Acronyms and terms, defined.

A plain-language reference for the conditions, devices, and procedures discussed across this site. Linked from the For Patients & Families page so families can look up anything that comes up in clinic. Definitions stay short on purpose — if you want more depth, the linked pages go further.

A

Anterior temporal lobectomy (ATL)

An open epilepsy surgery that removes the front portion of the temporal lobe — including the deep structures (amygdala, hippocampus) where many focal seizures start. About 70–80% of well-selected patients become seizure-free.

Awake craniotomy

Brain surgery in which the patient is awake for part of the procedure, so the team can test brain function in real time. Used in DBS, epilepsy mapping, and certain tumor surgeries near speech or motor areas.

B

Basal ganglia

A group of deep brain structures that help control voluntary movement, learning, and habit formation. Many movement disorders (Parkinson's, dystonia) involve abnormal basal-ganglia activity.

BCI · Brain-computer interface

A system that records brain activity and uses it to control an external device (computer, robotic limb, communication aid). The lab works on implantable BCIs for people with paralysis from spinal cord injury.

Burr-hole anchor

A small ring-shaped device fixed into the skull where a DBS lead enters the brain. It holds the lead in place and lies under the scalp.

C

CGRP-blocker

A class of headache medications that target the calcitonin gene-related peptide pathway. Often tried before considering surgical options for chronic migraine.

Chiari malformation

A condition where the lower part of the brain (cerebellar tonsils) extends into the spinal canal, sometimes causing headache, balance problems, or cord compression. May need decompression surgery.

Closed-loop stimulation

A device that monitors brain or body signals and only delivers stimulation when something abnormal is detected. The opposite of "open-loop" stimulation, which runs on a fixed schedule.

CRPS · Complex regional pain syndrome

A burning, swelling, color-changing, hypersensitive pain condition in a hand, foot, or limb — often after an injury or surgery. Usually treated with a combination of physical therapy, medications, and (when refractory) DRG or spinal cord stimulation.

D

DBS · Deep brain stimulation

A surgical procedure in which a thin wire (lead) is placed in a specific deep part of the brain and connected to a small pacemaker-like generator under the skin. Used for Parkinson's disease, essential tremor, dystonia, OCD, and refractory epilepsy. See Track A — Movement disorders.

DBS-ANT

DBS targeting the anterior nucleus of the thalamus, FDA-approved 2018 for refractory focal epilepsy. Based on the SANTE trial; 75% median seizure reduction at seven years.

DRG · Dorsal root ganglion

The cluster of pain-sensing nerve cell bodies just outside the spinal cord, on each side at every level. DRG stimulation places a small lead near these clusters to treat focal neuropathic pain (especially CRPS in the foot or groin).

Dystonia

A movement disorder marked by sustained or repetitive involuntary muscle contractions, causing twisting postures or repetitive movements. Can be focal (one area) or generalized (whole body). Treated with medications, botulinum toxin, and DBS.

E

ECoG · Electrocorticography

Recording electrical brain activity directly from the surface of the cortex (under the skull but not penetrating the brain). Used in epilepsy monitoring and BCI research. Sometimes called subdural EEG.

EEG · Electroencephalography

Recording brain activity with electrodes placed on the scalp. Used for epilepsy monitoring, sleep studies, and many other neurological evaluations.

Engel class I

A standard classification meaning a patient is essentially seizure-free after epilepsy surgery. Often the goal of resective surgery.

Essential tremor (ET)

A common movement disorder causing rhythmic shaking, usually of the hands during action (writing, holding a cup). Distinct from Parkinson's tremor (which happens at rest). Treatable with medications, DBS, MRgFUS, or Gamma Knife.

F

FBSS · Failed back surgery syndrome

Persistent back and/or leg pain after spine surgery. Now sometimes called "persistent post-surgical pain." A common indication for spinal cord stimulation.

Focal seizure

A seizure that starts in a specific part of the brain (as opposed to a generalized seizure that involves the whole brain at once). Most surgical candidates have focal seizures.

FOG · Freezing of gait

A symptom of advanced Parkinson's where patients feel as if their feet are "stuck to the floor" when starting to walk or turning. The MJFF-funded CnF DBS trial targets levodopa-resistant FOG.

Fugl-Meyer (FMA-UE)

A standardized scale for upper-extremity motor function after stroke. The primary outcome measure in the VNS-REHAB trial of paired VNS for chronic stroke.

G

Gamma Knife

A form of stereotactic radiosurgery that uses focused gamma-ray beams to treat a small target in the brain without an incision. Used for trigeminal neuralgia, brain metastases, AVMs, and some movement disorders.

GPi · Globus pallidus internus

A deep brain target for DBS in Parkinson's disease (helps with dyskinesia, rigidity, tremor) and dystonia.

H

Hippocampal sclerosis

Scarring and shrinkage of the hippocampus, the most common pathology underlying mesial temporal lobe epilepsy. Often treatable with anterior temporal lobectomy or laser ablation (SLAH).

Hypothalamic hamartoma

A rare benign growth of brain tissue in the hypothalamus that can cause seizures (especially gelastic seizures — laughing fits) and hormonal problems. LITT is often used to treat them.

I

IPG · Implantable pulse generator

The small battery-powered device, typically implanted in the chest or abdomen, that delivers stimulation through a lead. The "pacemaker" component of DBS, SCS, VNS, and similar systems.

Intraoperative neurophysiology

Recording brain or nerve activity during surgery, both to inform the surgical plan and to study how the brain works in awake humans.

Intrathecal pump

A small implanted pump that delivers pain or spasticity medication directly to the spinal fluid, achieving better control at much lower doses than oral or IV routes.

Ischemic stroke

A stroke caused by a blocked blood vessel in the brain (versus a hemorrhagic stroke, which is bleeding). The form of stroke for which paired VNS is FDA-approved as adjunct rehab.

L

Lesionectomy

Open surgical removal of an identified lesion (tumor, cortical dysplasia, cavernoma) that is causing seizures. Can be curative when the seizure focus and the lesion are co-located.

LITT · Laser interstitial thermal therapy

A minimally invasive procedure in which a thin laser fiber is guided through a small opening in the skull to gently heat and ablate a small area of brain tissue. Used for mesial temporal epilepsy, hypothalamic hamartomas, and selected movement disorder cases.

M

Microvascular decompression (MVD)

An open surgery for trigeminal neuralgia that places a small cushion between the trigeminal nerve and the blood vessel pressing on it. Often the most durable treatment for classical TN.

MRgFUS · MR-guided focused ultrasound

An incisionless procedure where ultrasound waves are focused through the skull to create a small lesion at a precise target inside the brain. FDA-approved for essential tremor (2016), tremor-dominant Parkinson's (2018, expanded 2021), and bilateral PD (staged, 2025).

N

Neuromodulation

Using electrical, magnetic, or chemical stimulation to alter the activity of nerves or brain circuits. Most of the lab's clinical work — DBS, SCS, DRG, VNS, RNS — falls under this umbrella.

Neuroplasticity

The brain's ability to rewire itself in response to experience, learning, or injury. Paired VNS for stroke recovery aims to enhance neuroplasticity during rehab.

O

Occipital neuralgia

Sharp, shooting pain at the back of the head, caused by irritation of the occipital nerves. Treated with nerve blocks, medications, and (if refractory) occipital nerve stimulation.

ONS · Occipital nerve stimulation

A peripheral nerve stimulation system with leads placed under the skin at the back of the head over the occipital nerves. Used for refractory chronic migraine, cluster headache, and occipital neuralgia.

P

Painful diabetic neuropathy (PDN)

Burning or shooting nerve pain in the feet from long-standing diabetes. Spinal cord stimulation is FDA-approved for PDN that hasn't responded to medications.

Paired VNS

Vagus nerve stimulation delivered during a rehabilitation activity, so the stimulation pairs with each successful movement. FDA-approved 2021 for upper-extremity motor deficits after chronic ischemic stroke (based on the VNS-REHAB pivotal trial). See Track D — Stroke recovery.

Paddle lead

A flat electrode array placed in the spinal epidural space for spinal cord stimulation. Provides more focused, durable stimulation than a percutaneous (needle-placed) lead but requires a small open surgery.

Parkinson's disease (PD)

A neurodegenerative movement disorder caused by loss of dopamine-producing brain cells. Symptoms include tremor at rest, stiffness, slowness, and balance problems. Treated with medications, DBS, MRgFUS, and supportive care.

PNS · Peripheral nerve stimulation

Electrical stimulation of a specific peripheral nerve using leads placed near it (shoulder, knee, foot, post-amputation). Some PNS systems are temporary 60-day implants; others are permanent. Modern wireless systems (Nalu, StimRouter) use a small implanted lead with no internal battery — a skin-worn external transmitter delivers power transcutaneously, eliminating the chest IPG common to other neuromodulation devices.

Percutaneous

"Through the skin" — a procedure done through a needle or small puncture rather than an open incision. Trigeminal neuralgia is sometimes treated with percutaneous procedures (glycerol rhizotomy, balloon compression, radiofrequency rhizotomy).

R

Rhizotomy

An interruption of a nerve root, typically used to relieve pain or spasticity. The trigeminal nerve can be partially interrupted percutaneously (glycerol, RF, balloon compression) for trigeminal neuralgia.

RNS · Responsive neurostimulation

The NeuroPace system: a small device implanted in the skull that continually monitors brain activity through one or two leads at the seizure focus, delivering brief stimulation when abnormal patterns appear. FDA-approved 2014 for refractory focal epilepsy. Especially useful for bilateral or eloquent-cortex foci.

S

SAH · Selective amygdalohippocampectomy

A more focused alternative to anterior temporal lobectomy that removes only the deep mesial structures (amygdala, hippocampus) where many temporal-lobe seizures start. Better cognitive preservation than full ATL.

SCS · Spinal cord stimulation

Implanted device that delivers electrical pulses to the spinal cord to reduce chronic pain. Used for FBSS, CRPS, painful diabetic neuropathy. Multiple stimulation patterns available (tonic, burst, high-frequency 10-kHz).

SEEG · Stereo-electroencephalography

An epilepsy monitoring procedure in which several thin depth electrodes are placed in specific brain regions to find where seizures start. The diagnostic step that often guides resection or laser ablation. See the Research page.

SLAH · Stereotactic laser amygdalohippocampotomy

LITT used to ablate the amygdala and hippocampus in mesial temporal lobe epilepsy. Less invasive than open ATL with comparable seizure-free rates and better cognitive recovery.

STN · Subthalamic nucleus

A small deep-brain target for DBS in Parkinson's disease (helps with tremor, stiffness, slowness, and reduces medication needs).

T

Thalamotomy

An ablation in the thalamus (usually the VIM nucleus) to treat tremor. Can be done with MRgFUS, Gamma Knife, RF, or LITT.

Thalamus

A pair of deep brain structures that relay signals between the cortex and the rest of the brain. Several thalamic targets are used in DBS — VIM for tremor, ANT for epilepsy.

Trigeminal neuralgia (TN)

Severe, sudden, electric-shock-like facial pain caused by irritation of the trigeminal nerve. Treated with medications, microvascular decompression, percutaneous procedures, Gamma Knife, or (refractory) trigeminal nerve field stimulation.

Trigeminal nerve field stimulation

A peripheral subcutaneous neuromodulation approach for refractory trigeminal pain. Reversible — no nerve tissue is destroyed.

V

VIM · Ventral intermediate nucleus of the thalamus

The classic DBS or thalamotomy target for essential tremor and tremor-dominant Parkinson's.

VNS · Vagus nerve stimulation

Electrical stimulation of the left vagus nerve in the neck via a small implanted device in the chest. FDA-approved for refractory focal epilepsy (open-loop) and, separately, as paired VNS for chronic stroke recovery.

VTA · Volume of tissue activated

The estimated 3D region of brain tissue around a DBS lead contact that is influenced by stimulation. Modeling the VTA helps with programming.