Magnetic resonance imaging (MRI) has revealed age-related changes in midbrain volume in normal subjects. Atrophy of the midbrain in patients with progressive supranuclear palsy (PSP) has been demonstrated using conventional brain MRI, and it was recently reported that some patients with vascular dementia also have midbrain atrophy. The aim of the present study was to investigate if the patients with subcortical ischemic vascular dementia (SIVD) have atrophic changes in the midbrain. MRIs of 23 SIVD patients, 18 probable PSP patients, and 96 controls were retrospectively analyzed. Differences in the distances between midbrain structures were compared across the patient groups and controls. We measured the anteroposterior diameter (AP), and the distance between the interpeduncular fossa and the aqueduct (IF–AQ), the aqueduct and posterior margin of the superior colliculi (AQ–SC), and the peduncular prominence and the interpeduncular fossa (PP–IF) of the midbrain. The AP diameter and IF–AQ were negatively correlated with age in normal controls (r = -0.21, p < 0.005 for AP; r = -0.14, p < 0.0001 for IF–AQ). In SIVD patients, the AP diameter and IF–AQ were both significantly smaller than in controls (p < 0.001). Changes in the midbrain found for SIVD patients were similar to those seen in PSP patients. Our results suggest that the midbrain decreases in size with normal aging, especially around the tegmental region. This change is more pronounced in patients with SIVD and in patients with PSP. Prospective functional studies are needed to ascertain the clinical relevance of midbrain atrophy in SIVD.

Clonus is the rhythmic muscle contraction which usually occurs in patients with lesions involving descending motor pathways. Sometimes, rhythmic oscillation of action induced clonus could be confused to action tremor. We report a case of action induced clonus associated with cervical schwannoma which was misdiagnosed as essential tremor. The patient had spasticity in all limbs with exaggerated tendon reflexes, and passive stretch-induced clonus. Imaging and histological examinations revealed a schwannoma extending from C2 to C7. The lesion was partially removed by surgery. Even though essential tremor is a common disease, clinician have to do sufficient neurologic examination considering differential diagnosis.

Hemichorea-hemiballism (HC-HB) is a complication of non-ketotic hyperglycemia (NKH); in NKH patients, the frequency of occurrence of HC-HB is greater than that of bilateral chorea. We report the case of a hyperglycemic patient who showed chorea in both the lower limbs. Magnetic resonance imaging (MRI) of the brain revealed high signal intensity on T1-weighted images of the bilateral dorsolateral putamen. The abnormal involuntary movements disappeared after oral administration of haloperidol. Our case report that chorea associated with NKH is correlated with the topography of the basal ganglia.

Pantothenate kinase-associated neurodegeneration (PKAN) is an autosomal recessive disorder that is characterized by mutations in the pantothenate kinase 2 gene (PANK2) and typical magnetic resonance imaging findings. We report a case of atypical PKAN presenting with generalized dystonia. Our patient had compound heterozygous mutations in the PANK2 gene, including mutation in exon 3 (p.D268G) and exon 4 (p.R330P). To our knowledge, this patient is the first to have the p.R330P mutation and the second to have the p.D268G mutation.