Hypertrophic olivary degeneration (HOD) arises from lesions of the dentato-rubro-olivary pathway (Guillain–Mollaret triangle), and bilateral HOD is the rarest. Our patient, a 42-year-old man with bilateral HOD caused by unilateral midbrain infarction, had both increased dizziness and ataxia as the first symptoms. HOD has no effective treatment and is easily misdiagnosed as other diseases in clinical practice. Our case demonstrated unique HOD symptomatology and emphasizes the important role of magnetic resonance imaging in diagnosing HOD. The use of gabapentin relieved nystagmus in our patient and may provide a reference for the future treatment of such patients.

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a relatively common inherited arterial smooth muscle cell disease. The genetic defect is localized to the notch homolog protein 3 (NOTCH3) gene on chromosome 19q12 and is due to a missense variant in NOTCH3. The main clinical manifestations are transient ischemic attacks and repeated stroke, with cognitive impairments leading to dementia, migraine with aura, and mental/emotional disorders. To date, there is no specific therapeutic option, with only symptomatic supportive treatment for the symptoms of acute stroke, migraine, dementia, and mental abnormalities. Here, we provide a case report of a Chinese patient with CADASIL and a mutation in exon 4 of the NOTCH3 gene (p.Arg133Cys). The patient mainly exhibited recurrent cerebral infarction and affective disorder. Antidepressant treatment combined with repetitive transcranial magnetic stimulation significantly improved the depressive symptoms of the patient.