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tonic_downgaze_children [2026/09/20 10:32] – created Scott Larsontonic_downgaze_children [2026/09/20 10:34] (current) – [Causes] Scott Larson
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-====== Tonic Downgaze in infants ======+====== Paroxysmal Tonic Downgaze in infants ======
  
 Paroxysmal tonic downgaze (PTD) of infancy is a supranuclear gaze disorder marked by intermittent, conjugate downward deviation of the eyes. It occurs in a **benign idiopathic** form and a **symptomatic** form associated with CNS injury. Paroxysmal tonic downgaze (PTD) of infancy is a supranuclear gaze disorder marked by intermittent, conjugate downward deviation of the eyes. It occurs in a **benign idiopathic** form and a **symptomatic** form associated with CNS injury.
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   * **Benign (idiopathic) PTD** — Otherwise healthy term infants; transient, typically resolves by ~6 months; normal neuroimaging and no sequelae. Proposed mechanism: immaturity/delayed myelination of cortico-mesencephalic vertical gaze pathways.   * **Benign (idiopathic) PTD** — Otherwise healthy term infants; transient, typically resolves by ~6 months; normal neuroimaging and no sequelae. Proposed mechanism: immaturity/delayed myelination of cortico-mesencephalic vertical gaze pathways.
   * **Transient tonic downgaze in preterm infants** — Extremely preterm infants (22–28 weeks), onset at 36–38 weeks postmenstrual age; episodes often provoked by stimuli or feeding.   * **Transient tonic downgaze in preterm infants** — Extremely preterm infants (22–28 weeks), onset at 36–38 weeks postmenstrual age; episodes often provoked by stimuli or feeding.
-  * **Symptomatic tonic downgaze from CNS injury** — Associated with hypoxic-ischemic injury/periventricular leukomalacia; preterm infants with spastic diplegia/quadriplegia, developmental delay, visual impairment. Suggests subcortical visual loss (optic radiations/thalamus).+  * **Tonic downgaze from CNS injury** — Associated with hypoxic-ischemic injury/periventricular leukomalacia; preterm infants with spastic diplegia/quadriplegia, developmental delay, visual impairment. Suggests subcortical visual loss (optic radiations/thalamus).
   * **Other structural causes to exclude** — Raised intracranial pressure/hydrocephalus, posterior fossa or dorsal midbrain (tectal) pathology (overlap with "setting-sun sign").   * **Other structural causes to exclude** — Raised intracranial pressure/hydrocephalus, posterior fossa or dorsal midbrain (tectal) pathology (overlap with "setting-sun sign").