Vacuolation of myelin in the posterior and lateral columns of the primarily thoracic spinal cord occurring in AIDS and resulting in paraparesis, sensory ataxia, and incontinence; resembles the myelopathy associated with vitamin B12 deficiency
Vagus nerve (cranial nerve X)
Nerve containing motor, sensory, and parasympathetic fibres; motor fibres originate from the dorsal motor nucleus of the vagus (to innervate the pharynx and the thoracic and abdominal viscera) and the nucleus ambiguous (to innervate the palate, pharynx, and larynx); sensory fibers originate in the nodose ganglion and mediate taste and sensation in the pharynx and thoracic and abdominal viscera
Caused by disruption in blood supply to the brain through the vascular system which in turn causes brain cells to die leading to dementia
Diseases affecting any of the vessels which carry blood (arteries, veins and capillaries)
Blood vessel constriction in response to irritative stimuli
Subacute or chronic condition following coma and consisting of return to wakefulness but apparent total lack of cognition
Four cerebrospinal fluid filled cavities (paired lateral, third, and fourth) deep with the brain that communicate with each other and with the central canal of the spinal cord and the subarachnoid space
Ventricular Septal Defect (VSD)
A hole in the muscle wall that separates the two chambers (ventricles) of the heart
Movement of the eyes in opposite directions so that images of an object are placed on both foveas and thus appear single
Vergence (dysconjugate eye movements)
Movement of both eyes in different directions at the same time; includes 2 types: convergence and divergence
Median region of the cerebellum lying between the cerebeller hemispheres
Version (conjugate eye movements)
Movement of both eyes in the same direction at the same time; includes 4 types: saccade, smooth pursuit, optokinetic nystagmus movements, and vestibulo-ocular response movements
The two arteries that travel up the back of the neck to the brain which, along with the two carotid arteries, supply all the blood to the brain
This is an abnormal sensation of movement which makes you feel as if either you or the room is spinning. It can be a symptom of either a stroke or a transient ischemic attack, although it is more commonly a symptom of a problem with the ear and balance
Vestibulocochlear nerve (cranial nerve VIII)
Sensory nerve carrying information from the semicircular canals, utricle, and saccule to mediate equilibrium and hearing
Descending pathway from vestibular nuclei in the brainstem to spinal inter- and motor neurons that causes contraction of many muscles in the trunk and limbs as the head moves in space, providing automatic anti-gravity control to maintain upright stance
Process by which adjacent or remote cortex may assume the function previously carried out by damaged cortex
Perivascular extensions of subarachnoid space
Measurement of the eye�s ability to distinguish details; typically expressed as a fraction in which the numerator (20) indicates that the subject is standing at 20 feet from a normal test object and the denominator is the distance from which a normal subject can read the same normal image .
A visual recognition disorder characterised by the inability to make sense of visual stimuli e.g. when familiar objects or people cannot be recognised. This is often due to damage, in posterior occipital and/or temporal lobe(s) of the brain.
Visual evoked potentials (VEP)
Series of waves that reflect sequential activation of neural structures along the visual pathways following checkerboard stimulation; most useful in screening for optic nerve pathology (e.g., optic neuritis) and less useful in postchiasmatic disorders
Entire area visible to an eye that is fixating straight ahead
Visual field-cut/field impairment
Loss of sight in a particular area of the visual field, of which the person may be unaware. With a field impairment to one side a person is likely to walk into doorposts or ignore friends on that side of the room. A lower visual field impairment may cause difficulty in walking without tripping over things on the ground, reading from the lower part of pages, or seeing food on the edge of the plate. Lenses that incorporate a prism may be beneficial.
The capacity of the brain to retain visual imagery. Usually the brain records information and data better when it is perceived visually.
Where a person fails to pay attention to their body or environment on the affected side. This more frequently affects attention to the left side. A person with neglect may no longer wash that side of their face and may experience difficulty navigating even in familiar places. Also known as hemispatial agnosia or hemispatial neglect.
The ability to interpret visible information reaching the eyes, which is then made available for planning and action. The resulting perception is also known as eyesight, sight or vision.