Paroxysmal tonic upgaze (PTU) of childhood is a rare and distinctive neuro-ophthalmological syndrome characterized by episodes 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. While not painful, it can be a debilitating symptom if prolonged and has been described as placing discomfort on the chest, abdomen, or back of the ...

, irritability, frequent sleep, developmental and

language delay A language delay is a language disorder in which a child fails to develop language abilities at the usual age-appropriate period in their developmental timetable. It particularly affects deaf children who are denied sign language. It is most commo ...

vertigo Vertigo is a condition where a person has the sensation of movement or of surrounding objects moving when they are not. Often it feels like a spinning or swaying movement. This may be associated with nausea, vomiting, sweating, or difficulties w ...

and loss of

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

. 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 cont ...

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 GRID1, GluD1 belongs to the delta receptor subtype of ionotropic glutamate rec ...

and

SEPSECS O-phosphoseryl-tRNA(Sec) selenium transferase is an enzyme that in humans is encoded by the ''SEPSECS'' gene In biology, the word gene (from , ; "... Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." mea ...

.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