Minimally invasive surgical techniques are less invasive than open surgery techniques used for the same purpose and are therefore desirable due to their offering reduced trauma, reduced pain & scarring, more rapid recovery, and reduced post-surgical complications. Some of these techniques can be performed robotically. In neurosurgery, attempts have been made at a needle-based minimally invasive robotic approach to treating some conditions. These systems are generally stereotactic robotic systems that use straight needle trajectories with image guidance to hit specific targets at a specific worksite within the brain, in a manner similar to that of a standard brain biopsy. This needle-based approach results in less damage to the surrounding brain tissue during delivery, at the expense of offering no appreciable dexterity once the target is reached. One particular condition that would benefit to a needle based approach that offers dexterity at the worksite is an intracerebral hemorrhage.
Approximately 1 in 50 people will have an intracerebral hemorrhage (ICH) at some point in their lives, and the one-month mortality rate is approximately 40%. ICH occurs when a blood vessel in the brain ruptures and a collection of blood, referred to herein as a “clot” or “hematoma,” accumulates within the cranial cavity and compresses the brain. The clot can be treated with drugs or surgical evacuation via open craniotomy to help remove the clot and decompress the brain. While one would expect decompression via clot removal to result in improved patient outcomes, there is no clinical data supporting this for the majority of ICH patients. Benefits of various treatments have only been shown in select patients with small, superficial lesions and a good preoperative performance status. There remains no treatment of proven clinical benefit for typical ICH patients. In standard open surgical procedures, the brain substance is cut with electrocautery and tubular retraction systems, with or without endoscopic assistance, and Archimedes screw-type devices are applied to remove the clot. These current ICH treatments, however, provide only minimal improvement in outcomes.
Some of the ineffectiveness of the current ICH treatments can be attributed to permanent brain injury that is caused by the hemorrhage and is irreversible even with clot removal. Neurosurgeons, however, generally believe that there is a volume of at-risk brain tissue that can be salvaged and returned to pre-injury function if its condition is optimized through decompression. The ability to restore brain tissue to pre-injury function does not necessarily depend on complete removal of the clot. For example, by some estimates, clinically meaningful decompression can begin when approximately 25-50% of the clot is removed.
Decompression through removal of the clot resulting from the ICH, referred to herein as “evacuation” or “debulking,” is known to help optimize the condition of the brain. Decompression, however, can be challenging for certain clot locations and shapes, particularly those resulting from deep hemorrhages. For many clots, an operative trajectory of any significant dimension would result in a volume of tissue disruption that is greater than that which would be saved by its evacuation. As a result, only superficial clots are candidates for evacuation using current operative approaches.