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Paroxysmal Tonic Gaze Vertical Gaze Phenomena of infancy
see also: Paroxymsal Tonic DownGaze
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Benign Tonic Upgaze vs. Tonic Downgaze in Infants
- Benign (paroxysmal) tonic upgaze and paroxysmal tonic downgaze of infancy are two distinct entities
- Defined by opposite directions of vertical eye deviation and by different clinical courses, associations, and workup implications.
Benign (paroxysmal) tonic upgaze (PTU)
- Characterized by episodes of sustained conjugate upward deviation of the eyes, with compensatory neck flexion (chin-down posture) and incomplete/down-beating saccades on attempted downgaze; horizontal eye movements are normal and consciousness is preserved.
- Onset is typically within the first year (mean age of onset ~5–6 months, though reported from the first week to age 7).
- Features include diurnal fluctuation, relief with sleep, exacerbation by febrile illness/fatigue, and frequently associated ataxia.
- Historically considered benign with eventual resolution, but the label is misleading: substantial proportions have developmental delay, cognitive dysfunction, or abnormal neurological findings, and it is increasingly recognized as part of a neurodevelopmental spectrum with identified genetic bases, especially CACNA1A (also KCNA1, FGF14, GRID2). One acetazolamide-responsive form is CACNA1A-related.
Paroxysmal tonic downgaze of infancy
- Characterized by tonic downward deviation of the eyes (often slightly exotropic), with intermittent upward saccades — the mirror image of PTU. Also described as “benign positional vertical opsoclonus,” often occurring in the supine position.
- An idiopathic/benign form occurs in term infants, presents very early (days to ~12 weeks), and resolves spontaneously (often by ~6 months) with normal development and neuroimaging; a comprehensive workup may be unnecessary in classic benign cases.
- However, symptomatic tonic downgaze is strongly associated with CNS injury — particularly periventricular leukomalacia and hypoxic-ischemic injury in preterm infants, correlating with subcortical visual loss, spastic diplegia/quadriplegia, and developmental delay. It can also be the presenting sign of serious treatable disease (e.g., biotin-thiamine-responsive basal ganglia disease, so context-dependent evaluation is essential.
Key distinctions
| Feature | Benign tonic upgaze (PTU) | Tonic downgaze of infancy |
|---|
| Eye deviation | Sustained upward, with chin-down neck flexion | Sustained downward, often exotropic/supine-triggered |
| Saccade correction | Down-beating saccades on attempted downgaze | Intermittent upward saccades |
| Typical onset | First year, mean ~5–6 mo | Very early (days–12 wk) in benign form |
| Prognosis/associations | Often part of neurodevelopmental spectrum; CACNA1A and other genes | Benign form resolves; symptomatic form linked to PVL/HIE, metabolic disease |
Both are on the differential of nonepileptic paroxysmal eye-movement phenomena of infancy and can be mistaken for seizures, so video documentation and normal EEG during events are useful in distinguishing them from epilepsy. Kartal, Pediatr Emerg Care 2019 Rodan et al., Neurology 2013