Patrick J. Codd

Concentric Tube Robot Design and Optimization Based on Task and Anatomical Constraints

Concentric tube robots are catheter-sized continuum robots that are well suited for minimally invasive surgery inside confined body cavities. These robots are constructed from sets of precurved superelastic tubes and are capable of assuming complex 3-D curves. The family of 3-D curves that the robot can assume depends on the number, curvatures, lengths, and stiffnesses of the tubes in its tube set. The robot design problem involves solving for a tube set that will produce the family of curves necessary to perform a surgical procedure. At a minimum, these curves must enable the robot to smoothly extend into the body and to manipulate tools over the desired surgical workspace while respecting anatomical constraints. This paper introduces an optimization framework that utilizes procedure- or patient-specific image-based anatomical models along with surgical workspace requirements to generate robot tube set designs. The algorithm searches for designs that minimize robot length and curvature and for which all paths required for the procedure consist of stable robot configurations. Two mechanics-based kinematic models are used. Initial designs are sought using a model assuming torsional rigidity. These designs are then refined using a torsionally compliant model. The approach is illustrated with clinically relevant examples from neurosurgery and intracardiac surgery.

Robotic neuro-emdoscope with concentric tube augmentation

Surgical robots are gaining favor in part due to their capacity to reach remote locations within the body. Continuum robots are especially well suited for accessing deep spaces such as cerebral ventricles within the brain. Due to the entry point constraints and complicated structure, current techniques do not allow surgeons to access the full volume of the ventricles. The ability to access the ventricles with a dexterous robot would have significant clinical implications. This paper presents a concentric tube manipulator mated to a robotically controlled flexible endoscope. The device adds three degrees of freedom to the standard neuroendoscope and roboticizes the entire package allowing the operator to conveniently manipulate the device. To demonstrate the improved functionality, we use an in-silica virtual model as well as an ex-vivo anatomic model of a patient with a treatable form of hydrocephalus. In these experiments we demonstrate that the augmented and roboticized endoscope can efficiently reach critical regions that a manual scope cannot.

A recurrent cerebral arteriovenous malformation in an adult

Arteriovenous malformations are generally considered to be cured following angiographically proven complete resection. However, rare instances of AVM recurrence despite negative findings on postoperative angiography have been reported in both children and adults. In this paper, the authors present the case of a 33-year-old woman with 2 AVM recurrences. This patient represents the oldest case of recurrent AVM, and the first adult double recurrence reported in the literature. The case is presented, the radiological and surgical features are considered, and the literature on recurrent AVMs is reviewed.

Percutaneous Steerable Robotic Tool Delivery Platform and Metal MEMS Device for Tissue Manipulation and Approximation: Closure of Patent Foramen Ovale in an Animal Model

Background—Beating-heart image-guided intracardiac interventions have been evolving rapidly. To extend the domain of catheter-based and transcardiac interventions into reconstructive surgery, a new robotic tool delivery platform and a tissue approximation device have been developed. Initial results using these tools to perform patent foramen ovale closure are described. Methods and Results—A robotic tool delivery platform comprising superelastic metal tubes provides the capability of delivering and manipulating tools and devices inside the beating heart. A new device technology is also presented that uses a metal-based microelectromechanical systems–manufacturing process to produce fully assembled and fully functional millimeter-scale tools. As a demonstration of both technologies, patent foramen ovale creation and closure was performed in a swine model. In the first group of animals (n=10), a preliminary study was performed. The procedural technique was validated with a transcardiac hand-held delivery platform and epicardial echocardiography, video-assisted cardioscopy, and fluoroscopy. In the second group (n=9), the procedure was performed percutaneously using the robotic tool delivery platform under epicardial echocardiography and fluoroscopy imaging. All patent foramen ovales were completely closed in the first group. In the second group, the patent foramen ovale was not successfully created in 1 animal, and the defects were completely closed in 6 of the 8 remaining animals. Conclusions—In contrast to existing robotic catheter technologies, the robotic tool delivery platform uses a combination of stiffness and active steerability along its length to provide the positioning accuracy and force-application capability necessary for tissue manipulation. In combination with a microelectromechanical systems tool technology, it can enable reconstructive procedures inside the beating heart.

Primary pediatric intraspinal sarcomas. Report of 3 cases.

Sarcomas that arise from within the spinal canal are rare, particularly within the pediatric population. In general, these primary intraspinal sarcomas are highly aggressive, posing unique treatment challenges with respect to surgery and choice of adjuvant therapy. The goal must be to obtain the most complete resection possible to minimize the risk of recurrence and metastasis, while preventing potential neurological deficits that may result from aggressive surgery. Among these primary intraspinal sarcomas are malignant peripheral nerve sheath tumors and members of the Ewing sarcoma family of tumors. The authors present 3 cases of unique spinal sarcomas in children-2 malignant peripheral nerve sheath tumors in patients without neurofibromatosis and an intradural extraosseous Ewing sarcoma arising from the sensory component of a lumbar spinal nerve-and discuss their management and outcome with a review of the current literature.

Endoscopic burr hole evacuation of an acute subdural hematoma

Acute subdural hematoma evacuations frequently necessitate large craniotomies with extended operative times and high relative blood loss, which can lead to additional morbidity for the patient. While endoscopic minimally invasive approaches to chronic subdural collections have been successfully demonstrated, this technique has not previously been applied to acute subdural hematomas. The authors report their experience with an 87-year-old patient presenting with a large acute right-sided subdural hematoma successfully evacuated via an endoscopic minimally invasive technique. The operative approach is outlined, and the literature on endoscopic subdural collection evacuation reviewed.

Novel pressure-sensing skin for detecting impending tissue damage during neuroendoscopy

OBJECT Endoscopy plays an increasingly important role in minimally invasive neurosurgery. Visual feedback from the endoscope tip helps the surgeon prevent unwanted tissue contact. However, critical feedback regarding tissue deformation and trauma from proximal endoscope components is currently unavailable. A system for force feedback along the endoscope length could provide significant clinical benefit by warning of impending damage. The authors manufactured and tested a novel pressure-sensing polymer skin for use in pressure feedback during intracranial endoscopy. METHODS A photolithography process on a silicon wafer was used to produce a pattern of 80-μm-tall extrusions to serve as a positive mold for the sensor array. A thin layer of polydimethylsiloxane polymer was molded onto these features. Demolding the polymer from the wafer and sealing with another polymer layer resulted in microchannels. These microchannels were filled with a conductive liquid metal and connected to recording hardware. Spiral channel patterns were designed to create a 3 × 3 array of pressure-sensor pads, which were wrapped around a standard neuroendoscope operating sheath. Pressure readings from the compressed sensor array were translated into a color-coded graphic user interface. Calibration experiments were conducted, and the sensor was evaluated through cortical compression tests on explanted ovine brain. RESULTS The sensing endoscope operating sheath was successfully calibrated to detect and display pressures within a range consistent with normal and tissue-threatening compressions. CONCLUSIONS Force-feedback mechanisms for the neuroendoscopist are critically lacking with contemporary endoscopes. The authors designed a pressure-sensing skin technology for improved pressure feedback during endoscopy as a means for minimizing collateral tissue damage during endoscopy.

Fourth ventricular neurocystercercosis presenting with acute hydrocephalus

Neurocysticercosis is an infection caused by the larvae of the pork tapeworm Taenia solium. Parenchymal lesions commonly present with seizure activity and intraventricular lesions can cause hydrocephalus. A 33-year-old female patient presented in a comatose state with acute hydrocephalus and a fourth ventricle lesion. She underwent placement of an external ventricular drain. Resection of the fourth ventricle lesion through a suboccipital approach allowed for restoration of normal cerebrospinal fluid (CSF) flow and relief of midbrain compression. The lesion was resected intact and the patient returned to normal neurological function. No CSF diversion procedure was necessary. The patient was discharged on cysticidal and steroid therapy. We concluded that surgical resection of lesions in the fourth ventricle attributed to neurocysticercosis is appropriate when brainstem compression is prominent. Resection may also avoid the need for permanent CSF diversion. We also reviewed the evidence-based management strategies described in the literature.

Diffuse central neurocytoma with craniospinal dissemination

Central neurocytomas (CN) are benign central nervous system (CNS) tumors of neuroglial origin that represent 0.25 to 0.5% of all intracranial tumors in adults and an even smaller proportion of pediatric CNS tumors. These tumors characteristically occur in the subependymal layer of the lateral ventricle near the foramen of Monro and appear as sharply demarcated, solitary lesions. Surgical resection is considered curative, as the reported recurrence rate is less than 5% for patients with localized disease. In this report, we describe the case of a three-year-old boy with a diffuse CN with craniospinal dissemination identified at the time of diagnosis. Given the extensive nature of the disease, surgical resection was not indicated and he underwent a chemotherapeutic regimen of vincristine and carboplatin. At 18 months followup, the patient has completed 6 of 8 total cycles of vincristine and carboplatin and serial imaging shows stable disease within the craniospinal axis.

Initial Experience with High-Definition Camera-On-a-Chip Flexible Endoscopy for Intraventricular Neurosurgery

OBJECTIVE The usefulness of existing neuroendoscopes has been limited by either decreased range of motion or suboptimal image resolution. The flexible high-definition chip-camera endoscope has emerged as a potential solution to the shortcomings of available instruments by combining superior flexibility and image quality in order to better operate within spatially constrained intraventricular operations. CASE DESCRIPTION Here we describe a 36-year-old woman who presented with hydrocephalus caused by an obstructive mass arising from the tectum. A high-definition camera-on-a-chip flexible neuroendoscope was used to sample the tectal mass after a traditional neuroendoscope was used to perform a third ventriculostomy. CONCLUSIONS As demonstrated by this initial experience, the use of high-definition camera-on-a-chip flexible endoscopy may provide enhanced intraoperative visualization and application for intraventricular neurosurgery.