One-and-a-half syndrome--two cases.

Area of Science:

• Neurology
• Neuroscience
• Ophthalmology

Background:

• One-and-a-half syndrome presents with unilateral horizontal gaze palsy and internuclear ophthalmoplegia, often causing double vision and oscillopsia.
• Lesions typically affect the paramedian pontine reticular formation, impacting horizontal gaze centers and the medial longitudinal fasciculus.
• Common etiologies include vascular insults, multiple sclerosis, and brainstem tumors.

Observation:

• Two cases of one-and-a-half syndrome are presented, both linked to lacunar infarction in the paramedian pontine tegmentum, confirmed by MRI.
• The first patient exhibited an isolated eye movement disorder, while the second presented with additional nuclear-type facial paresis.
• Brainstem evoked potentials indicated brainstem damage in the first patient but were normal in the second.

Findings:

• Lacunar infarction in the paramedian pontine tegmentum is identified as a cause of one-and-a-half syndrome.
• The clinical presentation can vary, with or without additional neurological signs like facial paresis.
• Brainstem evoked potentials may help in assessing the extent of brainstem damage.

Implications:

• This study underscores the importance of neuroimaging, particularly MRI, in diagnosing the underlying causes of one-and-a-half syndrome.
• Early identification and management of vascular risk factors are crucial for patients with stroke-related one-and-a-half syndrome.
• The rapid improvement of ocular symptoms suggests potential for neuroplasticity and recovery in certain cases.