How do you calculate directional preponderance?

Directional preponderance — right-beating – left-beating/total. It should be 35% or less. There is little if any clinical value in DP. Unilateral paresis or RVR (relative vestibular reduction), RVR = (RC+RW-LC-LW)/TR.

What is unilateral caloric weakness?

Unilateral weakness is indicative of a peripheral vestibular lesion that involves the nerve or end-organ on the side of the weakness. In many clinics, a UW greater than 25% is significant. Average caloric responses of 6 degrees per second or less are consistent with a bilateral weakness.

What causes directional preponderance?

At low stimulus levels, bias is the major cause of directional preponderance. Over time, directional preponderance gradually abates due to the process of vestibular compensation.

How is caloric test measured?

During caloric stimulation, cold and warm water are placed into your ear canals and your reaction is monitored. Other names for caloric stimulation are caloric reflex test, cold water calorics, and warm water calorics.

What does directional preponderance mean?

Directional Preponderance (DP) was firstly defined by Jongkess (1) as a tendency to a greater intensity of nystagmus to a certain direction in comparison to another. According to some researches, DP is more frequent noticed in patients who present spontaneous nystagmus in the same direction (3,4).

What is spontaneous nystagmus?

Spontaneous nystagmus denotes movement of the eyes without a cognitive, visual or vestibular stimulus. Most commonly spontaneous nystagmus is caused by a vestibular imbalance. Normally, both vestibular nerves fire at a tonic rate. The two nerves input is subtracted centrally.

What is a unilateral weakness?

A Unilateral Vestibular Loss (UVL) is a one-sided weakness in the balance mechanism of the inner ear. The weakness can occur suddenly or gradually, depending on the pathology or situation that has caused the weakness.

Is vestibular neuritis unilateral?

Vestibular neuritis (VN) is an acute disorder characterised by vertigo, nausea, vomiting and imbalance following sudden unilateral loss of peripheral vestibular function (1). Recovery is through peripheral and central vestibular compensation (2).

What is meant by directional preponderance?

INTRODUCTION. Directional Preponderance (DP) was firstly defined by Jongkess (1) as a tendency to a greater intensity of nystagmus to a certain direction in comparison to another. According to some researches, DP is more frequent noticed in patients who present spontaneous nystagmus in the same direction (3,4).

What is unilateral canal paresis?

Unilateral loss of horizontal semicircular canal function, termed canal paresis, is an important finding in dizzy patients. Using magnetic search coils to measure head and eye movement, we have validated this sign in 12 patients who had undergone unilateral vestibular neurectomy.

What is a positive caloric test?

Caloric stimulation is a test that uses differences in temperature to diagnose damage to the acoustic nerve. This is the nerve that is involved in hearing and balance. The test also checks for damage to the brain stem.

What causes nystagmus?

What causes nystagmus? Jerk nystagmus usually results from diseases affecting the inner ear balance mechanisms or the back part of the brain (brainstem or cerebellum). Pendular nystagmus can result from brain diseases such as multiple sclerosis, but can be a congenital problem as well.

What is the directional preponderance value for DP?

A directional preponderance value of 30% or greater is generally used to suggest the presence of a DP (Figure 5). DP is most often seen in acute impairments in which spontaneous nystagmus is present secondary to an uncompensated unilateral vestibular deficit.

What does a directional preponderance mean on a caloric test?

A directional preponderance indicates that the nystagmus response is greater in one direction as compared to the other. Directional preponderance indicates an asymmetry in the cumulative right and left beating nystagmus from both labyrinths. The caloric responses have a moderate range of asymmetry before being classed as abnormal.

What does directional preponderance mean in the nystagmus?

Directional preponderance indicates an asymmetry in the cumulative right and left beating nystagmus from both labyrinths. The caloric responses have a moderate range of asymmetry before being classed as abnormal. This is because the slow phase velocity of nystagmus is variable depending on the aural irrigation,…