Nystagmus is an involuntary rhythmic movement of the eye, which can be broadly divided into two categories: Jerk nystagmus, also known as phasic nystagmus, and Pendular nystagmus.
The sharp jumping nystagmus can be seen as fast or slow nystagmus in two opposite directions, and the faster direction is usually specified as the direction of nystagmus. For example, if a patient’s nystagmus has a fast phase to the right and a slow phase to the left, the nystagmus is said to be to the right. This type of nystagmus is more common and most of the nystagmus that occurs in lesions of the vestibular organs and related fiber pathways is of this type.
Oscillatory nystagmus refers to the back and forth movement of the eye without any distinction between fast and slow phases. It is occasionally seen in patients with multiple sclerosis.
The direction of nystagmus movement can be horizontal, vertical or rotational. Sometimes nystagmus can be accompanied by head nodding or tremors, up and down bouncing of the eyelids, and in addition, patients with acquired nystagmus can feel the rotation of their surroundings and experience vertigo.
1, retinal or refractive media lesions: congenital cataract, chorioretinitis, central corneal opacity or refractive error resulting in juvenile amblyopia, although still preserving part of the vision, but because the eye can not be fixed gaze, can cause swinging nystagmus.
If you are in a poorly lit area for a long time and your eyes are not fixed, you may also develop a pendular nystagmus, which is called “occupational or miner’s” nystagmus, and may be accompanied by head tremor and blepharospasm.
2, congenital and familial nystagmus: the cause is unknown, usually occurs shortly after birth and continues throughout life. The form of inheritance is autosomal dominant or sex-linked recessive. The patient has a slight oscillatory tremor at rest, which increases regardless of the direction of movement, and may be accompanied by head vibration or nodding. Patients often suffer from other eye defects, such as albinism, astigmatism or amblyopia, and therefore have poor vision.
Nodding spasms are seen in infants and may be characterized by nodding, head nodding, and neck tilting. It usually begins at 4 to 12 months of age and resolves at 3 to 4 years of age. The nodding is vertical rather than left-right, and the frequency of nodding is not related to the frequency of nystagmus, so it can be differentiated from congenital nystagmus.
3, vestibular labyrinth lesion: sharp jumping nystagmus may appear, often accompanied by tinnitus, vertigo, nausea, vomiting, hearing loss, gait staggering and other symptoms.
The nystagmus can be subdivided into 1 to 3 degrees: the first degree of leftward nystagmus refers to the leftward nystagmus when looking to the left; the second degree of leftward nystagmus refers to the leftward nystagmus when looking to the left or directly in front; the third degree of leftward nystagmus can occur regardless of looking to the left, right or directly in front.
Acute lesions of the inner ear vagus can cause nystagmus to the opposite side; looking sideways or turning the head in the direction of the fast-phase nystagmus can lead to increased nystagmus.
Tremor caused by central lesions Tremor caused by peripheral lesions
Symptoms such as vertigo May or may not be present, usually mild Usually severe
Tremor direction Tremor can occur in multiple directions depending on the direction of gaze Tremor occurs in a constant single direction regardless of the direction of gaze
Tremor form Horizontal, rotational or vertical Horizontal or rotational
Tremor in both eyes may be asymmetrical, corresponding to simultaneous tremor
Tremor disappears when gaze is removed Tremor becomes stronger
Duration Longer Shorter
Long bundle signs Yes No
In subacute or chronic labyrinthine lesions, a subtle tremor toward the side of the lesion may occur with lateral gaze, but no tremor may occur due to central compensatory phenomena.
In peripheral lesions (vagus, eighth nerve), horizontal or rotational tremor usually occurs.
4, central lesions: central lesions can cause horizontal, rotational or vertical tremor, some people say that vertical tremor is characteristic of brainstem disease, but vertical tremor can also occur due to brainstem compression and distortion or antitussive drug intoxication. Sharp jumping tremor is the main cause.
Brainstem lesions often cause unilateral tremor, and vertical tremor is mostly caused by upward visualization and is commonly seen in pontine periaqueductal disease. Uplift tremor can occur in demyelinating or vascular lesions, tumors, Wernicke’s disease, medullary cavernous disease, and Arnold-Chiari malformation. Vertical tremor when looking downward is usually caused by lesions near the “foramen magnum”, such as Arnold-Chiari malformation.
Tumors of the pontocerebellar horn, such as auditory neuroma, can cause bilateral horizontal tremor, with the tremor more pronounced to the side of the disease. When a hot and cold test is performed, a reduced tremor response toward the lesion side is seen.
Nystagmus caused by cerebellar lesions has a fast phase toward the direction of gaze and a slow phase toward the position of the eye at rest. In unilateral cerebellar lesions, nystagmus can occur in both eyes and is most pronounced when the lesion is viewed laterally; it has been suggested that nystagmus may occur only when the fibers linking the cerebellopontine nucleus to the vestibule are disrupted. The most common cause is multiple sclerosis, while others include tumors, vascular lesions, Friedreich’s ataxia, and various hereditary ataxias.
Medial longitudinal tract lesions such as superior or inferior inter-nuclear ophthalmoplegia can cause nystagmus. Some cervical medullary lesions can cause nystagmus, such as cervical medullary tumors, spinal cord cavitation, and Arnold-Chiari malformation, and may also be associated with destruction of fibers in the medial longitudinal tract.
In vestibular nucleus lesions, irritant lesions cause ipsilateral tremor, while destructive lesions cause contralateral tremor.
5.Poisoning: Nystagmus caused by drug poisoning is usually horizontal, and its fast phase is in the direction of gaze. For example, nystagmus can often occur when alcohol, all sedatives (especially barbiturates), antispasmodics (phenytoin, paracetamol, carbamazepine), bromides, etc. are poisoned.
6. Hypochondriasis: when the patient engages in nystagmus under non-consciousness, the nystagmus may disappear. In addition to other features of hypochondriasis, patients may also have blepharospasm, polyoptic spasm, etc.
7. Rebound nystagmus: A sharp jumping nystagmus occurs when the patient looks sideways, and after about 20 seconds of fatigue, the eye returns to the central position, and then a reverse nystagmus occurs, followed by fatigue after a few seconds. This sign is caused by cerebellar degeneration.
8, seesaw tremor: one eye trembles upward and the other eye trembles downward. Occasionally, seesaw tremor may occur in people with pars plana or pars plana tumors that cause hemianopia on both temporal sides, in addition to third ventricle tumors and pontocerebral lesions.
9, Polyphthalmic tremor: Both eyes slowly rotate outward at the same time and then quickly retract inward, this rhythmical vibration is called polyphthalmic tremor. It is usually accompanied by other types of tremor or Parinaud’s syndrome, and may also be accompanied by posterior retraction tremor, eyelid movement, and polyphthalmic spasm. The lesion is located in the upper midbrain periaqueductal region and is mainly caused by vascular disease or tumors.
10, Posterior retractive tremor: When the patient tries to look upward, the eye vibrates back and forth, which is seen in lesions in the upper and lower midbrain thalamus.
11.Palatal nystagmus: In patients with palatal myoclonus, rotational or convergent nystagmus may occur when looking forward, called palatal nystagmus, the frequency of this nystagmus is the same as the myoclonic rhythm of palatal and pharyngeal muscles, caused by lesions of the central tegmental tract, inferior olivary nucleus or olivocerebellar tract, which can be caused by tumors, encephalitis or It can be caused by tumor, encephalitis or infarct lesions.
12, optokinetic nystagmus: Gazing at a continuously moving scene can cause nystagmus, which is a sharp jump, so there is a fast phase and a slow phase. Barany drum (with a long black and white strip) is rotating, and optokinetic tremor can also occur when looking at it, and this tremor disappears in blind people, so it can be used to identify patients who claim to be blind or fraud.
Optokinetic nystagmus is a brainstem reflex, not related to the vestibular nucleus. The cortical center is located in the supramarginal gyrus and the angular gyrus of the parietal lobe of the brain. If a lesion occurs on one side of the parietal lobe, the optokinetic tremor elicited by Barany’s drum shifting to that side is reduced or disappears; the tremor elicited by the drum shifting to the opposite side of the lesion is normal. Tumors, infarcts or demyelinating diseases of the upper brainstem can cause loss, slowing or irregularity of nystagmus.
13.Postural nystagmus: Nystagmus is caused by changes in posture or head position and is commonly associated with benign positional vertigo. Tumors in the posterior fossa, such as ventricular ventricular meningioma or medulloblastoma in children and metastases in adults, may cause nystagmus when the patient turns his head or flexes his head.
Postural nystagmus can occur in two types: a. Benign: lying down
a. Benign type: The tremor occurs ten to fifteen seconds after lying down and lasts about fifty seconds, with the tremor directed toward the lower ear. The tremor is accompanied by severe vertigo when it occurs.
b. Central type: The tremor appears immediately after lying down and continues as long as the patient remains supine. This type is often caused by tumors in the posterior cerebral fossa.
Other lesions of the brainstem (e.g., majority sclerosis) may also cause postural nystagmus.
Caloric nystagmus: The cold or hot water poured into the external auditory canal can also cause nystagmus, which is the caloric test. The results of the hot and cold tests are interpreted as follows.
a. Canal paresis: damage to the semicircular canal or the eighth nerve can cause a decrease or disappearance of the tremor produced by the hot and cold test in this ear. If the right vestibular apparatus is diseased, the nystagmus response is reduced whether hot or cold water is instilled in the right ear canal. Examples include Meniere’s disease, vestibular neuritis, and auditory neuroma.
b. Directional preponderance: A lesion of the vestibular nucleus on one side may reduce the nystagmus response to that side during the hot and cold tests. For example, if the right vestibular nucleus is damaged, the nystagmus caused by hot water in the right ear and cold water in the left ear will be reduced, and the nystagmus will mainly be directed to the left side, which is the left-side predominance. Therefore, in brainstem lesions, hot and cold tremor to the contralateral side is dominant; in posterior temporal lobe lesions, tremor to the same side as the lesion is dominant.
c. If vertical tremor or tremor of the two eyes do not correspond, the location of the lesion may be in the brainstem.
15. Other tremors or similar eye movements.
In patients with loss of consciousness from head injury, transient nystagmus can often occur after regaining consciousness and does not affect the prognosis, but if it happens to be fractured at the rock bone, persistent nystagmus may occur due to damage to the vagus or eighth cerebral nerve.
Nystagmus-like nystagmus jerks (Nystagmoid jerks): A mild nystagmus can often occur in normal subjects with extreme lateral gaze to either side (especially when fatigued). Nystagmus may also occur in extraocular muscle paralysis such as myasthenia gravis, but is usually unilateral. In amblyopia, the eyeballs sometimes appear to move in an uncorresponding manner, resembling nystagmus.
Opsoclonus: A rapid corresponding fluttering of the eyeballs that worsens with random movements or fixation, usually accompanied by myoclonus. Opsoclonus is most commonly seen in infants with acute myoclonic encephalopathy, but can also be seen in adults with encephalitis or encephalopathy. Malignant tumors that are latent in the body, such as neuroblastoma, may also cause ocular clonus.
Ocular bobbing: Agile, repetitive downward corresponding deviation of both eyes, occurring about two or three times a minute, may occur in comatose patients with lesions in the lower pontine brain.