Apnea - to stop breathing intermittently, may be due to compression on the brainstem

Arachnoid - one of the three membranes covering the brain, appears to resemble a spider web. There are 3 layers of covering of the brain and spinal cord- the pia, arachnoid and dura

Arachnoiditis - inflammation of the arachnoid

Aspirate - inhaling fluids into the lungs. (Inability to swallow properly can allow fluid into the lungs.)

Ataxia - inability to coordinate movement. Stumbling when walking, or inability to maintain a fluid gait when asked to walk a straight line.

Atrophic - changes in the muscle that create an appearance of being wasted away.

Atrophy - wasting away of the muscle, often due to lack of use or inability to exercise a muscle.

Basilar Invagination - the base of the skull and the first cervical vertebra dent inward, causing pressure on the brainstem or upper cervical spinal cord.

Catheter - small, soft plastic tube used to drain fluid. A Foley catheter is often inserted into the bladder for surgery. A shunt catheter can be inserted into a syrinx or the ventricles of the brain.

Cerebellum - the lower part of the brain that lies in the posterior fossa and is responsible for coordination and fluidity of movement.

Cerebellar tonsils - the lower part of the cerebellum; in the Chiari I malformation, the cerebellar tonsils hang down into the upper spinal canal

Cerebrospinal fluid - clear, water-like fluid that flows around the brain and spinal cord, and acts to cushion the structures. The total CSF volume in an adult is about 150ml (or about 1 pint).

Cervical - pertaining to the neck

CINE MRI - or CINE MRI flow-study is a special test that looks at the flow of cerebrospinal fluid from the posterior fossa and into the spinal canal.

Clonus - abnormal, uncontrolled jerking of the foot when the ankle is jerked upward.

Cranial nerves - a set of 12 nerves in the brain that control motor and sensory functions.

Cranio-cervical junction - the area where the bottom of the skull connects to the top of the spine

Diplopia - symptom of seeing double, or double vision.

Dura Mater - the tough outer covering that surrounds the brain and forms the spinal canal

Dysequilibrium - inability to maintain proper balance. Often noted as stumbling or falling to one side.

Dysesthesia - an unpleasant sensation. A symptom of pins and needles or tingling when skin is touched.

Dysphagia - inability to swallow properly. Often leads to aspiration.

Ectopia - abnormal herniation, displacement or hang down of tissue

Electrocautery - a small instrument that uses heat and is used in many surgeries to stop bleeding.

Filum terminale - the band that extends from the end of the spinal cord to the tailbone

Hemisphere - one half of the upper portion of the brain.

Herniation - abnormal protrusion (or overhang) of tissue. Some MRI reports will read herniation of the tonsils- this means the tonsils are hanging down too far.

Hoffman's sign - (or reflex) an abnormal reflex that is tested by placing the fingers in a neutral position, and (painlessly) flicking the nail of the middle finger. If positive, the other fingers will abnormally flex in response.

Hydrocephalus - abnormal, over filling of the spinal fluid pockets (ventricles) in the brain. Can cause symptoms such as headache, balance problems, incontinence and memory problems.

Hydrosyringomyelia - a fluid cavity in the spinal cord. May also be referred to as syrinx, or syringomyelia.

Incidental Finding - a finding that is unexpected, or unrelated to symptoms. May refer to a person who has a finding on MRI, but has no symptoms.

Laminectomy - removal of the roof bone (or posterior arch) of a vertebra.

Limb ataxia - inability to maintain fluid movement of the arm or leg. Inability to touch finger to nose properly.

Lumbar - referring to the lower most part of the spine, the low back.

Meninges - the 3 layers of covering that surround the brain and spinal cord. Consists of the pia mater, the arachnoid, and the dura mater.

Meningitis - inflammation of the meninges. May be due to bacterial or viral infection.

Myelogram - special radiology study that involves injecting contrast dye into the spinal canal and taking x-rays of where the dye travels. The test is often followed by a CAT scan of the area. The test is often done to determine if there is blockage of flow or a nerve root that is being compressed. This test is less commonly used than MRI.

Myelomeningocele - herniation or protrusion of the spinal cord through a defect in development of the neural tube- seen in infants. Often associated with Chiari type II.

Nystagmus - abnormal bobbing of the eyes. Can be seen when looking to the side or up and down.

Paraparesis - weakness in both legs

Parasthesia - abnormal sensation in the extremity.

Pericranium - a muscle layer between the skull and scalp.

Periosteum - a muscle layer between the skull and scalp. (Called pericranium when on the skull).

Posterior Fossa - a general term for the compartment in the back part of the skull. This is where the brainstem, cerebellum and cerebellar tonsils lie.

Posterior fossa decompression - a general term for surgery to enlarge the compartment at the back of the skull

Pseudomeningocele - a collection of spinal fluid that develops outside the dura; while small collections are not of concern, larger collections can crowd and compress tissues

Scoliosis - curvature of the spine

Shunt - small, soft plastic tube that is used to drain fluid.

Sleep apnea - to stop breathing intermittently when sleeping. Symptom can be described as waking up short of breath or gasping for air.

Syncope - spells of passing out, or fainting (loss of consciousness). Different from a seizure.

Syringomyelia - the condition of having an abnormal fluid cavity in the spinal cord.

Syrinx - abnormal fluid cavity in the spinal cord.

Tethered cord - when the spinal cord becomes stuck to the surrounding structures due to scarring or a congenital problems or is pulled down by the band at the end of the cord

Thoracic - refers to the area of the chest; from the shoulder blades, through the ribs, to about the belt-line

Tinnitus - ringing in the ears.

Tonsillar ectopia - a small amount of hang down of the tonsil tissue of the cerebellum.

Tonsillar herniation - more descent or hang down of the cerebellar tonsils into the upper spinal canal. The classic description is 3 - 5 mm or more of hang down below the opening at the base of the skull (the foramen magnum).

Tonsils - a small, often rounded mass of tissue. There are several tonsils in the body, including in the throat, in the intestine, or in the brain. In reference to Chiari, indicates the tissue at the bottom of the cerebellum that can protrude downward, causing a plug effect.

Traction - to pull something; in neurosurgery usually refers to pulling on the skull with tongs or a halter

Ventricle - fluid pocket in the brain (4 in all), that holds spinal fluid. Abnormal enlargement of the ventricles is called hydrocephalus.

© 2008 HCA - The Medical Center of Aurora, Aurora Colorado