Neurologist exhibited new
new technologies in oncology
at the American Association of
Neurological Surgeons

Novel Approaches for Brain Diseases Are Discussed at AANS Meeting

May 13, 2009
by Lynn Shapiro, Writer
Trials showing the efficacy of cortical stimulation to beat treatment-resistant depression; a surgical pump for post-herpetic neuralgia; and an implantable camera that slices nerves to stop excessive sweating in teens, were just a few of the studies presented at the American Association of Neurological Surgeons 77th Annual Meeting last week.

Neurologists also exhibited new techniques in oncology. For example, one study found that in spinal tumors, using lower doses of radiosurgery with the Gamma Knife is not only effective but preserves hearing, typically impaired when spinal tumors are resected.

In the imaging arena, a researcher found that a technique called fluorescence-guided tumor resection helps neurosurgeons differentiate gliomas from surrounding brain tissue.

To see the latest neurosurgical research, go to: Meanwhile, here's a DOTmed News roundup of some novel devices:

Cortical Brain Stimulation With Electrodes Improves Treatment-Resistant Depression

An investigational technique called cortical stimulation may offer an alternative for patients who have suffered from major depression for years, but who have failed to respond to treatment with anti-depressants, according to a new study presented by Emad Eskandar, MD, from Massachusetts General Hospital and Harvard Medical School.

Dr. Eskandar said that imaging and transcranial magnetic stimulation trials have demonstrated that the left dorsolateral prefrontal cortex (DLPFC) area of the brain plays a critical role in patients with major depressive disorder. These findings prompted him to target electrodes to this region of the brain.

He recruited 12 patients for this pilot study. The patients received either sham stimulation or active treatment for eight weeks. After this period, all patients were switched over to active treatment.

During the minimally invasive procedure, the electrodes were placed epidurally, via a small craniotomy. Patients' depression was assessed using several rating scales, including the well-known Hamilton Depression Rating Scale.

At 8 weeks, Hamilton scores showed that depression improved by 22 in the active treatment group versus 3 percent in the sham group. Scores of well-being on the other rating scales also climbed.

What's more, patients continued to feel better when they were tested at six months and again one year following the initial surgery.

Dr. Eskandar reportedly told attendees at the conference that patients in his study had been ill for many years and had no other options available to them. On average, they had tried 10 medications but failed to respond to any of them.
This is what is called refractory depression.

He said his next step would be launch a larger trial while honing his technique. He noted that "the advantages of cortical stimulation are that it is reversible, nondestructive, less invasive than other forms of stimulation, and can be modified by adjustment of the stimulator settings after implantation."

Surgical Pump for Shingles

Every year, 200,000 patients in the United States develop shingles, for which there is no cure. Shingles (herpes zoster) is a viral infection that causes a painful rash. It often appears as a band of blisters that typically affects the torso.

Other parts of the body may be involved such as the neck, face, scalp or limbs. The pain from shingles can be excruciating, and the cause might not be immediately evident. The virus lies inactive in all persons who have been infected with chickenpox and decades later, the virus can reappear as shingles. While some patients have mild cases and recover fully, other patients suffer from post-herpetic neuralgia, a painful syndrome that often cannot be adequately treated with pain-relieving medications.

Post-herpetic neuralgia causes the skin to remain painful and ultra sensitive for months or even years after the rash has resolved. The current treatment for this painful syndrome is oral medication. However, 15 percent of shingles patients, including those on oral medications, continue to have severe pain a full year after having the shingles virus. Further, high doses of oral narcotics are often necessary to control the pain experienced by people with this condition. This may lead to side effects, such as sleepiness, which can negatively affect quality of life.

Researchers at University at Buffalo investigated the use of a surgical pump to deliver medication to patients with post-herpetic neuralgia. The results of this study were presented by Andrew J. Fabiano, MD.

A proven technique for delivering medications directly to the spinal sac is through the surgical implantation of a mechanical pump, Dr. Fabiano explained. He said that typically, the pump sits under the skin in the abdomen and has a small tube that goes into the spinal sac. Medications travel from the pump, through the tube, and enter the spinal fluid that surrounds the spinal cord and peripheral nerves.

This type of system is used to deliver medications in many conditions including multiple sclerosis and chronic back pain. So why not use it to combat neuralgia that is resistant to medication? Dr. Fabiano thought. He selected five patients with shingles and treated them with the drug-delivery device during a seven-year period. Patients' narcotic medications were delivered directly to their spinal sacs.

The mean follow-up time was 5.7 years, with the following outcomes:

All patients experienced more than a 50 percent improvement in pain and there were no complications related to the pump/catheter drug delivery systems.

"In conclusion, medications delivered directly to the spinal sac through a surgically implanted drug pump can help reduce pain in shingles in patients who do not respond to oral medications," Dr. Fabiano said.

Deep Brain Stimulation for Dystonia

Dystonia is a very complex, highly variable neurological movement disorder characterized by involuntary muscle contractions. As many as 250,000 people in the United States have dystonia, making it the third most common movement disorder behind essential tremor and Parkinson's disease.

Dystonia results from abnormal functioning of the basal ganglia, a deep part of the brain, which helps control coordination of movement. Patients with generalized primary dystonia suffer from repetitive twisting movements or abnormal postures due to involuntary muscle contractions.

This can be a severely disabling disease, which starts around age 10, with initial misdiagnosis fairly common. Further, it can be a socially debilitating disease, especially for young people, since peer acceptance plays an important role during one's teen years.

Researchers at Ludwig-Maximilians University in Munich investigated the safety and efficacy of deep brain stimulation (DBS) in children with severe cases of treatment-resistant primary dystonia. The results of this study were presented by Jan H. Mehrkens, MD.

Over the last decade, the globus pallidus internus (GPi) of the basal ganglia of the brain, has been identified as the most promising target for treating dystonia. However, very little is known about long-term efficacy and side effects of using this treatment at early disease onset in children suffering from primary generalized dystonia, Dr. Mehrkens said.

In the past nine years, Dr. Mehrkens has treated 48 patients using this approach. She implanted electrodes in patients under general anesthesia with MRI-guided stereotaxy and then implanted an internal pulse generator.

The entire patient group experienced significant improvement in symptoms as early as the first week, and symptoms abated further improved in the 58 month follow-up period.

The mean improvement in the movement score was highly significant: patients enjoyed a 67.4 percent greater control over their movement at 3 months, 75.4 percent more control at 12 months and 83.5 percent more control over the long term.

Minimally invasive Technique Helps Excessive Sweating in Teens

An estimated 3 percent of the world population, or about 197 million people suffer from some form of hyperhidrosis (excessive sweating), many of whom do not receive proper diagnosis or treatment.

Hyperhidrosis is a medical condition in which the body sweats three to four times the normal amount. This can lead to excessive sweating of the hands, underarms, feet, or face, and in severe cases, impede day-to-day functions most people take for granted.

While the exact cause of hyperhidrosis is unknown, researchers have linked it to over-activity of the nerves that send signals to the sweat glands in the skin.

Teenagers suffering from hyperhydrosis often experience social, emotional, and physical problems, exacerbating what is often an already vulnerable period of growth and maturity.

To combat this odd and embarrassing condition, researchers used a minimally invasive surgical technique. The results of this study were presented by Scott D. Wait, MD.

The surgical procedure described by Dr. Wait involves two tiny incisions in the chest wall just under the armpit on both sides.

A miniature camera mounted on a surgical telescope is used to access the chest and divide the sympathetic nerves responsible for the excessive sweating. This approach results in virtually undetectable scars and patients can leave the hospital the same day the surgery is performed.

Surgery was performed on 54 teens, aged 10 to 17, followed over a period of eight years. The following outcomes were achieved:

Hand, facial and underarm sweating all slowed by more than 90 percent. Sweating of the soles of the feet was hardest to treat: this type of sweating decreased in only 71 percent of patients.

When asked whether they were satisfied with the surgery results, 98 percent of patients responded "yes."

Low-dose Radiosurgery to Preserve Hearing in Skull Tumors

Brain tumors at the base of the skull may be treated effectively with low doses of Gamma Knife radiosurgery, to preserve both hearing and facial nerve function, another study found.

Vestibular schwannomas (frequently called acoustic neuromas) are common skull-base brain tumors that account for 57 percent of all nerve sheath tumors and 5 percent of all primary brain tumors.

These tumors arise near nerves that control hearing and movements of the face. Typically, patients notice unilateral (one-sided) or asymmetrical hearing loss, but sometimes these tumors are found incidentally in patients with normal hearing.

Other symptoms may include tinnitus (ringing in the ear), and dizziness/loss of balance. These tumors can impact facial nerves, causing facial numbness, weakness, or paralysis on one side of face. If the tumor grows large enough, it may press against nearby brain structures (such as the brainstem and the cerebellum), becoming life threatening or even fatal.

Researchers at the University of California, San Francisco (UCSF), analyzed outcomes in thousands of patients who underwent Gamma Knife radiosurgery treatment for vestibular schwannomas.

In this analysis of 6,438 patients, when Gamma Knife radiosurgery was used to treat vestibular schwannomas, there appeared to be a good outcome if facial nerve function and hearing was preserved prior to treatment.

There was an overall facial nerve function of 96 percent and hearing preservation of 51 percent with an average follow up of almost four years.

Patients who had the best facial and hearing outcomes were those patients treated with lower doses of radiosurgery at 13 Gray (Gy) or less. These patients had a higher rate of hearing preservation compared to patients treated with higher doses (61 percent versus 50 percent in the higher-dose group) and improved facial nerve function (98 percent versus 95 percent.)

Source: American Association of Neurological Surgeons