Neurosurgery Glossary | Mark Hornyak, MD

A

Acromegaly

A hormonal disorder caused by excess growth hormone, usually from the pituitary gland, that can enlarge bones and soft tissues.

Arthroplasty

a surgical procedure commonly known as joint replacement surgery. It involves removing a damaged, diseased, or worn-out joint and replacing it with an artificial implant (prosthesis) made of metal, plastic, or ceramic. The goal is to relieve pain, correct deformities, and restore mobility. In the spine is also called disc replacement or artificial disc surgery.

Adenoma

A usually benign tumor that develops from glandular tissue, including pituitary tissue.

Allograft

Bone or tissue graft material donated from another person, often used in reconstructive or fusion procedures.

Ambulatory

Able to walk, or describing care performed without an overnight hospital admission.

Aneurysm

A weakened area of a blood vessel wall that bulges outward and may be at risk for rupture.

Angiography

Imaging of blood vessels using contrast dye, performed with catheter angiography, CT angiography, or MR angiography.

Annulus

The tough outer ring of an intervertebral disc.

Anticoagulant

A medication that reduces blood clotting, sometimes described as a blood thinner.

Aphasia

Difficulty understanding or producing language, often related to injury, stroke, tumor, or other brain disorder.

Arachnoid membrane

The middle layer of the meninges, the protective coverings around the brain and spinal cord.

ACDF

Anterior cervical discectomy and fusion (ACDF) is a surgery that removes a damaged disc in the neck and stabilizes the spine with a bone graft or implant.

Arteriovenous malformation (AVM)

An abnormal connection between arteries and veins that can occur in the brain or spinal cord.

Arthrodesis

Surgical fusion of a joint or spinal segment to limit motion.

Astrocytoma

A tumor arising from astrocytes, support cells found in the brain and spinal cord.

Ataxia

Loss of coordination that may affect walking, balance, or limb movement.

Autograft

Bone or tissue taken from one area of a patient and used elsewhere in the same patient.

ALIF

Anterior lumbar interbody fusion (ALIF) is a spine surgery through the abdomen that removes a damaged disc and fuses the vertebrae together for stability.

Anterior cervical discectomy and fusion

A surgery in the front of the neck that removes a herniated or degenerated disc and fuses the adjacent vertebrae for long-term stability.

Apraxia

Apraxia is a condition where the brain has trouble planning or coordinating everyday movements even though the muscles are strong.

Arachnoid cyst

An arachnoid cyst is a fluid-filled sac between layers of the protective tissue around the brain or spinal cord, and it may cause headaches or neurological symptoms if large.

Artificial disc replacement

Artificial disc replacement is a procedure that removes a damaged spinal disc and replaces it with a synthetic implant to preserve motion.

Axial pain

Axial pain refers to discomfort that stays centered in the neck, mid-back, or low back rather than shooting into the arms or legs.

B

Benign intracranial hypertension

Elevated pressure around the brain without a clear mass lesion; also called pseudotumor cerebri.

Biopsy

Removal of a small tissue sample so it can be examined under a microscope.

Bone graft

Bone material used to help bones heal together, commonly during spinal fusion.

Brachial plexus

A network of nerves traveling from the neck into the shoulder, arm, and hand.

Brainstem

The lower part of the brain that connects to the spinal cord and helps control vital functions.

Basilar invagination

Basilar invagination is a structural condition where the top of the spine pushes upward into the base of the skull, which can compress the brainstem.

Bone spur

A bone spur is a small bony projection that can form along the edge of a joint or vertebra and may pinch nerves or irritate nearby tissue.

Brain tumor

A brain tumor is an abnormal growth of cells inside the skull that can cause headaches, seizures, or changes in thinking depending on its size and location.

Burr hole

A burr hole is a small hole drilled through the skull to relieve pressure, drain fluid, or access the brain during surgery.

C

Carotid artery

One of the major arteries in the neck that supplies blood to the brain.

Cauda equina

The bundle of nerve roots below the end of the spinal cord in the lower spinal canal.

Cauda equina syndrome

A serious condition from compression of the lower spinal nerve roots, often involving leg symptoms and bowel or bladder dysfunction.

Cavernous malformation

A cluster of abnormal small blood vessels that may occur in the brain or spinal cord.

Central nervous system (CNS)

The brain and spinal cord.

Cerebellum

The part of the brain important for coordination, balance, and movement control.

Cerebrospinal fluid (CSF)

Clear fluid that circulates around the brain and spinal cord.

Cerebrum

The largest part of the brain, responsible for functions such as movement, sensation, language, and thought.

Cervical spine

The neck region of the spine, made up of seven vertebrae.

Chiari malformation

Downward displacement of part of the cerebellum through the opening at the base of the skull.

Coma

A state of unconsciousness in which a person cannot be awakened.

Concussion

A usually temporary disturbance of brain function after a blow or rapid movement of the head.

Corpectomy

Removal of the body portion of a vertebra, often to decompress the spinal cord or reconstruct the spine.

Cranial nerve

One of twelve paired nerves that arise directly from the brain and serve the head, neck, and special senses.

Craniectomy

Removal of a portion of skull bone without immediate replacement.

Cranioplasty

Surgical repair or reconstruction of a skull defect.

Craniotomy

Surgical opening of the skull, usually with replacement of the bone flap at the end of the operation.

CT scan

An imaging test that uses x-rays and computer processing to create cross-sectional images.

Cage

A cage is an implant used in spinal fusion surgery to hold bone graft material and maintain disc height while the vertebrae fuse together.

Carpal tunnel syndrome

Carpal tunnel syndrome is a nerve compression condition in the wrist that causes numbness, tingling, and weakness in the hand.

Cervical disc herniation

A cervical disc herniation occurs when inner disc material pushes out in the neck and presses on a nerve, often causing arm pain or numbness.

Cervical myelopathy

Cervical myelopathy is spinal cord compression in the neck that can cause weakness, balance problems, and changes in hand coordination.

Cervical radiculopathy

Cervical radiculopathy happens when a nerve root in the neck is pinched, producing pain, numbness, or weakness radiating into the shoulder or arm.

Clonus

Clonus is a series of involuntary, rhythmic muscle contractions usually caused by nerve irritation in the spinal cord or brain.

Compression fracture

A compression fracture is a collapse of a vertebral body in the spine, often due to trauma or weakened bone, and can cause sudden back pain.

Corticosteroid

A corticosteroid is a medication used to reduce inflammation and swelling around nerves or the spinal cord in conditions like disc herniation.

CSF leak

A CSF leak happens when cerebrospinal fluid escapes from its normal compartment around the brain or spinal cord, often causing headache and neck stiffness.

D

Diplopia

Double vision.

Disc

A cushion between spinal vertebrae, made of a tough outer ring and softer center.

Disc degeneration

Age-related or wear-related changes in a spinal disc that may contribute to pain or nerve compression.

Dura mater

The tough outer membrane covering the brain and spinal cord.

Dysphagia

Difficulty swallowing.

Decompression

Decompression is surgery that removes bone or tissue pressing on the spinal cord or nerves to relieve pain, weakness, or numbness.

Deep brain stimulation

Deep brain stimulation is a procedure that implants electrodes in the brain to deliver mild electrical pulses and improve movement or pain symptoms.

Degenerative disc disease

Degenerative disc disease describes wear-and-tear changes in spinal discs that can lead to pain, stiffness, or nerve irritation.

Dermatomes

Dermatomes are skin areas served by specific spinal nerves, and doctors use them to identify which nerve is affected by pain or numbness.

Discectomy

A discectomy is surgery to remove part or all of a damaged spinal disc that is pressing on a nerve root.

Disc extrusion

Disc extrusion is when the soft center of a spinal disc breaks through the outer layer and extends into the spinal canal or nerve root area.

Disc protrusion

Disc protrusion refers to a bulging spinal disc that extends outward but has not fully ruptured through the outer disc layer.

Disc replacement

Disc replacement is a surgical option that swaps a damaged spine disc for an artificial one to preserve more normal motion.

Dorsal column

The dorsal column is a spinal cord pathway that carries fine touch and position sense from the body to the brain.

Drop foot

Drop foot is weakness in the muscles that lift the front of the foot, often caused by nerve compression in the spine or leg.

E

Edema

Swelling caused by excess fluid in tissues.

Electroencephalography (EEG)

A test that records electrical activity of the brain, often used in seizure evaluation.

Electromyography (EMG)

A test that measures muscle and nerve electrical activity.

Endoscope

A thin camera instrument used to see inside body spaces through small openings.

Endovascular

Inside a blood vessel, often referring to catheter-based treatment.

Ependymoma

A tumor arising from cells lining the ventricles of the brain or central canal of the spinal cord.

Epidural

The space outside the dura mater, either in the skull or spinal canal.

Epidural hematoma

A blood clot located between the skull or spine and the dura.

Epidural steroid injection

An injection of steroid medication into the epidural space to reduce inflammation around irritated nerve roots.

Epilepsy

A disorder involving recurrent seizures caused by abnormal electrical activity in the brain.

F

Facetectomy

Surgical removal of part or all of a facet joint.

Fluorescence-guided surgery

Use of special light and imaging agents to help visualize selected tissues during surgery.

Fluoroscope

A device that provides real-time x-ray images during procedures.

Foramen

An opening through which nerves or blood vessels pass.

Foraminotomy

Surgical enlargement of a foramen to relieve pressure on a nerve.

Fusion

A procedure intended to join two or more bones together so they heal as one unit.

Foraminal stenosis

Foraminal stenosis is narrowing of the nerve exit paths in the spine, which can pinch nerves and cause arm or leg pain.

G

Gadolinium

A contrast agent sometimes used during MRI to improve visualization of certain tissues.

Gamma Knife

A brand name for focused stereotactic radiosurgery equipment.

Glasgow coma scale (GCS)

A scoring system used to describe level of consciousness after brain injury or illness.

Glia

Support cells of the nervous system.

Glioblastoma (GBM)

An aggressive malignant brain tumor arising from glial cells.

Glioma

A tumor that develops from glial cells in the brain or spinal cord.

Gliosis

Gliosis is scarring in the brain or spinal cord tissue that develops after injury or inflammation.

H

Hematoma

A collection of clotted blood.

Hemiplegia

Paralysis affecting one side of the body.

Hemorrhage

Bleeding from a blood vessel.

Herniated nucleus pulposus (HNP)

A disc herniation in which inner disc material protrudes through the outer ring and may compress nerves.

Hydrocephalus

Abnormal buildup of cerebrospinal fluid within the brain ventricles.

Hypophysis

Another name for the pituitary gland.

Hypothalamus

A region at the base of the brain involved in hormone regulation and basic body functions.

Headache

A headache is pain felt in the head or neck and may be caused by muscle tension, spinal problems, or pressure in the brain.

Hemangioblastoma

A hemangioblastoma is a rare, usually benign tumor made of blood vessel cells, most often found in the brain or spinal cord.

I

Ictal

Related to the time during a seizure.

Image-guided surgery

Surgery using navigation and imaging technology to help localize anatomy and guide instruments.

Immunotherapy

Cancer treatment that uses or modifies the immune system to fight disease.

Instrumentation

Implants such as screws, rods, plates, or cages used to stabilize the spine.

Intracerebral hematoma

A blood clot within the brain tissue.

Intracranial pressure (ICP)

Pressure inside the skull.

Intrathecal

Within the space containing cerebrospinal fluid.

Ischemia

Insufficient blood flow to tissue.

Intradural tumor

An intradural tumor grows inside the protective covering of the spinal cord or brain and may compress nerves or the spinal cord itself.

Intramedullary tumor

An intramedullary tumor forms within the spinal cord substance and often requires specialized surgical treatment.

K

Kyphoplasty

An image-guided procedure using a balloon and bone cement to stabilize selected compression fractures.

Kyphosis

A forward spinal curvature, normal in the thoracic spine but abnormal when excessive or in other regions.

Kyphotic deformity

Kyphotic deformity is an abnormal forward rounding of the spine that can cause pain, posture changes, and spinal cord or nerve compression.

L

Lamina

The back portion of a vertebra forming part of the spinal canal roof.

Laminectomy

Removal of one or more laminae to decompress nerves or access the spinal canal.

Laminotomy

Removal of part of a lamina, often to access a herniated disc or relieve nerve pressure.

Leptomeninges

The two delicate inner coverings of the brain and spinal cord: pia and arachnoid.

Lordosis

An inward spinal curve, normally present in the neck and lower back.

Lumbar puncture

A procedure to sample cerebrospinal fluid from the lower back, also called a spinal tap.

Lumbar spine

The lower back region of the spine.

Lumbar disc herniation

A lumbar disc herniation occurs when disc material in the lower back pushes against a nerve root, often causing leg pain or sciatica.

Lumbar radiculopathy

Lumbar radiculopathy is nerve irritation in the lower spine that causes shooting pain, numbness, or weakness down the leg.

M

Magnetic resonance angiography (MRA)

MRI-based imaging of arteries, often used in the head and neck.

Magnetic resonance imaging (MRI)

An imaging test using magnets and radio waves to create detailed images without x-rays.

Meninges

The protective membranes covering the brain and spinal cord.

Meningioma

A tumor arising from the meninges; many are benign but may still require monitoring or treatment.

Metastasis

Spread of cancer from one body site to another.

Microdiscectomy

A focused operation to remove herniated disc material compressing a nerve.

Minimally invasive

A technique using smaller openings and specialized instruments to limit tissue disruption in selected procedures.

Myelogram

Imaging of the spinal canal after contrast is placed into the cerebrospinal fluid space.

Myelopathy

Dysfunction of the spinal cord.

Medulloblastoma

Medulloblastoma is a type of brain tumor most commonly seen in children that starts in the cerebellum and may cause headache and coordination problems.

Metastatic spine tumor

A metastatic spine tumor is cancer that has spread to the spine from another part of the body and can cause pain, weakness, or spinal instability.

Microvascular decompression

Microvascular decompression is surgery to relieve nerve irritation by moving a blood vessel away from a nerve in the brain.

Motor cortex

The motor cortex is the brain area that controls voluntary movement, and injury there can affect strength and coordination.

N

Nerve root

A spinal nerve as it leaves or travels near the spinal canal.

Neuralgia

Pain occurring along the course of a nerve.

Neurofibroma

A tumor involving peripheral nerve tissue.

Neurology

The medical specialty focused on diagnosis and non-surgical treatment of nervous system disorders.

Neuropathy

Disease or dysfunction of peripheral nerves.

Neurosurgery

The surgical specialty treating selected disorders of the brain, spine, nerves, and cerebrovascular system.

Normal pressure hydrocephalus

A condition involving enlarged ventricles and symptoms that may include gait difficulty, cognitive change, and urinary issues.

Nucleus pulposus

The soft inner center of a spinal disc.

Neurogenic claudication

Neurogenic claudication is leg pain and weakness caused by spinal canal narrowing, often felt after walking or standing.

Neurolysis

Neurolysis is a procedure that frees a nerve from scar tissue or compression to relieve pain and improve function.

Neuromonitoring

Neuromonitoring uses electrical tests during surgery to track nerve and spinal cord function and help keep the nervous system safe.

O

Occiput

The back part of the head.

Oncology

The field of medicine focused on cancer diagnosis and treatment.

Orthotic

A brace or external support for a limb or the spine.

Osteophyte

A bony overgrowth, commonly called a bone spur, often associated with arthritis or degeneration.

Outpatient

Care or a procedure performed without hospital admission.

Ommaya reservoir

An Ommaya reservoir is a small implant placed under the scalp to allow direct delivery of medication into the fluid around the brain.

P

Papilledema

Swelling of the optic nerve head, sometimes associated with increased intracranial pressure.

Paraplegia

Paralysis of the lower part of the body.

Paresthesia

An abnormal sensation such as numbness, tingling, or pins and needles.

Pedicle

A bony bridge connecting the vertebral body to the back elements of the spine.

Peripheral nervous system

Nerves outside the brain and spinal cord.

Pituitary gland

A hormone-producing gland at the base of the brain.

Posterior fossa

The back compartment of the skull containing the cerebellum and brainstem.

Pseudomeningocele

A collection of cerebrospinal fluid outside the normal spinal canal or skull covering, often from a dural leak.

Pain management

Pain management includes treatments and medications aimed at reducing discomfort from spine, nerve, or brain conditions.

Pars defect

A pars defect is a stress fracture in part of a vertebra that can cause back pain and may lead to spine instability.

Peripheral nerve

A peripheral nerve carries signals between the spinal cord or brain and the limbs, and injury can cause weakness, numbness, or pain.

PLIF

Posterior lumbar interbody fusion (PLIF) is a spine surgery from the back that removes a damaged disc and fuses the vertebrae with an implant.

Posterior cervical fusion

Posterior cervical fusion is a surgery from the back of the neck that joins vertebrae together to stabilize the spine.

Pseudoarthrosis

Pseudoarthrosis is a failed spinal fusion where the bones do not fully join, often causing pain or instability after surgery.

Q

Quadriplegia

Paralysis affecting all four limbs.

R

Radiculitis

Inflammation or irritation of a spinal nerve root.

Radiculopathy

Symptoms caused by irritation or compression of a spinal nerve root, often including pain, numbness, tingling, or weakness.

Radiologist

A physician trained to interpret medical imaging and perform selected image-guided procedures.

Radiotherapy

Treatment using radiation, commonly for tumors and selected other conditions.

Revascularization

Restoration of blood supply to an area.

Recurrent disc herniation

Recurrent disc herniation occurs when a spinal disc re-herniates after an earlier surgery, causing a return of pain or nerve symptoms.

S

Saccular aneurysm

A rounded pouch-like aneurysm, sometimes called a berry aneurysm.

Sagittal plane

An anatomical plane dividing the body into left and right portions.

Schwannoma

A usually benign tumor arising from Schwann cells, which form nerve insulation.

Sciatic nerve

The large nerve traveling from the pelvis down the back of the thigh and into the leg.

Seizure

Abnormal electrical activity in the brain that causes a change in movement, sensation, awareness, or behavior.

Shunt

A tube used to divert fluid from one body space to another.

Spina bifida

A congenital defect involving incomplete formation of part of the spine.

Spinal fusion

Surgery intended to make two or more vertebrae heal together into one stable segment.

Spinal instability

Loss of normal spinal support or alignment from trauma, degeneration, tumor, or other causes.

Spinous process

The bony projection at the back of a vertebra that can often be felt under the skin.

Spondylolisthesis

Forward slippage of one vertebra relative to another.

Spondylosis

Degenerative arthritic change of the spine.

Stenosis

Narrowing, commonly of the spinal canal, nerve openings, or a blood vessel.

Stereotactic radiosurgery

Highly focused radiation treatment delivered to a precisely defined target.

Stroke

A sudden brain injury caused by blocked blood flow or bleeding.

Subarachnoid hemorrhage

Bleeding into the space between the arachnoid membrane and pia mater.

Subdural hematoma

A blood clot beneath the dura mater.

Syringomyelia

A fluid-filled cavity within the spinal cord, sometimes associated with Chiari malformation.

Sacroiliac joint

The sacroiliac joint connects the spine to the pelvis and can cause lower back or buttock pain when irritated.

Scoliosis

Scoliosis is a sideways curve of the spine that can affect posture and sometimes cause back pain.

Spinal cord compression

Spinal cord compression is pressure on the spinal cord that can cause pain, weakness, numbness, and difficulty walking.

Spinal cord stimulator

A spinal cord stimulator is an implanted device that sends mild electrical pulses to the spinal cord to help reduce chronic pain.

Spinal decompression

Spinal decompression is surgery that removes bone or disc material pressing on the spinal cord or nerves to relieve symptoms.

Spinal tumor

A spinal tumor is an abnormal growth in or near the spinal cord that may cause pain, numbness, or weakness.

Spondylolysis

Spondylolysis is a stress fracture in a vertebra that can lead to back pain and may be a precursor to slippage of the spine.

Subdural hygroma

A subdural hygroma is a fluid collection between the brain and its outer covering that can build up after head injury.

T

Thalamus

A deep brain structure involved in sensory relay and other functions.

Thrombus

A blood clot attached to a vessel wall.

Transsphenoidal approach

A surgical route to the pituitary or skull base through the nose and sphenoid sinus.

Transverse process

A side projection of a vertebra where muscles and ligaments attach.

Tremor

An involuntary rhythmic movement of a body part.

Trigeminal nerve

The fifth cranial nerve, providing sensation to much of the face and motor supply to chewing muscles.

Trigeminal neuralgia

Severe episodic facial pain in the distribution of the trigeminal nerve.

Thoracic spine

The thoracic spine is the middle section of the back where the ribs attach, and it can be affected by discs, tumors, or fractures.

TLIF

Transforaminal lumbar interbody fusion (TLIF) is a spinal fusion surgery done from the back and side to remove a damaged disc and stabilize the lower spine.

Traumatic brain injury

Traumatic brain injury is brain damage caused by an external force, such as a fall or accident, and may lead to headaches, memory issues, or balance problems.

Tumor resection

Tumor resection is surgery to remove a brain or spinal tumor while preserving healthy surrounding tissue.

U

Ulnar nerve

A major arm nerve traveling near the elbow and into the hand.

Ultrasound

Imaging that uses high-frequency sound waves.

Ulnar neuropathy

Ulnar neuropathy is irritation or compression of the ulnar nerve, often causing numbness or tingling in the ring and little fingers.

V

Vascular

Related to blood vessels.

Vasospasm

Narrowing of blood vessels from spasm, sometimes occurring after aneurysm rupture.

Ventricle

A fluid-filled chamber in the brain containing cerebrospinal fluid.

Ventriculostomy

Creation of an opening into a brain ventricle, often for cerebrospinal fluid drainage.

Vertebra

One of the bones of the spinal column.

Vertebral artery

An artery running through the neck vertebrae that supplies the back of the brain.

Vertebroplasty

Injection of bone cement into a fractured vertebra to stabilize selected compression fractures.

Vertigo

A sensation that you or the environment is spinning or moving.

Visual field testing

Testing of peripheral vision, also called perimetry.

W

White matter

Nervous system tissue containing nerve fibers that carry signals between regions.

WHO tumor grading

A World Health Organization system used to classify tumors by expected behavior and aggressiveness.

X

X-ray

Ionizing radiation used to create images, especially of bones and certain internal structures.