU) and a detachable Parallel Manipulation unit (PMU). The proposed design of the DDU’s provides an enhanced downsize scalability and distal dexterity that are crucial for medical applications such as laryngeal surgery where simultaneous manipulation of 2-3 long tools through a narrow laryngeoscope is required. The paper presents the design of these units and the experimentation results with a 4.2 mm diameter SLU to be used for constructing the first DDU for the 3-armed slave robot.

Need for emergency surgical airway reduced by a comprehensive difficult airway program.

BACKGROUND: Inability to intubate and ventilate patients with respiratory failure is associated with significant morbidity and mortality. A patient is considered to have a difficult airway if an anesthesiologist or other health care provider experienced in airway management is unable to ventilate the patients lungs using bag-mask ventilation and/or is unable to intubate the trachea using direct laryngoscopy. METHODS: We performed a retrospective review of a departmental database to determine whether a comprehensive program to manage difficult airways was associated with a reduced need to secure the airway surgically via cricothyrotomy or tracheostomy. The annual number of unplanned, emergency surgical airway procedures for inability to intubate and ventilate reported for the 4 yr before the program (January 1992 through December 1995) was compared with the annual number reported for the 11 yr after the program was initiated (January 1996 through December 2006). RESULTS: The number of emergency surgical airways decreased from 6.5 ± 0.5 per year for 4 yr before program initiation to 2.2 ± 0.89 per year for the 11-yr period after program initiation (P < 0.0001). During the 4-yr period from January 1992 through December 1995, 26 surgical airways were reported, whereas only 24 surgical airways were performed in the subsequent 11-yr period (January 1996 through December 2006). CONCLUSIONS: A comprehensive difficult airway program was associated with a reduction in the number of emergency surgical airway procedures performed for the inability of an anesthesiologist to intubate and ventilate, a reduction that was sustained over an 11-yr period. This decrease occurred despite an increase in the number of patients reported to have a difficult airway and an overall increase in the total number of patients receiving anesthesia per year.

PATHOPHYSIOLOGY AND INDICATIONS FOR MEDIALIZATION THYROPLASTY IN PATIENTS WITH DYSPHAGIA AND ASPIRATION

Medialization thyroplasty is generally considered a phonosurgical procedure for voice augmentation in patients with glottic insufficiency. This article addresses specifically the issue of dysphagia and aspiration in patients with laryngeal paralysis. A retrospective review of patients undergoing medialization thyroplasty is performed. From 1991 to 1995, 84 patients at The Johns Hopkins Medical Institutions underwent medialization thyroplasty for unilateral vocal fold motion impairment. At presentation 48 patients had isolated recurrent laryngeal nerve injury, 26 with combined superior laryngeal nerve/recurrent laryngeal nerve injury and 10 with idiopathic nerve injury. Sixty-one percent of patients had swallowing difficulties. The severity of symptoms is greater in the superior laryngeal nerve/recurrent laryngeal nerve group. Before surgery 13 patients were dependent on feeding tubes. Nine patients improved to the point at which all alimentation was taken by mouth and tube feedings were discontinued after medialization thyroplasty. One patient was subsequently converted to a full oral diet after cricopharyngeal myotomy. Three patients remained dependent on feeding tubes. The pathophysiology of dysphagia including clinical and experimental observations is reviewed. In addition, the nonsurgical and surgical approaches to treatment of patients with laryngeal paralysis are reviewed.

Applications of robotics for laryngeal surgery.

The authors present the clinical application of robotics to laryngeal surgery in terms of enhancement of surgical precision and performance of other minimally invasive procedures not feasible with current instrumentation. Presented in this article are comparisons of human arm with robotic arm in terms of degrees of freedom and discussion of surgeries and outcomes with use of the robotic arm. Robotic equipment for laryngeal surgery has the potential to overcome many of the limitations of endolaryngeal procedures by improving optics, increasing instrument degrees of freedom, and modulating tremor. Outside of laryngology, a multi-armed robotic system would have utility in microvascular surgery, procedures at the base of the skull, sinus surgery, and single-port gastrointestinal and thoracic access surgery.

Evaluation and management of bilateral vocal cord immobility.

Bilateral vocal cord immobility can be life threatening for some patients. Others, who have an open glottic chink, may have a breathy dysphonia, intermittent dyspnea, and stridor. These signs and symptoms may also be found in a number of other conditions that cause weakness or paradoxical motion of the vocal cords that mimics paralysis. These other conditions include central nervous system diseases, neuromuscular disorders, laryngospasm, and psychogenic disorders. In addition, patients with cricoarytenoid joint immobility or interarytenoid scar can also have similar symptoms at presentation. It is critical to consider the differential diagnosis of an assumed bilateral vocal cord paralysis and understand the management of paradoxical movement, weakness, joint fixation, interarytenoid scar, laryngospasm, and psychogenic disorders. The treatment for bilateral immobility should proceed only after a thorough evaluation, which might include electromyography and/or examination during general anesthesia under dense anesthetic paralysis. Reconstructive procedures are the treatments of choice, and destructive procedures should be chosen only as a last resort.

Supracricoid Laryngectomy Outcomes: The Johns Hopkins Experience

Objective: To report the oncologic and functional results from our experience in performing supracricoid laryngectomy (SCL) for selected patients with laryngeal cancer.