Benign essential blepharospasm:  A rare disorder in which the muscles of the eyelids (orbiculares oculi) do not function properly, and that includes intermittent and involuntary contractions or spasms of the muscles around the eyes. Although the eyes themselves are unaffected, the patient may eventually become functionally blind because of an inability to open the eyelids. Benign essential blepharospasm is a form of dystonia, which is a group of neuromuscular disorders characterized by muscle spasms. More about dystonia.
Benign essential tremor:  A neurologic movement disorder characterized by involuntary fine rhythmic tremor of a body part or parts, primarily the hands and arms (upper limbs).  More about essential tremor.
Biopsy:  The removal of a small portion of tissue, usually for the purpose of pathological examination and diagnosis.
Bone graft:  Small piece(s) of extra bone that act as the "cement" for fusing vertebrae together.
Brachial plexus:  A network of nerves in the neck, passing under the collarbone and into the armpit. These nerves originate from the 5th, 6th, 7th and 8th cervical spinal nerves and the first 2 thoracic spinal nerves.
Bradykinesia:  Slowness in movement. More about movement disorders.
Brainstem:  The part of the central nervous system at the top of the spinal cord and the bottom of the brain; the brainstem controls most vital functions. More about brainstem tumors.
Brown-Sequard syndrome:

 The loss of sensation of touch, position, and movement on the side of a spinal cord lesion, with loss of pain sensation on the other side. The syndrome is caused by a lesion limited to one side of the spinal cord. More about spinal tumors.

Carcinoma:  Cancer; a malignant growth of epithelial or gland cells.
Carotid artery:  The large artery on either side of the neck that supplies most of the blood to the brain.
Carotid cavernous fistula (CCF):  An abnormal communication between the internal and external portions of the carotid arteries or any of their branches and the cavernous sinus.
Carotid sinus:  Slight dilatation on the common carotid artery at its bifurcation containing nerve cells sensitive to blood pressure. Stimulation can cause slowing of the heart, vasodilatation, and a fall in blood pressure.
Catheter:  A small tube used to inject a dye to see the blood vessels, similar to that used for looking at vessels in the heart.
Cauda equina (CES):  The bundle of long spinal nerve roots arising from the end of the spinal cord and filling the lower part of the spinal canal (from approximately the thoracolumbar junction down). These long nerves resemble a horse's tail (cauda equina).
Cavernous malformation (cav mal):  A rare type of vascular malformation. More on cavernous malformations.
Central nervous system (CNS):  The brain and the spinal cord.
Cerebellum:  The lower part of the brain, which is beneath the posterior portion of the cerebrum and regulates unconscious coordination of movement.
Cerebrospinal fluid (CSF):  A clear, water-like fluid that circulates around the brain and spinal cord.
Cerebrum:  The principal portion of the brain, which occupies the major portion of the interior of the skull and controls conscious movement, sensation, and thought. Separated into right and left hemispheres.
Cervical spine:  The upper spine/neck; the cervical spine is made up of seven vertebrae.

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