UPBEATING NYSTAGMUS

Timothy C. Hain, MD • Page last modified: September 19, 2022

VIDEO Video of upbeating nystagmus due to Wernicke's encephalopathy.

Upbeating nystagmus describes an eye condition in which the eyes drift downward and make upward corrective movements (beats). Here we are mainly discussing upbeating nystagmus that occurs in persons who are sitting upright, and that have their eyes in the center (primary position).

For those who like to get to the meat quickly, there is usually not very much to learn from weak upbeating nystagmus, but strong upbeating nystagmus is usually caused by brainstem damage.

Upbeating nystagmus is shown on the bottom panel of the figure to the left.

UBN is uncommon. At Chicago Dizziness and Hearing, we have only 30 patients with UBN out of a total of about 30,000 "dizzy" patients. This suggests that UBN is uncommon, even when patients are observed with very sensitive methods. Of 20 of these patients, 13/20 were women, and the average age was 46. Most of these patients were diagnosed with migraine. Migraine can cause nearly any nystagmus. This is probably because migraine is a polygenetic disorder, and the amalgamation of many individual conditions.

Upbeat nystagmus is also found in smokers as a side effect of nicotine, in persons with alcohol intoxication (Fetter et al, 1999) and as a side effect of medications. Some of the SSRI type antidepressents seem to be associated with upbeating nystagmus. This is commonly seen with venlafaxine as well. This has not been reported in the literature (as yet).

UBN can be found occasionally in patients with BPPV, even upright. This is attributed to cupulolithiasis.

These benign associations of UBN are far more common than serious brainstem disease.

UBN in migraine pateint Upbeating nystagmus is shown on the bottom of both the spontaneous nystagmus and gaze test, in this patient with vestibular migraine.

Common causes of UBN, usually suppressed by fixation:

 

Uncommon causes of UBN, which may be visible with fixation

While cancer is a very rare cause of UBN, and we have encountered it once in the last 10 years. It should not be your first thought.

UBN

Upbeating Nystagmus in a patient with a renal mass. Recorded using an Micromedical Technology IR tracking system at Chicago Dizziness and Hearing. Image courtesy of Dr. Marcello Cherchi of Chicago Dizziness and Hearing

Strong primary position upbeat nystagmus has been described in lesions of the medulla, the ventral tegmentum, the anterior vermis of the cerebellum, and the adjacent brachium conjunctivum and midbrain (Shaikh et al, 2013). We have occasionally seen UBN in individuals with the Chiari malformation as well as in spinal cord lesions. These are rare occurences however. See below for more discussion about brainstem lesions.

UBN has been reported in association in specific disorders such as Wernicke's encephalopathy, multiple sclerosis, brainstem infarction and other lesions.

Wernickes causing UBN

Upbeating nystagmus may be rarely seen in persons with Wernicke's syndrome, precipitated by thiamine deficiency.

In the author's experience with a Wernicke's patient (only one of the 20 described above), the nystagmus has a peculiar increase on downgaze (one would expect the opposite). Presumably this would implicate the neural integrator which controls vertical gaze holding (i.e. in the midbrain). Wernickes is usually found in the context of severe thiamine deficiciency.

Video of upbeating nystagmus due to Wernicke's encephalopathy.

Brainstem lesions causing UBN:

While UBN is generally caused by midline lesions when in the brainstem, cases have been reported in unilateral medial midbrain lesions.

There are many reports of UBN caused by lesions in the lower medulla:

Hirose and others (1998) , UBN may be caused by a lesion in the nucleus intercalatus of Staderini, one of the three subnuclei of the perihypoglossal nucleus (others include the nucleus of Roller, the nucleus prepositus hypoglossi which performs neural integration for the horizontal oculomotor system). Meling et al (2020), reported UBN after resection of a brainstem cavernoma clear to the nucleus of Roller. Similarly, Adamec et al (2012) reported primary position UBN in a lesion of the nucleus intercalatus. Choi et al (2011) reported UBN from a lesion in the caudal central medulla.

There was also a reports of UBN in lateral medullary syndromes. (Lee et al, 2021)

There have been reports of UBN in pontine lesions (Chang et al, 2021).

Ranalli and Sharpe (1988) suggested that some forms of UBN were explained by disruption of the ventral tegmental pathway for the upward VOR (vestibulo-ocular reflex), causing imbalance in the vertical VOR.

 

Modulation of UBN by convergence:

Upbeat nystagmus can be modulated by convergence, changing into downbeat, when it occurs congenitally as well as when associated with Wernicke's. This has been reported by Cox and others (1981).

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