Forces During Skull Base Surgery
Condition: Skull Base; Pituitary; Robotics; Endonasal Surgery; Sinus Surgery
MeSH terms: Pituitary Diseases
Study type: Observational

Summary: 
      This study is designed to measure forces applied using standard surgical instruments at the
      skull base during resection of skull base lesions. This data will be useful for optimizing an
      active canula robot for assisting in skull base surgery. We hypothesize that through
      measurement of forces generated during routine endoscopic skull base surgery we will be able
      to optimize the canulas of an active canula robot for skull base surgery.
    

Detailed description: 
      At some time in their lives, 1 in 5 people will have a pituitary tumor, and 1 in 600 of these
      will have the tumor grow large enough (>1 cm in diameter) that surgical resection is
      required. Traditionally, surgery to remove pituitary tumors or other tumors at the skull base
      requires transcranial or transfacial access. In these approaches, large traumatic, often
      disfiguring, openings must be created in the patient's forehead or cheek. Endonasal skull
      base surgery reduces invasiveness resulting in less trauma, fewer complications, and shorter
      surgical time. However, despite the compelling advantages for the patient, only a small
      percentage of skull base surgeries are done endonasally. While exact statistics are not
      available, the current best estimate in the literature is that less than 50% and most likely
      less than 20% of these tumors are addressed by endonasal surgery.

      The endonasal approach is underemployed despite its demonstrated benefits to the patient
      because existing surgical instruments have limited dexterity and approach angles, and
      simultaneously manipulating several of them through a nostril while performing complex
      surgical procedures is so technically challenging that only a small number of expert surgeons
      can accomplish it. Even for these experts, mortality rates are non-negligible (0.9%), and
      there remain contraindications to the endonasal approach, including occlusion of the surgical
      site by delicate and critical neurovascular structures (e.g. carotid arteries, optic nerves),
      inability to fully reconstruct the dura due to lack of surgical tool dexterity, and long
      surgical duration. All of these contraindications are directly related to limitations in
      instrument dexterity and visualization, which motivates the development of a robotic system
      for endonasal skull base surgery. Such a robot can potentially increase surgical dexterity
      and reduce the technical complexity of the procedure for surgeons, thereby increasing the
      percentage of patient who benefit from the endonasal technique.

      While many robotic systems have been developed for intravascular interventions as well as
      natural orifice surgery though other orifices, comparatively few systems have been targeted
      at endonasal surgery. This is likely due to the smaller size of the nasal cavity and nostril
      compared to other natural orifices.

      For endonasal robots, the limited space available in the nostril opening, combined with the
      need to work dexterously within the cavities in the head, implies that instrument shafts must
      be small in diameter while enabling dexterous motions of instrument tips. A recently invented
      robot design that matches these characteristics is the concentric tube robot concept, which
      is also known as by the name active cannula.

      A robot suitable for endonasal surgery is being developed (see reference #3), however in
      order to optimize this robotic system, intraoperative data must be obtained to determine how
      the robot interacts with the patient's tissues. The aim of this study is to modify a
      traditional tool used in the operating room to allow determination of forces at the skull
      base on both hard and soft tissues. This surgical curette will be used in the standard
      fashion during endonasal skull base surgery, however will provide valuable information.

      The modified curette will consist of two segments joined by a Nano17 6-axis force sensor.
      (Image 1) The force sensor is integrated into the shaft of the instrument (a standard
      neurosurgical ring curette) and insulated from the shaft with two polyetherimide (also known
      as ULTEM) disks so that no current can be transmitted from the force sensor to the curette.
      The sensor is held to the shaft by medical grade adhesive and set screws.

      The patients will be recruited from the PIs clinical practice. Informed consent will be
      obtained. At the appropriate time during surgery this curette will be used to collect force
      date. This force transducer operates at 5V (4.8-9V range). These transducers are commonly
      used in medical and dental research (see reference #5).

      No additional operating room or anesthesia time will be required.
    

Intervention name(s): Use of force sensing surgical curette; Removal of pituitary tumor using modified curette
Intervention type(s): Device; Procedure
Intervention description(s): Use of a standard surgical curette outfitted with an in-line 6-axis force and torque transducer for collection of force data during surgery.
Observational model: Case-Only
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        All adult patients undergoing standard endonasal skull base surgery.
      
Keywords: Skull base; Pituitary; Robotics; Endonasal surgery; Sinus surgery