What does pendular nystagmus?
Pendular nystagmus refers to the waveform of an involuntary eye movement. In pendular nystagmus the eye moves in sinusoidal trajectory, similar to that of a pendulum. Pendular nystagmus generally does not have a “fast phase” including a saccade, but is composed entirely of slow eye movements.
What is Upbeating nystagmus?
Upbeat nystagmus is a type of central vestibular nystagmus. It can be caused by lesions from the medulla to the midbrain. It usually increases in up gaze, but not on lateral gaze, and fixation does not dampen it.
Why does Postrotatory nystagmus occur?
postrotatory nystagmus A form of vestibular nystagmus that occurs when the body is rotated and then the rotation is stopped. If, while sitting upright in a chair that can be swiveled, the body is rapidly rotated to the right, the nystagmus during rotation has its slow component to the left.
What is the definition of pendular?
: being or resembling the movement of a pendulum.
What is downbeat nystagmus?
Downbeat nystagmus (DBN) is characterized by a pathologic upward drift of gaze followed by a corrective downward saccade. DBN is most apparent when the patient is instructed to look down or to either side. It is typically accompanied by oscillopsia, which may be severe.
What is upbeat and downbeat nystagmus?
Downbeat and upbeat nystagmus are the directional counterparts of a vestibular tone imbalance in the pitch plane. The close proximity of the areas that cause either upbeat or downbeat nystagmus in the medulla is consistent with occasional transitions between the two conditions.
What is posterior canal BPPV?
Posterior canal BPPV is the most common form of BPPV. This condition is caused by otoconia (also known as canaliths, crystals or rocks) and is characterized by brief (10-15 seconds) vertigo associated with changes in head position.
How do you classify nystagmus?
Classification of nystagmus may be organized by physiologic or pathologic nystagmus versus other nystagmus-like movements. Pathologic nystagmus may be spontaneous, gaze-evoked, or triggered by provocative maneuvers. The combination of attributes allows differentiation between the many peripheral and central forms.
Is torsional nystagmus central or peripheral?
Nystagmus that is purely horizontal, vertical, or torsional usually has a central cause.
What does Percussiveness mean?
1 : of or relating to percussion especially : operative or operated by striking. 2 : having powerful impact.
Is the nystagmus called a pendular or a jerk?
If the second movement is slow, the nystagmus is said to be pendular. If this second movement is quick, the nystagmus is called jerk nystagmus. By convention, the direction of jerk nystagmus (eg., right-beating nystagmus) is named after the fast phase of nystagmus.
When does a nystagmus become a clinical sign?
Congenital nystagmus with an abrupt onset during the first 3 months of life is usually the presenting clinical sign. The nystagmus often has a pendular waveform that persists but can evolve into a jerk waveform. Nystagmus severity can be invariant in all gaze positions or can vary with horizontal gaze position.
Is there an OKN for horizontal nystagmus?
Horizontal OKN was present in 80% of patients tested, including the three cases with horizontal asymmetric nystagmus. This is atypical in both CIN and SDN, where the OKN is usually absent.
What are the characteristics of a vertical nystagmus?
Vertical pendular nystagmus has characteristics similar to other acquired pendular nystagmus and is often of high frequency and low amplitude. It is associated with a wide range of brainstem and cerebellar disease.