AVM (Arteriovenous Malformation)

An abnormal connection between arteries and veins. Where the blood vessels in the brain bypass normal brain tissue and directly diverts blood from the arteries to the veins.

Awake Craniotomy

A complex operation where the patient is awake during the procedure. This allows the neurosurgeon to test regions of the brain before they are incised or removed. The technique provides the opportunity to continuously test the patient’s functions throughout the operation. The operation is typically used to remove tumors nestled close to functional areas of the brain.


Any surgical incision into the skull, exposing the brain for neurosurgery.


An electrical field. In Navigated Brain Stimulation or Navigated Brain Therapy, the e-field is created by triggering a transcranial magnetic stimulation (TMS) coil.


A conductor used to establish electrical contact with nonmetallic part of a circuit. In Navigated Brain Stimulation and Navigated Brain Therapy, this is a small disc like piece of plastic with a gel center that is placed on the muscle that is being tracked. The electrode works with the EMG to record muscle responses to the TMS.


In Navigated Brain Stimulation and Navigated Brain Therapy, this refers to various regions of the brain. Specifically, it is a part of the brain that allows an individual to interact with and process the world via senses, motion, language and memory. It is the functioning, responsive part of the brain.

EMG (Electromyography)

A device that records electrical currents from an active muscle to produce an electromyogram.

Electromyogram – A graphic record of the electrical currents associated with muscle action.

Hemorrhagic Stroke

A stroke that occurs when a weakened blood vessel ruptures.

Ischemic Stroke

A stroke that occurs as a result of an obstruction within a blood vessel supplying blood to the brain.

Low-Grade Glioma

Low-Grade Gliomas (LGG) account for approximately 50% of all brain tumors. Gliomas originate from glial cells, most often astrocytes. Sometimes the terms “astrocytoma” and “glioma” are used interchangeably. Low-grade gliomas are classified as grade 1 or grade 2 by a tumor classification system.

MEP (Motor Evoked Potential)

An electrical response recorded from the nervous system and detected by an EMG. Evoked potentials are measured in microvolts, and time locked to determine accuracy in the response. In Navigated Brain Stimulation and Navigated Brain Therapy, the MEP is recorded from transcranial stimulation of the motor cortex.

Motor Cortex

The region of the cerebral cortex concerned with transmitting impulses to the voluntary muscles – influencing movements of the face, neck, trunk, arms and legs.

Motor Threshold (MT)

In Navigated Brain Stimulation and Navigated Brain Therapy, this is the amount of electrical energy needed for TMS to induce motor movement. The motor threshold varies widely between individuals. Once the patient’s individual motor threshold has been determined, it will provided the appropriate level of intensity of TMS dosed to a patient during the mapping procedure.

MRI (Magnetic Resonance Imaging)

A noninvasive diagnostic procedure that uses a powerful magnetic field, radio frequency pulses and a computer to produce detailed sectional images of the internal structure of the body.

fMRI (Functional Magnetic Resonance Imaging) – An MRI that can measure brain activity by detecting the changes in blood oxygenation and flow that occur in response to neural activity. When a brain area is more active it consumes more oxygen.

An fMRI is used to produce activation maps showing which parts of the brain are involved in a particular mental process. This is done by having the patient respond to different kinds of stimulation such as sound, visual or a gentle touch.

Navigated Brain Stimulation

A noninvasive procedure providing an accurate and detailed map of the critical functions of the cortex. Through the use of a standard MRI brain scan, transcranial magnetic stimulation, and EMG, this procedure excites and records responses of precise areas of the cortex for use in diagnostic applications.

Nexstim NBS System and NexSpeech® are cleared by the FDA for use in pre-surgical planning for patients undergoing brain surgery

Navigated Brain Therapy

The Navigated Brain Therapy is a noninvasive system that uses navigation to accurately target therapy directly to the cortical structures believed to be involved in brain dysfunctions. The device is CE-marked for use in patients recovering from stroke as a supplement to conventional rehabilitation.

The Navigated Brain Therapy System is not approved by the Food and Drug Administration in commercial distribution or use in the United States and is available to select physician for investigational use only.

Stereotactic Camera

A 3-D optical tracking unit, that acts like a camera to create precise navigation through the motion sensor trackers found on the glasses, coil, and digitizing pen for the Navigated Brain Stimulation and Navigated Brain Therapy Systems.

Stereotactic Radiosurgery (SRS)

A noninvasive treatment, not requiring a craniotomy, where numerous precisely focused radiation beams are used to treat tumors and other problems in the brain. It is a method that delivers high doses of radiation to the target area.

TMS (Transcranial Magnetic Stimulation)

A noninvasive technique that consists of a magnetic field emanating from a wire coil held outside of the head. The magnetic field induces an electrical current in nearby regions of the brain.

rTMS (Repetitive Transcranial Magnetic Stimulation) – Sending repetitive and focused stimulation to one region of the brain. rTMS is not used for motor mapping, it is used for FDA cleared speech and language mapping (NexSpeech®) and in clinical trials for therapies such as stroke.