Central vestibular syndromes in roll, pitch, and yaw planes: Topographic diagnosis of brainstem disorders
ABSTRACT Evidence is presented for a clinical classification of central vestibular syndromes according to the three major planes of action of the vestibulo-ocular reflex (VOR): yaw, pitch, and roll. The plane-specific vestibular syndromes are determined by ocular motor, postural, and perceptual signs. Roll plane signs are: torsional nystagmus, skew deviation, ocular torsion, tilts of head, body, and perceived vertical; pitch plane signs are: upbeat/downbeat nystagmus, forward/backward tilts and falls, deviations of perceived horizontal; yaw plane signs are: horizontal nystagmus, past pointing, rotational and lateral body falls, deviation of perceived straight-ahead. The thus defined VOR syndromes allow for a precise topographic diagnosis of brainstem lesions as to their level and side. A tone imbalance in roll indicates unilateral lesions (ipsiversive at pontomedullary level, contraversive at pontomesencephalic level). A tone imbalance in pitch indicates bilateral (paramedian) lesions or bilateral dysfunction of the flocculus. It is hypothesized that signal processing of the VOR in roll and pitch is conveyed by the same rather than separate ascending pathways in the medial longitudinal fasciculus and the brachium conjunctivum. A unilateral lesion (or stimulation) of these ‘graviceptive’ pathways (which transduce input from vertical semicircular canals and otoliths) affects function in roll, whereas bilateral lesions (or stimulation) affects function in pitch. Thus, the vestibular system is able to change its functional plane of action from roll to pitch by switching from a unilateral to a bilateral mode of operation. Therefore a common integrator system is efficient (and sufficient) for both eye movements in roll and pitch (rostral interstitial nucleus of the medial longitudinal fasciculus and rostral interstitial nucleus of Cajal). Clinically this means that bilateral syndromes in roll (skew torsion) manifest in a syndrome in pitch (upbeat- or downbeat nystagmus). Pure syndromes in yaw are rare, since the small causative area covering the medial and superior vestibular nucleus is not only adjacent to but overlapped by the structures also subserving roll and pitch function. A lesion frequently results in mixed (e.g., torsional and horizontal) nystagmus. The lesional sites of yaw syndromes are restricted to the pontomedullary level because of the short distance between the vestibular nuclei and the integration center for horizontal eye movements in the paramedian pontine reticular formation. Syndromes in roll and pitch, however, may arise from brainstem lesions located in an area extending from the medulla to the mesencephalon, an area corresponding to the large distance between the vestibular nuclei and the integration centers for vertical and torsional eye movements in the rostral midbrain.
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ABSTRACT: A group of cells lying along the midline of the mid-medulla, nucleus pararaphales, is shown to play a role in vertical eye movements. Its efferents project along the midline, then pass laterally to follow the ventral external arcuate fibers around the surface of the medulla into the restiform body. The fibers terminate in the flocculus and ventral paraflocculus. This nucleus is one of the "cell groups of the paramedian tracts," which, based on their connectivity, could provide a motor-feedback signal for eye-head position to the cerebellum. Lesions of these pathways could lead to gaze-evoked nystagmus.Annals of the New York Academy of Sciences 07/1996; 781(1):532-40. DOI:10.1111/j.1749-6632.1996.tb15726.x · 4.38 Impact Factor
Article: Binocular vertical diplopia.[Show abstract] [Hide abstract]
ABSTRACT: The assessment of a patient with binocular vertical diplopia begins with a thorough history and neuro-ophthalmologic examination. The neuro-ophthalmologic examination includes observation for a compensatory head, face, or chin position; ocular ductions and versions in the nine cardinal positions of gaze; the three-step test; the double Maddox rod test; indirect ophthalmoscopy to observe the location of the fovea in relationship to the optic nerve head to determine cyclodeviation; and the forced ductions test. Binocular vertical diplopia may be due to supranuclear processes, ocular motor nerve dysfunction, neuromuscular junction disease, diseases of eye muscle, mechanical processes causing vertical eye misalignment, and even retinal disease. In this article, the differential diagnosis of these processes is outlined.Mayo Clinic Proceedings 02/1998; 73(1):55-66. DOI:10.1016/S0025-6196(11)63620-3 · 6.26 Impact Factor
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ABSTRACT: Downbeat and upbeat nystagmus can be classified as central vestibular syndromes in the vertical (pitch) plane of the vestibulo-ocular reflex (VOR) which are defined by ocular motor, perceptual, and postural manifestations. While the ocular motor syndrome was often studied investigations on the perceptual consequences for spatial orientation and motion perception are rare. Subjective visual straight ahead (SVA) and perception of object motion were measured in 11 patients with downbeat (n=6) and upbeat (n=5) nystagmus. Upward deviations of SVA (median +5.2°) were found in downbeat nystagmus, and downward deviations (median −7.8°) in upbeat nystagmus. SVA was deviated toward the slow phase of the vertical nystagmus in the pitch plane and associated with increased fore-aft body sway. Perception of object motion was more severely impaired for vertical (particularly for motion in the direction of slow nystagmus phases) than for horizontal directions in both downbeat and upbeat nystagmus. Impairment of motion perception in the vertical pitch plane of the VOR is beneficial to the extent that it alleviates disturbing oscillopsia due to the involuntary retinal slip. Thus, our findings confirm the hypothesis that downbeat and upbeat nystagmus reflect a central tone imbalance of the VOR in the vertical pitch plane with ocular motor, postural, and perceptual manifestations.Neuroscience Letters 04/1998; 245(1-245):29-32. DOI:10.1016/S0304-3940(98)00175-X · 2.03 Impact Factor