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Pathologic nystagmus is a form of involuntary eye movement
Eye movement

Eye movement may refer to:* Eye movement , the voluntary or involuntary movement of the eyes* Eye movement in reading, the method in which eye movement assimilates written language...
. It is characterized by alternating smooth pursuit in one direction and saccadic movement in the other direction.

When nystagmus occurs without filling its normal function, it is pathologic (deviating from the healthy or normal condition). Pathological nystagmus is the result of damage to one or more components of the vestibular system
Vestibular system

The vestibular system, which contributes to our balance and our sense of spatial orientation, is the sensory system that provides the dominant input about movement and equilibrioception....
, including the semicircular canals, otolith organs, and the vestibulocerebellum.

Pathological nystagmus generally causes a degree of vision impairment, although the severity of such impairment varies widely.






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Pathologic nystagmus is a form of involuntary eye movement
Eye movement

Eye movement may refer to:* Eye movement , the voluntary or involuntary movement of the eyes* Eye movement in reading, the method in which eye movement assimilates written language...
. It is characterized by alternating smooth pursuit in one direction and saccadic movement in the other direction.

When nystagmus occurs without filling its normal function, it is pathologic (deviating from the healthy or normal condition). Pathological nystagmus is the result of damage to one or more components of the vestibular system
Vestibular system

The vestibular system, which contributes to our balance and our sense of spatial orientation, is the sensory system that provides the dominant input about movement and equilibrioception....
, including the semicircular canals, otolith organs, and the vestibulocerebellum.

Pathological nystagmus generally causes a degree of vision impairment, although the severity of such impairment varies widely. Sometimes it is the other way around — many blind
Blindness

Blindness is the condition of lacking visual perception due to physiological or neurological factors.Various scales have been developed to describe the extent of vision loss and define "blindness." Total blindness is the complete lack of form and visual light perception and is clinically recorded as "NLP," an abbreviation for "no ligh...
 people have nystagmus, which is one reason that some wear dark glasses.

Prevalence

Nystagmus is a relatively common clinical condition, affecting one in every 5,000 to 10,000 individuals. One survey in Oxfordshire, England, identified one in every 670 children by the age of two as manifesting nystagmus.

Variations

  • Peripheral nystagmus occurs as a result of either normal or diseased functional states of the vestibular system and may combine a rotational component with vertical or horizontal eye movements and may be spontaneous, positional, or evoked.
    • Positional nystagmus occurs when a person's head is in a specific position. An example of disease state in which this occurs is Benign paroxysmal positional vertigo
      Benign paroxysmal positional vertigo

      Benign paroxysmal positional vertigo or benign paroxysmal vertigo is a disorder caused by problems in the inner ear. Its symptoms are repeated episodes of positional vertigo, that is, of a spinning sensation caused by changes in head position....
       (BPPV).
    • Gaze Induced nystagmus occurs or is exacerbated as a result of changing one's gaze toward or away from a particular side which has an affected vestibular apparatus.
    • Post rotational nystagmus occurs after an imbalance is created between a normal side and a diseased side by stimulation of the vestibular system by rapid shaking or rotation of the head.
    • Spontaneous nystagmus is nystagmus that occurs randomly, regardless of the position of the patient's head.
  • Central nystagmus occurs as a result of either normal or abnormal processes not related to the vestibular organ. For example, lesions of the midbrain or cerebellum can result in up- and down-beat nystagmus.


Causes

The cause for pathological nystagmus may be congenital, idiopathic
Idiopathic

Idiopathic is an adjective used primarily in medicine meaning arising spontaneously or from an obscure or unknown cause. From Greek ?d???, idios + p????, pathos , it means approximately "a disease of its own kind."...
, or secondary to a pre-existing neurological disorder; or it may be induced temporarily by disorientation (such as on roller coaster rides) or certain drug
Psychoactive drug

A psychoactive drug or psychotropic substance is a chemical substance that acts primarily upon the central nervous system where it alters brain function, resulting in temporary changes in perception, mood , consciousness and behaviour....
s (alcohol
Alcohol

In chemistry, an alcohol is any organic compound in which a hydroxyl Functional group is bound to a carbon atom of an alkyl or substituted alkyl group....
 and other central nervous system
Central nervous system

The central nervous system is the part of the nervous system that functions to coordinate the activity of all parts of the bodies of multicellular organisms....
 depressants and stimulants, such as lithium salts, phenytoin
Phenytoin

Phenytoin sodium is a commonly used antiepileptic. Phenytoin acts to dampen the unwanted, runaway brain activity seen in seizure by reducing electrical conductance among brain cells by stabilizing the inactive state of voltage gated sodium channels....
, and MDMA).

Congenital
Congenital nystagmus occurs more frequently than acquired nystagmus. It can be insular or accompany other disorders (such as micro-ophthalmic anomalies or Down's Syndrome). Congenital nystagmus itself is usually mild and non-progressive. The affected persons are not normally aware of their spontaneous eye movements but vision can be impaired depending on the severity of the movements.
  • Infantile:
  • Idiopathic
    Idiopathic

    Idiopathic is an adjective used primarily in medicine meaning arising spontaneously or from an obscure or unknown cause. From Greek ?d???, idios + p????, pathos , it means approximately "a disease of its own kind."...
  • Albinism
    Albinism

    Albinism is a form of hypopigmentation congenital disorder, characterized by a partial or total lack of melanin Biological pigment in the eyes, skin and hair ....
  • Aniridia
    Aniridia

    Aniridia is a rare congenital condition characterized by the underdevelopment of the eye's iris . This usually occurs in both eyes. It is associated with poor development of the retina at the back of the eye preventing normal vision development....
  • Leber's congenital amaurosis
    Leber's congenital amaurosis

    Leber's congenital amaurosis is a rare heredity List of eye diseases and disorders that appears at congenital or in the first few months of life, and affects around 1 in 80,000 of the population....
  • Bilateral optic nerve hypoplasia
    Optic nerve hypoplasia

    Optic nerve hypoplasia is a medical condition that results in underdevelopment of the optic nerves....
  • Bilateral congenital cataracts
  • Rod monochromatism
  • Optic nerve
    Optic nerve

    The optic nerve, also called cranial nerve II, transmits visual information from the retina to the brain....
     or macula
    Macula

    The macula or macula lutea is an oval-shaped highly pigmented yellow spot near the center of the retina of the human eye. It has a diameter of around 5 mm and is often histologically defined as having two or more layers of ganglion cells....
    r disease
  • Persistent tunica vasculosa lentis
    Persistent tunica vasculosa lentis

    Persistent tunica vasculosa lentis is a congenital ocular anomaly. Also known as persistent hyperplastic primary vitreous .* It is a developmental disorder of the vitreous....


  • Latent nystagmus
  • Nystagmus blockage syndrome


X-linked infantile nystagmus is associated with FRMD7
FRMD7

FERM domain containing 7, also known as FRMD7, is a human gene.ReferencesFurther reading...
.

Acquired

Diseases
Some of the diseases that present nystagmus as a pathological sign:
  • Benign Paroxysmal Positional Vertigo
    Benign paroxysmal positional vertigo

    Benign paroxysmal positional vertigo or benign paroxysmal vertigo is a disorder caused by problems in the inner ear. Its symptoms are repeated episodes of positional vertigo, that is, of a spinning sensation caused by changes in head position....
     
  • Head trauma
  • Stroke
    Stroke

    A stroke is the rapidly developing loss of brain function due to a disturbance in the blood supply to the brain. According to the National Stroke Association, a "stroke" occurs when a blood clot blocks and artery or a blood vessel breaks, interrupting blood flow to an area of the brain....
     (the most common cause in older people)
  • Ménière's disease
    Ménière's disease

    M?ni?re's disease is a disorder of the inner ear that can affect Hearing and balance. It is characterized by episodes of dizziness and tinnitus and progressive hearing loss, usually in one ear....
     and other balance disorder
    Balance disorder

    A balance disorder is a disturbance that causes an individual to feel unsteady, giddy, woozy, or have a sensation of movement, spinning, or floating....
    s
  • Multiple sclerosis
    Multiple sclerosis

    Multiple sclerosis is an autoimmune disease in which the immune system attacks the central nervous system, leading to demyelinating disease. Disease onset usually occurs in young adults, and it is more common in females....
  • Brain tumor
    Brain tumor

    A brain tumor is an abnormal growth of cells within the brain or inside the skull, which can be cancerous or non-cancerous .It is defined as any cranium tumor created by abnormal and uncontrolled Mitosis, normally either in the brain itself , in the cranial nerves , in the brain envelopes , skull, pituitary and pineal gland, or spread from...
    s
  • Wernicke-Korsakoff syndrome
    Wernicke-Korsakoff syndrome

    Wernicke-Korsakoff syndrome is a manifestation of thiamine deficiency, or beri-beri. This is usually secondary to alcohol abuse. It mainly causes vision changes, ataxia and impaired memory....
  • Encephalopathy
    Encephalopathy

    Encephalopathy /?n?s?f?'l?p??i/ literally means Disorder or disease of the brain. ...
  • Lateral medullary syndrome
    Lateral medullary syndrome

    Lateral medullary syndrome is a disease in which the patient has difficulty with swallowing or speaking or both owing to one or more patches of dead tissue caused by interrupted blood supply to parts of the brain....
  • Aniridia
    Aniridia

    Aniridia is a rare congenital condition characterized by the underdevelopment of the eye's iris . This usually occurs in both eyes. It is associated with poor development of the retina at the back of the eye preventing normal vision development....
  • Optic nerve hypoplasia
    Optic nerve hypoplasia

    Optic nerve hypoplasia is a medical condition that results in underdevelopment of the optic nerves....
  • Albinism
    Albinism

    Albinism is a form of hypopigmentation congenital disorder, characterized by a partial or total lack of melanin Biological pigment in the eyes, skin and hair ....
  • Noonan syndrome
    Noonan syndrome

    Noonan Syndrome is a relatively common congenital genetic condition which affects both males and females equally. It used to be referred to as the male version of Turner's syndrome; however, the genetic causes of Noonan syndrome and Turner syndrome are distinct....
  • Pelizaeus-Merzbacher disease
    Pelizaeus-Merzbacher disease

    Pelizaeus-Merzbacher disease is a rare central nervous system disorder in which coordination, motor abilities, and intellectual function are delayed to variable extents....
  • Superior canal dehiscence syndrome
    Superior canal dehiscence syndrome

    Superior canal dehiscence syndrome is a rare medical condition of the inner ear, first described in 1998 by of Johns Hopkins University Hospital, Baltimore, USA,...
  • Tullio phenomenon
    Tullio phenomenon

    Tullio phenomenon, sound-induced vertigo, dizziness, nausea and/or eye movements was first described in 1929 by the Italian biologist Prof. Pietro Tullio....
  • Horner's Syndrome
    Horner's syndrome

    Horner's syndrome or Horner syndrome is a clinical syndrome caused by damage to the sympathetic nervous system. It is also known by the names Bernard-Horner syndrome or oculosympathetic palsy....


Toxic/metabolic
Nystagmus from toxic or metabolic reasons could be the result of the following:
  • Alcohol intoxication (see above)
  • Lithium
    Lithium pharmacology

    Lithium pharmacology refers to use of the lithium ion, Li+, as a drug. A number of chemical salts of lithium are used medically as a mood stabilizer Medication, primarily in the treatment of bipolar disorder, where they have a role in the treatment of Clinical depression and particularly of mania, both acutely and in the long term....
  • Barbiturates
  • SSRIs
    Selective serotonin reuptake inhibitor

    Selective serotonin reuptake inhibitors or serotonin-specific reuptake inhibitor are a class of antidepressants used in the treatment of Clinical depression, anxiety disorders, and some personality disorders....
  • Phenytoin
    Phenytoin

    Phenytoin sodium is a commonly used antiepileptic. Phenytoin acts to dampen the unwanted, runaway brain activity seen in seizure by reducing electrical conductance among brain cells by stabilizing the inactive state of voltage gated sodium channels....
     (Dilantin)
  • Salicylates
  • Benzodiazepines
  • Lysergic acid diethylamide (LSD)
  • Phencyclidine
    Phencyclidine

    Phencyclidine , also known as angel dust, is a dissociative drug formerly used as an anesthesia agent, exhibiting hallucinogenic and neurotoxic effects....
     (PCP)
  • Ketamine
    Ketamine

    Ketamine is a drug used in human and veterinary medicine developed by Parke-Davis in 1962. Its hydrochloride salt is sold as Ketanest, Ketaset, and Ketalar....
  • Other anticonvulsants or sedatives
  • Methylenedioxymethamphetamine
    Methylenedioxymethamphetamine

    MDMA , most commonly known today by the street name ecstasy , is a semisynthetic member of the amphetamine class of psychoactive drugs, a subclass of the phenethylamines.....
  • Wernicke's encephalopathy
    Wernicke's encephalopathy

    Wernicke encephalopathy is a syndrome characterised by ataxia, ophthalmoplegia, confusion, and impairment of short-term memory.It is caused by lesions in the medial thalamic nuclei, mammillary bodies, periaqueductal and periventricular brainstem nuclei, and superior cerebellar vermis, often resulting from inadequate intake or absorption of t...
  • Thiamine
    Thiamine

    'Thiamine', or 'thiamin', sometimes called aneurin, is a water-soluble vitamin of the B complex , whose phosphate derivatives are involved in many cellular processes....
     deficiency


Central nervous system disorders
If the pathologic nystagmus is based in the central nervous system
Central nervous system

The central nervous system is the part of the nervous system that functions to coordinate the activity of all parts of the bodies of multicellular organisms....
 (CNS), such as with a cerebellar
Cerebellum

The cerebellum is a region of the brain that plays an important role in the integration of perception, coordination and motoneuron control. In order to coordinate motor control, there are many neural pathways linking the cerebellum with the cerebrum motor cortex and the spinocerebellar tract ....
 problem, the nystagmus can be in any direction including horizontal. Purely vertical nystagmus is usually central in origin.

Causes include e.g.:
  • Thalamic
    Thalamus

    The thalamus is a pair and symmetric part of the brain. It constitutes the main part of the diencephalon....
     hemorrhage
  • Tumor
    Tumor

    A tumor or tumour is the name for a swelling or lesion formed by an abnormal growth of cells . Tumor is not synonymous with cancer. A tumor can be Benign neoplasm, Carcinoma in situ or malignant, whereas cancer is by definition malignant....
  • Stroke
    Stroke

    A stroke is the rapidly developing loss of brain function due to a disturbance in the blood supply to the brain. According to the National Stroke Association, a "stroke" occurs when a blood clot blocks and artery or a blood vessel breaks, interrupting blood flow to an area of the brain....
  • Trauma
  • Multiple sclerosis
    Multiple sclerosis

    Multiple sclerosis is an autoimmune disease in which the immune system attacks the central nervous system, leading to demyelinating disease. Disease onset usually occurs in young adults, and it is more common in females....
  • Cerebellar ataxia
    Cerebellar ataxia

    Cerebellar ataxia is a form of ataxia originating in the cerebellum.Romberg's test can be used to distinguish cerebellar ataxia from other forms of ataxia....


Other causes
  • Vestibular Pathology (Ménière's disease
    Ménière's disease

    M?ni?re's disease is a disorder of the inner ear that can affect Hearing and balance. It is characterized by episodes of dizziness and tinnitus and progressive hearing loss, usually in one ear....
    , SCDS (superior canal dehiscence syndrome
    Superior canal dehiscence syndrome

    Superior canal dehiscence syndrome is a rare medical condition of the inner ear, first described in 1998 by of Johns Hopkins University Hospital, Baltimore, USA,...
    ), BPPV, Labyrinthitis
    Labyrinthitis

    Labyrinthitis is a balance disorder. It is an inflammatory process affecting the Labyrinth s that house the vestibular system of the inner ear....
    )
  • Trochlear nerve
    Trochlear nerve

    The trochlear nerve is a motor nerve that innervates a single muscle: the superior oblique muscle of the eye. An older name is pathetic nerve, which refers to the dejected appearance that is characteristic of patients with fourth nerve palsies....
     malfunction
  • Non-physiologic


Diagnosis

Nystagmus is very noticeable but little recognised. Nystagmus can be clinically investigated by using a number of non-invasive
Non-invasive (medical)

The term non-invasive in medicine has two meanings:* A medical procedure is strictly defined as non-invasive when no break in the skin is created and there is no contact with the mucosa, or skin break, or internal body cavity beyond a natural or artificial body orifice....
 standard tests. The simplest one is Caloric reflex test
Caloric reflex test

In medicine, the caloric reflex test is a test of the vestibulo-ocular reflex that involves irrigating cold or warm water or air into the external auditory canal....
, in which one external auditory meatus
Ear

The ear is the sense organ that detects sounds. The vertebrate ear shows a common biology from fish to humans, with variations in structure according to order and species....
 is irrigated with warm or cold water. The temperature gradient provokes the stimulation of the vestibulocochlear nerve
Vestibulocochlear nerve

The vestibulocochlear nerve is the eighth of twelve cranial nerves, and is responsible for transmitting sound and equilibrium information from the inner ear to the brain....
 and the consequent nystagmus.

The resulting movement of the eyes may be recorded and quantified by special devices called electronystagmograph (ENG), a form of electrooculography
Electrooculography

Electrooculography is a technique for measuring the resting potential of the retina. The resulting signal is called the electrooculogram. The main applications are in ophthalmology diagnosis and in recording eye movements....
 (an electrical method of measuring eye movements using external electrodes), or even less invasive devices called videoonystagmograph (VNG), a form of videooculography(VOG) (a video-based method of measuring eye movements using external small cameras built into head masks). Special swinging chairs with electrical controls are also used in this test to induce rotatory nystagmus.

Treatment

Congenital nystagmus has traditionally been viewed as non-treatable, but medications have been discovered in recent years that show promise in some patients. In 1980, researchers discovered that a drug called baclofen
Baclofen

Baclofen is a derivative of gamma-aminobutyric acid primarily used to treat spasticity.It is an agonist specific to mammalian but not fruit fly GABA B receptors....
 could effectively stop periodic alternating nystagmus. Subsequently, gabapentin
Gabapentin

Gabapentin is a Gamma-aminobutyric_acid analogue. It was originally developed for the treatment of epilepsy, and currently, gabapentin is widely used to relieve pain, especially neuropathic pain....
, an anticonvulsant, was found to cause improvement in about half the patients who received it to relieve symptoms of nystagmus. Other drugs found to be effective against nystagmus in some patients include memantine
Memantine

Memantine is the first in a novel class of Alzheimer's disease medications acting on the glutamatergic system by blocking NMDA glutamate receptors....
, levetiracetam
Levetiracetam

Levetiracetam is an anticonvulsant medication used to treat epilepsy. It is S- enantiomer of etiracetam, structurally similar to the prototypical nootropic drug piracetam....
, 3,4-diaminopyridine, 4-aminopyridine
4-Aminopyridine

4-Aminopyridine is an organic compound with the Chemical formula H2NC5H4N. The molecule is one of the three isomeric amines of pyridine....
, and acetazolamide
Acetazolamide

Acetazolamide, sold under the trade name Diamox, is a carbonic anhydrase inhibitor that is used to treat glaucoma, epileptic seizures, benign intracranial hypertension , altitude sickness, cystinuria, and dural ectasia....
. Several therapeutic approaches, such as contact lenses, drugs, surgery
Surgery

Surgery is a medical specialty that uses operative manual and instrumental techniques on a patient to investigate and/or treat a pathological condition such as disease or injury, to help improve bodily function or appearance, or sometimes for some other reason....
, and low vision
Low vision

Low vision is a subspecialty within the professions of optometry and ophthalmology and opticianry dealing with individuals who have less than normal vision even with the most accurate conventional prescription available....
 rehabilitation
Rehabilitation (neuropsychology)

Rehabilitation of sensory and cognitive function typically involves methods for retraining neural pathways or training new neural pathways to regain or improve neurocognitive functioning that has been diminished by disease or physical traumatic injury....
 have also been proposed.

Clinical trials of a surgery to treat nystagmus (known as tenotomy) concluded in 2001. Tenotomy is being performed regularly at the University of Pittsburgh Children's Hospital and by a handful of surgeons around the world. The surgery developed by Louis F. Dell'Osso Ph.D aims to reduce the eye shaking (oscillations), which in turn tends to improve visual acuity.

Research


Several universities are researching nystagmus and are looking for volunteers to take part in research activities.



See also

  • Optokinetic nystagmus


External links

  • — US-based support organisation
  • — UK-based support organisation
  • — a teenager's experiences of nystagmus and a friendly forum


See also

  • Physiologic nystagmus
    Physiologic nystagmus

    Physiologic nystagmus is a form of involuntary eye movement that is part of the vestibulo-ocular reflex . It is characterized by alternating smooth pursuit in one direction and saccadic movement in the other direction....