Oculomotor Apraxia

Clinical Characteristics
Ocular Features: 

This is a disorder of impaired smooth ocular pursuit movements.  Voluntary horizontal eye movements are absent or defective while vertical gaze and random eye movements are usually retained.  Patients learn early to compensate by sharply turning the head in a jerky, thrusting fashion.  The head turn often overshoots because the eyes tend to deviate in the opposite direction as a result of the vestibular reflex.  Blinking is also sometimes employed to initiate eye movements.  The condition is likely congenital in onset but it is not progressive.  In fact, the ability to look from side to side improves in at least some patients.

Systemic Features: 

The small number of reported patients has limited description of the full phenotype but this seems to be a generalized neurological disorder.  Patients have been reported with global developmental delay, hypotonia, cognitive delays, ataxia/clumsiness, and speech difficulties.  Neuroimaging may reveal abnormalities in various brain stuctures including the cerebellum, cerebrum, vermis, and corpus callosum in 40% of patients.       

Genetics

The genetics of isolated oculomotor apraxia is unknown since no responsible mutation has been identified.  However, familial cases are known, including twins and sibling offspring of consanguineous matings, as well as multigenerational cases.  This condition may be genetically heterogeneous since autosomal recessive and autosomal dominant transmission patterns seem equally likely.  It may also be possible that the Cogan-type oculomotor apraxia is not a isolated entity but simply an associated sign as part of more generalized neurological disease.

Oculomotor apraxia may also be seen in ataxia-telangiectasia (208900), ataxia with oculomotor apraxia 1 (208920), ataxia with oculomotor apraxia 2 (602600) and in Gaucher disease (203800).  It may be the presenting sign in the latter disease.  

Treatment
Treatment Options: 

No treatment is known.

References
Article Title: 

Nosological delineation of congenital ocular motor apraxia type Cogan: an observational study

Wente S, Schroder S, Buckard J, Buttel HM, von Deimling F, Diener W, Haussler M, Hubschle S, Kinder S, Kurlemann G, Kretzschmar C, Lingen M, Maroske W, Mundt D, Sanchez-Albisua I, Seeger J, Toelle SP, Boltshauser E, Brockmann K. Nosological delineation of congenital ocular motor apraxia type Cogan: an observational study. Orphanet J Rare Dis. 2016 Jul 29;11(1):104. doi: 10.1186/s13023-016-0486-z.

PubMed ID: 
27473762

References

Wente S, Schroder S, Buckard J, Buttel HM, von Deimling F, Diener W, Haussler M, Hubschle S, Kinder S, Kurlemann G, Kretzschmar C, Lingen M, Maroske W, Mundt D, Sanchez-Albisua I, Seeger J, Toelle SP, Boltshauser E, Brockmann K. Nosological delineation of congenital ocular motor apraxia type Cogan: an observational study. Orphanet J Rare Dis. 2016 Jul 29;11(1):104. doi: 10.1186/s13023-016-0486-z.

PubMedID: 27473762

Salman MS, Ikeda KM. The syndrome of infantile-onset saccade initiation delay. Can J Neurol Sci. 2013 Mar;40(2):235-40.

PubMedID: 23419574

Harris CM, Hodgkins PR, Kriss A, Chong WK, Thompson DA, Mezey LE, Shawkat FS, Taylor DS, Wilson J. Familial congenital saccade initiation failure and isolated cerebellar vermis hypoplasia. Dev Med Child Neurol. 1998 Nov;40(11):775-9.

PubMedID: 9881808

Zee DS, Yee RD, Singer HS. Congenital ocular motor apraxia. Brain. 1977 Sep;100(3):581-99.

PubMedID: 589433

Cogan DG. Heredity of congenital ocular motor apraxia. Trans Am Acad Ophthalmol Otolaryngol. 1972 Jan-Feb;76(1):60-3.

PubMedID: 5024601