From the Guidelines
Peripheral (oculomotor) nystagmus and central (brainstem or cerebellar) nystagmus have distinct features. The key distinguishing features of peripheral versus central nystagmus are related to their underlying causes and clinical presentations.
Causes and Clinical Presentation
- Peripheral nystagmus is typically caused by vestibular disorders, such as labyrinthitis or vestibular neuronitis, and is often associated with vertigo, dizziness, and nausea 1.
- Central nystagmus, on the other hand, is caused by brainstem or cerebellar lesions, such as stroke, demyelination, or tumors, and may be associated with other neurologic symptoms, such as ataxia, hemiparesis, and sensory loss 1.
Diagnostic Evaluation
- A thorough neuro-ophthalmological examination is essential in evaluating patients with nystagmus, including a complete ophthalmic examination, sensorimotor evaluation, and neurological examination 1.
- Imaging studies, such as MRI, may be necessary to rule out underlying structural lesions, especially in cases of central nystagmus or when there are associated neurologic symptoms 1.
Clinical Features
- Latent nystagmus is a type of nystagmus that is seen under monocular viewing conditions and is characterized by horizontal jerk oscillations of the eyes 1.
- Manifest-latent nystagmus has an identical waveform to latent nystagmus but is evident under binocular viewing conditions and increases with monocular occlusion 1.
- Skew deviation is a vertical strabismus associated with disorders of the vestibular pathways or supranuclear utriculo-ocular pathways, and is characterized by vertical diplopia, ocular torsion, and torticollis 1.
From the Research
Distinguishing Features of Peripheral and Central Nystagmus
The distinguishing features of peripheral (oculomotor) nystagmus versus central (brainstem or cerebellar) nystagmus can be identified through various clinical and pathological characteristics.
- Direction of nystagmus: The direction of nystagmus can be a key differentiator, with peripheral nystagmus typically being unidirectional and central nystagmus being bidirectional or having a more complex pattern 2.
- Associated signs and symptoms: Central nystagmus is often associated with other central ocular motor signs, such as impaired smooth pursuit, gaze-evoked nystagmus, or dysmetric saccades, which can aid in differentiation from peripheral nystagmus 3, 4.
- Response to therapeutic maneuvers: Peripheral nystagmus, such as benign paroxysmal positional vertigo (BPPV), can often be improved with therapeutic liberatory maneuvers, whereas central nystagmus is not typically responsive to these maneuvers 5.
- Anatomical localization: Central nystagmus can be localized to specific brainstem or cerebellar structures, such as the midbrain, pons, medulla, or cerebellum, based on the type of nystagmus and associated signs and symptoms 4.
Clinical Characteristics of Central Nystagmus
Central nystagmus can manifest in various forms, including:
- Downbeat nystagmus: often caused by a bilateral floccular lesion or dysfunction 4
- Upbeat nystagmus: caused by a lesion in the mesencephalon or medulla oblongata 4
- Persistent geotropic positional nystagmus: can be caused by unilateral cerebellar lesions, particularly in the cerebellar tonsil 3
- Perverted head-shaking nystagmus: although not specific for central vestibular pathology, it is more frequently observed in central vestibular disorders 6
Pathophysiological Mechanisms
The pathophysiological mechanisms underlying central nystagmus involve abnormal integration of semicircular canal-related signals by the cerebellar nodulus, uvula, and/or tonsil, leading to an erroneous estimation of head tilt and/or eye position coordinates 5.