Medial Strabismus in Dogs: A Neurological Insight

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Questions and Answers

What neurological sign is highlighted as a localizing indicator in the described cases?

Esotropia (correct)

Ataxia

Hemiplegia

Strabismus

Which imaging technique revealed the ischemic infarction in the dogs?

Ultrasound

Computed Tomography (CT)

Magnetic Resonance Imaging (MRI)

Diffusion-weighted Imaging (DWI) (correct)

What is medial strabismus also known as?

Diplopia

Esotropia (correct)

Exotropia

Hyperopia

What kind of infarction was identified in the dogs presented in the cases?

Lacunar infarction Signup and view all the answers

Which animal was diagnosed with medial strabismus in the case report?

A 7-year-old male neutered Border Collie Signup and view all the answers

What did the computed tomography of the thorax and abdomen reveal?

No significant findings Signup and view all the answers

What neurological condition was associated with the medial strabismus in both dogs?

Vestibular ataxia Signup and view all the answers

What neurological signs were observed in the dog during the examination?

Marked right head tilt and vestibular ataxia Signup and view all the answers

What was suggested by the multiple electrode aggregometry analysis?

Increased platelet activation Signup and view all the answers

What type of brain imaging was used to identify thalamic lesions in the dogs?

Magnetic resonance imaging (MRI) Signup and view all the answers

Which medication was used for antinausea treatment in the dog?

Ondansetron Signup and view all the answers

What condition was the 7-year-old male neutered Border Collie initially evaluated for?

Vestibular ataxia Signup and view all the answers

Which cranial nerve's motor nucleus is affected leading to medial strabismus?

Oculomotor nerve Signup and view all the answers

What does restricted diffusion in imaging typically indicate?

Ischemic changes Signup and view all the answers

What was the outcome for the dog after 7 days of supportive care?

The dog was discharged with resolution of episodic head tremor Signup and view all the answers

What was the main cause of the observed symptoms in the dogs?

Thalamic ischemic infarction Signup and view all the answers

Which artery's territory is associated with the identified ischemic infarct?

Caudal perforating artery Signup and view all the answers

What additional condition was suggested by the neuroanatomical localization in the dog?

Thalamic involvement Signup and view all the answers

What additional symptom was present in both dogs besides medial strabismus?

Nonambulatory tetraparesis Signup and view all the answers

What were the results of the venous blood gas analysis and thyroid profile?

Showed mild hypercholesterolemia Signup and view all the answers

What is a rare consequence of a thalamic ischemic infarction as mentioned in the case report?

Pseudoabducens paralysis Signup and view all the answers

What is pseudoabducens paralysis mainly characterized by?

Increased convergence activity to the eye Signup and view all the answers

Which area is primarily affected by a paramedian thalamic lesion resulting in esotropia?

Oculomotor nerve nucleus Signup and view all the answers

Which condition has NOT been reported to cause esotropia in dogs?

Increased intraocular pressure Signup and view all the answers

What consequence can a thalamic infarct produce regarding strabismus in dogs?

Medial strabismus (esotropia) in the contralateral eye Signup and view all the answers

Which of the following neurological signs is commonly associated with midbrain-thalamic ischemic infarcts in dogs?

Ipsilateral mydriasis Signup and view all the answers

Which of the following describes thalamic esotropia in dogs?

Esotropia secondary to contralateral thalamic infarcts Signup and view all the answers

Which statement regarding pseudoabducens palsy in humans is correct?

It can be either ipsilateral or contralateral to the infarct Signup and view all the answers

What is a key sign that can be manifested due to a dorsal midbrain lesion?

Convergence-retraction nystagmus Signup and view all the answers

Study Notes

Medial Strabismus in Dogs

Rare neurological sign: Medial strabismus (esotropia) at rest is a rare consequence of a contralateral paramedian thalamic ischemic infarction.
Not previously linked to thalamic lesions: While esotropia has been linked to abducens neuropathy or extraocular myopathy in dogs, this report is the first to associate it with thalamic lesions.
Two dogs presented with symptoms: Two dogs (a Border Collie and a mixed breed dog) had peracute non-progressive vestibular ataxia.
Signs in dogs: Neurological examination revealed right esotropia, nonambulatory tetraparesis, head tilt, vestibular ataxia, and nystagmus.
Brain lesions identified: Magnetic resonance imaging (MRI) localized lesions to the left paramedian thalamic lacunar ischemic infarction in both dogs.
Mechanism of esotropia: Interruption of descending inhibitory pathways (crossing in the subthalamic region), that control the contralateral motor nucleus of the oculomotor nerve leads to medial rectus muscle hypertonicity and hence esotropia.
Important diagnostic sign: Esotropia can be a localized sign in dogs with thalamic infarctions.
Treatment: Supportive care, including IV fluids, antiemetic medications, and physiotherapy, were administered to both dogs.
Recovery: Both dogs recovered and were discharged, with the head tremor resolving completely in the first dog nine days later.

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Description

This quiz explores the rare occurrence of medial strabismus (esotropia) in dogs, specifically linked to contralateral paramedian thalamic ischemic infarction. It examines the neurological signs, the case of two affected dogs, and the imaging findings that reveal thalamic lesions. Test your understanding of this intriguing clinical phenomenon in veterinary neurology.