02.20.14
A new study published in the Oxford Journal Neuro-Oncology has found further evidence that pre-operative brain mapping by nTMS (navigated transcranial magnetic stimulation) for centrotemporal area brain lesions—lesions found in the center of the brain—is beneficial to the outcome of surgery.
In the study, 100 patients with lesions located in motor eloquent areas were preoperatively mapped by a navigated brain stimulation (NBS) system which uses nTMS. These 100 patients were matched with a control group of 100 patients who had been operated on before the availability of NBS mapping at the Munich hospital.
The device used was the Nexstim NBS system, a non-invasive system for showing the location of TMS stimuli inside the brain pre-surgery by using magnetic resonance imaging (MRI) scans and proprietary electric field modeling.
The group of patients preoperatively mapped by NBS showed a significantly lower rate of residual tumor, as determined by postoperative MRI. On long-term follow-up, 12 percent of the patients in the NBS group had improved motor function after surgery, compared to only 1 percent of the patients in the control group. Additionally, using NBS mapping enabled neurosurgeons to use smaller craniotomies.
Drawbacks to nTMS the researchers pointed out include the observation that “the precision of motor mapping by nTMS can be impaired by various confounding factors, such as the definition of resting motor threshold, registration errors, navigation errors, and brain shift after durotomy.
“Nevertheless,” researchers continued, “brain shift does not impair the practical use of nTMS: data is mainly used to get an initial impression of the anatomic correlations between function and tumor prior to surgery or at least prior to craniotomy … Navigated TMS, with comparably easy and cheap availability, represents a remarkable option for non-invasive mapping because it is also based on motor evoked potentials via neuronal activation—and therefore has a close relationship to direct cortical stimulation, which is widely used by neurosurgeons. Navigated TMS can be performed in an awake patient and allows surgical planning already at the state of indication.”
Nexstim Oy is based in Helsinki, Finland. The company makes brain stimulation devices for use in neurosurgical diagnostics and therapy.
In the study, 100 patients with lesions located in motor eloquent areas were preoperatively mapped by a navigated brain stimulation (NBS) system which uses nTMS. These 100 patients were matched with a control group of 100 patients who had been operated on before the availability of NBS mapping at the Munich hospital.
The device used was the Nexstim NBS system, a non-invasive system for showing the location of TMS stimuli inside the brain pre-surgery by using magnetic resonance imaging (MRI) scans and proprietary electric field modeling.
The group of patients preoperatively mapped by NBS showed a significantly lower rate of residual tumor, as determined by postoperative MRI. On long-term follow-up, 12 percent of the patients in the NBS group had improved motor function after surgery, compared to only 1 percent of the patients in the control group. Additionally, using NBS mapping enabled neurosurgeons to use smaller craniotomies.
Drawbacks to nTMS the researchers pointed out include the observation that “the precision of motor mapping by nTMS can be impaired by various confounding factors, such as the definition of resting motor threshold, registration errors, navigation errors, and brain shift after durotomy.
“Nevertheless,” researchers continued, “brain shift does not impair the practical use of nTMS: data is mainly used to get an initial impression of the anatomic correlations between function and tumor prior to surgery or at least prior to craniotomy … Navigated TMS, with comparably easy and cheap availability, represents a remarkable option for non-invasive mapping because it is also based on motor evoked potentials via neuronal activation—and therefore has a close relationship to direct cortical stimulation, which is widely used by neurosurgeons. Navigated TMS can be performed in an awake patient and allows surgical planning already at the state of indication.”
Nexstim Oy is based in Helsinki, Finland. The company makes brain stimulation devices for use in neurosurgical diagnostics and therapy.