Robotic Thymectomy by Kemp H. Kernstine M.D., Ph.D. (with interview)

[editor’s note: In this interview, and his accompanying article, Dr. Kernstine commented on the use of the da Vinci surgical system in these sensitive myasthenia gravis cases.]

“Myasthenia gravis is an uncommon disease, which strikes young females in their 20s to 30s. In 10 to 15% of all cases, the patient will have a thymoma, which is a cancer of the thymus. In the past, the method of treatment has been a median sternotomy, although you can imagine that a young 20-year-old female being told they need to have this extensive surgery doesn’t sit very well,” said Dr. Kemp Kernstine, MD, PhD, director of the department of thoracic surgery and lung cancer and the thoracic oncology program at the City of Hope Medical Center in California.

The open surgery method requires extensive dissection from the diaphragm, all the way up to the thyroid, into the left and the right chest; in short, the surgeon has to completely remove all the mediastinal tissue in these patients.

As an alternative to the traditional open method for myasthenia gravis cases, Kernstine makes a selective use of the da Vinci surgical system.

“We use the robot selectively. If we feel this is going to be a curative, not a palliative procedure for this patient, we will typically choose robotics,” Kernstine said.

Myasthenia gravis can be a terribly debilitating disease in these patients, he added. “They have blurry vision, droopy eyelids, difficulty talking and swallowing, as well as muscle and respiratory weakness. They can wind up on a ventilator,” Kernstine said.

While Kernstine does not intentionally use robotic surgery to remove a thymus from a myasthenia gravis patient, the doctor did note his success so far with the operation.

“Where’s the cost effectiveness of adding robotics? I think it’s going to be in a wider, more complete resection, with less likelihood for local recurrence,” he said.


City of Hope’s large medical robotics program uses three of the original da Vinci models, he said. “We haven’t got the ‘S’ model yet, although I’ve gone up to Sunnyvale to examine it, and it has some features that may be more useful to the non-prostate, non-heart surgeon. The robotic arm chassis is a little lighter. The older system has these arms that stick out away from the patient’s abdomen or chest, and with the ‘S’-model, these arms are collapsible so they don’t hit against each other when they’re moving at extremes of robot,” Kernstine added.

Robotic Thymectomy
Kemp H. Kernstine M.D., Ph.D.
City of Hope Medical Center and Beckman Research Institute
Los Angeles, California


The thymus is vestigel organ that exists in the upper anterior mediastinum draped over the great vessels and superior aspect of the heart from the thyroid gland to the mid-heart level. Its function is largely in immunological development largely prior to birth. As its functional importance is lessened, it begins to atrophy, roughly at 6 to 9 months of age. By 20 years of age, the thymus is fairly small and in the majority of patients there is minimal tissue by 40 years of age. Several disease processes can occur within thymic tissue; including cancer, hyperplasia, the presence of foreign active tissues such as the thyroid, parathyroid and germ cell tissue, remnants stem or multipotent cells that may develop into defined tissues such as eye, bone, cartilage, hair etc.. The most common reason for removal of the thymus is to evaluate and diagnose masses or nodules within the thymic gland suspicious for cancer. Historically the thymus removal or thymectomy was performed in the same fashion as heart surgery, by median sternotomy or by thoracotomy, incisions in the midportion or on either side of the chest. As a result, patients would remain hospitalized for 5 to 10 days and would not return to work for 6 weeks, not being able to lift any more than 10 pounds for that period of time.

The presence of myasthenia gravis is another common reason for thymectomy. Since the early 1900s the correlation between thymic pathology and myasthenia symptoms, weakness with repetitive use, has been recognized. Basic science discoveries have found that the thymus is an important organ in the initiation and potentially perpetuation of the disease. The resultant development of antibodies directed against the post synaptic endplate acetylcholine receptors results in gradual and persistent destruction so that the clinical presentation of weakness continues to worsen until the patient is unable to breathe or perform any of the simple routine daily tasks. In any patient, this is a devastation, but the typical patient is female in their 20s to 40s, the prime of their lives. Numerous medications have been developed to control, but not arrest, the symptoms. Approximately 10% of patients will spontaneously go into remission regardless of the management.

The potential of surgical removal arresting the disease was theorized in the early 1900s, but it was not until the 1940s that the first series of thymectomies was reported. The video-assisted and transcervical techniques were later developed and in relatively small retrospective series, appear to provide a similar remission rate as the open technique, 30 to 60% by 5 to 8 years. Though, they do not appear to have the same rate of remission as the more surgically-aggressive extended thymectomy, and complete removal of the thymus and all peri-thymic tissue from diaphragm up to the thyroid gland and into both chests through a median sternotomy and additional neck incision, over 80% at 10 years. Unfortunately, these percentages are from retrospective reviews with nonstandard definitions of remission. As a result, many neurologists and their patients are reluctant to subject themselves to a major operation of which the majority are performed by a large midline sternal incisions and are associated with a relatively long recovery. Concerns have been raised about the less invasive approaches, the transcervical thymectomy and the video-assisted technique, as they may not remove all of the thymus or the remnant thymic tissue often found in the anterior mediastinal fat, potentially reducing the likelihood for remission.

Computer-assisted surgical systems or robotic surgery was approved by the Food and Drug Administration in the mid to lower 1990s. The first United States robotic chest procedures were performed in 2002. One of the first was thymectomy. Our own thymectomy series started in the Fall of 2002. Our earliest findings have found reduced pain with smaller incisions, earlier return to preoperative function, reduced cost of care and apparent reduced likelihood for postoperative myasthenic crisis. We have yet to demonstrate that the greater dexterity, visibility and likely ability to more precisely remove all thymic tissue will result in an improved remission rate. Perhaps, with this approach, it will be a potential therapy for patients earlier in the course of their disease, potentially increasing the rate of remission.

Canadian Firm Draws Big Funding for Developing Device for Robotic MicroSurgery: $27 Million

By John J. Otrompke, JD

A robotic surgery device intended for “image-guided microsurgery” has drawn big funding and expertise, and is expected to human trials in Canada this year.

The NeuroArm, being developed by the University of Calgary in conjunction with engineering firm MacDonald, Dettwiler and Associates is capable of both biopsy-stereotaxy and microsurgery, according to Dr. Garnette Sutherland, MD, a practicing surgeon and professor of neurosurgery at the University of Calgary.

Funding for Delicate Procedures

MDA is the engineering firm which has designed a robotic arm called CanadArm for the space shuttle and international space station. Sutherland said the multi-year effort has been funded with $27 million Canadian, including $10 million for research and development.

“Probably the first patient will be a person with a brain tumor, which will probably be very accessible, and we’ll use NeuroArm for part of it,” said Sutherland.

Sutherland added that developments in science furnished a reason for building a new robotic surgery device.

“Everything that has happened in neurosurgery could be linked to advances in lesion localization, starting with an air-injection process called pneumo-encephalography in about 1914. Then in the 1930s they introduced contrast angiography. But the real inventions that revolutionized neurosurgery came in the 1970s, with CT imaging and MR imaging. Then in the late 1990s they introduced MR imaging into the operating room, further enhancing lesion localization, and allowing craniotomies to become ever smaller.

“There has been a trend towards minimalist surgery, with the smallest incision about a centimeter and the smallest instrument a few millimeters,” he continued.

The NeuroArm can manipulate spatial tissue as small as 50 microns, he said.

“When we started our project, we had engineers from MDA come to the operating room at Calgary and park there and watch how neurosurgeons manipulate tools, pass them to the nurse and back again to the head, because the robot has to integrate as a team member,” said Sutherland, adding that NeuroArm was the firm’s first foray into surgical robots.

Why a New Robot?

Sutherland stressed that while he envisions the NeuroArm, if it ever gets approved as operating in a different context from the Da Vinci, there may be areas in which the NeuroArm offers improvements, at least for certain procedures, he said.

“I don’t see us as competing with the da Vinci, which is a really good robot for minimally invasive endoscopic procedures,” said Sutherland, who has worked with a da Vinci device. “We work in a different field, biopsy-stereotaxy and microsurgery, although endoscopy is also a form of microsurgery, since there’s a microscope,” he added. The Da Vinci system is the only surgical robot presently licensed in Canada, according to Sutherland.

Microsurgical procedures include plastic surgery, opthalmologic surgery, and laryngology, “where people do ear operations, and try to replace the little bones,” he said.

Sutherland said the NeuroArm will also try to make other contributions to the field of robotic surgery, especially in the areas of haptics and sound.

“Surgeons discriminate tissue plains based on the feel, if one is softer, and one firmer, and they take advantage of the soft tissue boundary between tumor or aneurysm and the brain. The surgeon must feel what our machine feels. What is the alphabet of touch and what are the ingredients that make up touch, and can engineers recreate that for surgeons?”

The other improvement being worked on is sound, according to Sutherland. “We want to recreate the sound of surgery. When a surgeon has a little suction device, and it sucks on something soft, it makes a little different pitch from when it sucks on something hard.”

Sutherland said he hopes the NeuroArm will be licensed soon. The good thing about working with a company like MDA is that the aerospace industry is very good at documenting safety, and that’s what the regulatory bodies for medicine are all about.

British Universities Study Rehabilitation for Spinal Cord Injuries with Intelligent Exoskeleton Robot

By John J. Otrompke, JD for Medical Robotics Magazine

A team of research institutions in the United Kingdom are developing a new sort of rehabilitation robot. The prototype NeXOS system is designed to be an intelligent exoskeleton which can be instructed to remember and repeat specific limb movements which have been programmed by a physiotherapist.

“We specifically identified spinal cord injuries, and wanted to look at lower limb rehabilitation. These patients go through a process of needing a lot of passive movement, and a lot of them have incomplete lesions,” said Dr Sue Mawson, PhD, a researcher at Sheffield Hallam University in the United Kingdom.

The only robot currently available for rehabilitation in the UK is the Manus system, developed by MIT., according to Mawson.

Public funding for the NeXOS project was awarded in 2002, and the study began the following year, and was complete by 2006. Team members interviewed physiotherapists in designing the prototype.

Another feature of the robot is that physiotherapists can monitor their patient's progress from another location, such as non-clinical settings including their own homes, gyms and sports centers.
The NeXOS design is relatively low-cost and could be deployed over a large number of patients easily were it approved, according to David Bradley, PhD, professor of mechatronic systems at the University of Abertay Dundee in Scotland.

Other collaborators include the University of Sheffield and Barnsley Teaching Hospitals.