Bidirectionality of the dentato-rubro-thalamo-cortical tract allows concurrent hypoperfusion in ipsilateral cerebellum and contralateral cerebral hemisphere: A case report

RATIONALE: The brain circulation of the dentato-rubro-thalamo-cortical tract (DRTT) has been reported for decade, but is rarely observed using nuclear medicine imaging tools, to analyze a patient with midbrain hemiatrophy syndrome. We present a case that revealed notable interruption in the middle of the DRTT. Finding out whether the superior cerebellar peduncle of the midbrain was injured was a decisive element for developing bidirectional effect of DRTT. PATIENT CONCERNS: A 34-year-old right-handed female presented with progressive weakness and bradykinesia in the left-sided limbs for about 6 months. She had difficulty with hand dexterity for activities of daily life and general tasks. She reported poor balance during walking and sitting. Muscle strength was 3 in the left hand and 4 in the foot due to atrophy of left limbs. The circumference of 10 cm proximally/distally from the lateral epicondyle of the humerus was 25.7/23.8 cm at right and 24.2/20.8 cm at left in the upper limbs, and 15 cm proximally/distally from the lateral joint space was 42.1/35.0 cm at right and 43/30.8 cm at left in the lower limbs. The brain magnetic resonance imaging study revealed a small-sized right midbrain. DIAGNOSIS: Based on the distinct features of limbs atrophy and the locations of the lesions on the magnetic resonance (MR) imaging, the patient was diagnosed with midbrain hemiatrophy syndrome. INTERVENTIONS: The patient was only willing to accept physical and occupational training programs at our outpatient clinic. OUTCOMES: We utilized serial anatomic and functional neuroimaging of the brain to survey the neurologic deficit. Brain perfusion single-photon emission computed tomography (SPECT) showed hypoperfusion over the left fronto-parietal regions, left anterior temporal region, and left occipital region, and also the left striatum and right cerebellum. Symptoms were gradually recovered with rehabilitation, and he was transferred to a rehabilitation facility on hospital day 40. LESSONS: This is the first report to demonstrate concurrent hypoperfusion of ipsilateral cerebellum and contralateral cerebral hemisphere observed on SPECT images in a case of midbrain hemiatrophy syndrome. In our case, with midbrain hemiatrophy syndrome could be explained as mutual direction effect of DRTT.