STUDY - Technical - New Dacian's Medicine
Nystagmus
(Classical / Allopathic Medicine)
Nystagmus refers
to the involuntary oscillations of one or, more commonly, both
eyeballs. These oscillations are usually rhythmic and may be
horizontal, vertical, or rotary. They may be transient or
sustained and may occur spontaneously or on deviation or
fixation of the eyes. Although nystagmus is fairly easy to
identify, the patient may be unaware of it unless it affects
his vision.
Nystagmus may be
classified as jerk or pendular. Jerk nystagmus
(convergence-retraction, downbeat, and vestibular) has a fast
component and then a slow, perhaps unequal, corrective
component in the opposite direction. Pendular nystagmus
consists of horizontal (pendular) or vertical (seesaw)
oscillations that are equal in both directions and resemble
the movements of a clock's pendulum. (See Classifying
nystagmus.)
Classifying
nystagmus
Jerk nystagmus
Convergence-retraction nystagmus refers to the irregular jerking of the eyes back into the orbit during an upward gaze. It can indicate midbrain tegmental damage.
Downbeat nystagmus refers to the irregular downward jerking of the eyes during the downward gaze. It can signal lower medullary damage.
Vestibular nystagmus, the horizontal or rotary movement of the eyes, suggests vestibular disease or cochlear dysfunction.
Pendular nystagmus
Horizontal, or pendular, nystagmus refers to oscillations of equal velocity around a center point. It can indicate congenital loss of visual acuity or multiple sclerosis.
Vertical, or seesaw, nystagmus is the rapid seesaw movement of the eyes: one eye appears to rise while the other appears to fall. It suggests an optic chiasm lesion.
Nystagmus is considered a supranuclear ocular palsy - that is, it results from pathology in the visual perceptual area, vestibular system, cerebellum, or brain stem rather than in the extraocular muscles or in cranial nerve III, IV, or VI. Its causes are varied and include brain stem or cerebellar lesions, multiple sclerosis, encephalitis, labyrinthine disease, and drug toxicity. Occasionally, nystagmus is entirely normal; it's also considered a normal response in the unconscious patient during the doll's eye test (oculocephalic stimulation) or the cold caloric water test (oculovestibular stimulation).
Jerk nystagmus
Convergence-retraction nystagmus refers to the irregular jerking of the eyes back into the orbit during an upward gaze. It can indicate midbrain tegmental damage.
Downbeat nystagmus refers to the irregular downward jerking of the eyes during the downward gaze. It can signal lower medullary damage.
Vestibular nystagmus, the horizontal or rotary movement of the eyes, suggests vestibular disease or cochlear dysfunction.
Pendular nystagmus
Horizontal, or pendular, nystagmus refers to oscillations of equal velocity around a center point. It can indicate congenital loss of visual acuity or multiple sclerosis.
Vertical, or seesaw, nystagmus is the rapid seesaw movement of the eyes: one eye appears to rise while the other appears to fall. It suggests an optic chiasm lesion.
Nystagmus is considered a supranuclear ocular palsy - that is, it results from pathology in the visual perceptual area, vestibular system, cerebellum, or brain stem rather than in the extraocular muscles or in cranial nerve III, IV, or VI. Its causes are varied and include brain stem or cerebellar lesions, multiple sclerosis, encephalitis, labyrinthine disease, and drug toxicity. Occasionally, nystagmus is entirely normal; it's also considered a normal response in the unconscious patient during the doll's eye test (oculocephalic stimulation) or the cold caloric water test (oculovestibular stimulation).
HISTORY:
Ask the patient whether he's aware of his nystagmus and, if he is, how long he has had it.
Ask the patient if the nystagmus occurs intermittently or continuously.
Ask the patient if the nystagmus affects his vision.
Review the patient's medical history, noting especially recent infections (especially of the ear or respiratory tract), head trauma, cancer, and stroke. Also, ask the patient if there's a family history of stroke.
Assess the patient for associated signs and symptoms, such as vertigo, dizziness, tinnitus, nausea or vomiting, numbness, weakness, bladder dysfunction, and fever.
Ask the patient whether he's aware of his nystagmus and, if he is, how long he has had it.
Ask the patient if the nystagmus occurs intermittently or continuously.
Ask the patient if the nystagmus affects his vision.
Review the patient's medical history, noting especially recent infections (especially of the ear or respiratory tract), head trauma, cancer, and stroke. Also, ask the patient if there's a family history of stroke.
Assess the patient for associated signs and symptoms, such as vertigo, dizziness, tinnitus, nausea or vomiting, numbness, weakness, bladder dysfunction, and fever.
PHYSICAL
ASSESSMENT:
Assess the patient's level of consciousness and vital signs. Be alert for signs and symptoms of increased intracranial pressure, such as pupillary changes, drowsiness, elevated systolic pressure, and altered respiratory pattern.
Assess nystagmus fully by testing extraocular muscle function. Ask the patient to focus straight ahead and then to follow your finger up, down, and in an “X” across his face. Note when nystagmus occurs as well as its velocity and direction.
Test reflexes, motor and sensory function, and the cranial nerves.
Assess the patient's level of consciousness and vital signs. Be alert for signs and symptoms of increased intracranial pressure, such as pupillary changes, drowsiness, elevated systolic pressure, and altered respiratory pattern.
Assess nystagmus fully by testing extraocular muscle function. Ask the patient to focus straight ahead and then to follow your finger up, down, and in an “X” across his face. Note when nystagmus occurs as well as its velocity and direction.
Test reflexes, motor and sensory function, and the cranial nerves.
SPECIAL
CONSIDERATIONS:
Jerk nystagmus may result from barbiturate, phenytoin, or carbamazepine toxicity or from alcohol intoxication.
Jerk nystagmus may result from barbiturate, phenytoin, or carbamazepine toxicity or from alcohol intoxication.
PEDIATRIC
POINTERS:
In children, pendular nystagmus may be idiopathic or it may result from early impaired vision associated with optic atrophy, albinism, congenital cataracts, or severe astigmatism.
In children, pendular nystagmus may be idiopathic or it may result from early impaired vision associated with optic atrophy, albinism, congenital cataracts, or severe astigmatism.
PATIENT
COUNSELING:
Instruct the patient on what to expect from diagnostic testing, which may include electronystagmography and cerebral computed tomography scans.
Instruct the patient on what to expect from diagnostic testing, which may include electronystagmography and cerebral computed tomography scans.
Bibliography:
1. Rapid Assessment, A
Flowchart Guide to Evaluating Signs & Symptoms, Lippincott
Williams & Wilkins, 2004.
2. Professional Guide to
Signs and symptoms, Edition V, Lippincott
Williams & Wilkins, 2007.
3. Guide to common symptoms,
Edition V, McGraw - Hill, 2002.