Paroxysmal tonic upgaze (PTU) of childhood is a rare and distinctive neuro-ophthalmological syndrome characterized by episodes (

paroxysm Paroxysmal attacks or paroxysms are a sudden recurrence or intensification of symptoms, such as a spasm or seizure. These short, frequent symptoms can be observed in various clinical conditions. They are usually associated with multiple scleros ...

s) of sustained upward deviation of the eyes. Symptoms normally appear in babies under one year of age and are characterized by an upward stare or gaze, with the eyes rolled back, while the chin is typically held low.

Presentation

Babies suffering from PTU may exhibit normal or slightly jerky side-to-side eye movement,

nausea Nausea is a diffuse sensation of unease and discomfort, sometimes perceived as an urge to vomit. It can be a debilitating symptom if prolonged and has been described as placing discomfort on the chest, abdomen, or back of the throat. Over 30 d ...

, irritability, frequent sleep, developmental and

language delay Language is a structured system of communication that consists of grammar and vocabulary. It is the primary means by which humans convey meaning, both in spoken and signed forms, and may also be conveyed through writing. Human language is ...

vertigo Vertigo is a condition in which a person has the sensation that they are moving, or that objects around them are moving, when they are not. Often it feels like a spinning or swaying movement. It may be associated with nausea, vomiting, perspira ...

and loss of

muscle tone In physiology, medicine, and anatomy, muscle tone (residual muscle tension or tonus) is the continuous and passive partial contraction of the muscles, or the muscle's resistance to passive stretch during resting state.O’Sullivan, S. B. (2007) ...

. The condition is generally regarded as having a benign outcome, in the sense that it improves, rather than worsens over time. The average age of recovery is at about 2.5 years.

Genetics

This condition has been associated with mutations in the following genes:

CACNA1A Cav2.1, also called the P/ Q voltage-dependent calcium channel, is a calcium channel found mainly in the brain. Specifically, it is found on the presynaptic terminals of neurons in the brain and cerebellum. Cav2.1 plays an important role in contr ...

GRID2 Glutamate receptor, ionotropic, delta 2, also known as GluD2, GluRδ2, or δ2, is a protein that in humans is encoded by the ''GRID2'' gene. This protein together with GluD1 belongs to the delta receptor subtype of ionotropic glutamate receptors ...

and SEPSECS.Quade A, Thiel A, Kurth I, Holtgrewe M, Elbracht M, Beule D, Eggermann K, Scholl UI, Häusler M (2019) Paroxysmal tonic upgaze: A heterogeneous clinical condition responsive to carbonic anhydrase inhibition. Eur J Paediatr Neurol

Treatment

Because of the rarity of this condition there are few reports of successful treatment. Carbonic anhydrase inhibition has been reported to work in a small series. Quade A, Thiel A, Kurth I, Holtgrewe M, Elbracht M, Beule D, Eggermann K, Scholl UI, Häusler M (2019) Paroxysmal tonic upgaze: A heterogeneous clinical condition responsive to carbonic anhydrase inhibition. Eur J Paediatr Neurol

History

PTU was first described in 1988. As of 2002, approximately fifty cases had been diagnosed. Because the condition is so rare, the majority of physicians have never seen it, and thus may not recognize it. Videotaping a child both in and out of the upgaze state can be vital for reaching a diagnosis.

References

{{reflist Neurological disorders in children