[Background] Supranuclear extraorbital muscle palsy is the core feature of progressive supranuclear palsy (PSP), and ordinarily presents as spontaneous vertical gaze constriction. However, higher visual function associated with visuospatial cognition in PSP patients was not previously considered. [Case presentation] We present a 72-year old right-handed man with PSP- Richardson syndrome (PSP-RS) and abnormal higher visual function. His symptoms began 2 years previously and included the use of small steps while walking, forgetfulness, and postural instability. Neurological examination revealed supranuclear vertical gaze limitation, akinesia, and lead-pipe rigidity without laterality. Neuro-ophthalmological examination showed abnormal ocular movement consistent with PSP, and no visual abnormality was observed. General cognitive functions, including attention and prominent visuospatial orientation and visual attention disturbances, were assessed using neuropsychological tests and concomitant spatial agraphia and impaired configuration using figure copying. Although he presented with mildly decreased and monotonous speech with palilalia, he showed no apparent aphasia, apraxia, visual object agnosia, or Bálint's 'optische Ataxie' i.e. visual ataxia under fixation. Brain MRI revealed atrophy of the mesencephalic tegmentum, bilateral frontal lobe, and bilateral hippocampus. N-isopropyl-p-(iodine-123)-iodoamphetamine single photon emission computed tomography revealed decreased cerebral blood flow in the bilateral frontal lobe, lateral temporal lobe, and basal ganglia. Dopamine transporter single photon emission CT revealed uptake attenuation in the bilateral striatum. 123I-metaiodobenzyl-guanidine myocardium scintigraphy results were normal. [Discussion] The patient's symptoms indicated classical PSP-RS accompanied with a combination of disturbances in spatial orientation and visual attention as noted by Holmes and Horrax and 'ataxie optique' by Garcin. Thus, as observed in this patient, many clinically diagnosed PSP patients with undiagnosed higher visual dysfunction, masked by limited eye movement may exist. These symptoms may further our understanding about posterior cortical atrophy and tauopathy including not only PSP but also corticobasal syndrome and Alzheimer disease.
Keywords: Bálint syndrome; ataxie optique; disturbance of visual attention; posterior cortical atrophy; progressive supranuclear palsy.