A 65-year-old Japanese woman developed difficulty in outputting words when she was 60 years old. Motor aphasic symptoms gradually progressed. The patient showed difficulty in understanding conversations at the age of 64 years. She visited a clinic where haloperidol and biperiden were administered. Around the same time, she developed gait disturbance. Three months after starting her course of treatment, she experienced a fall that resulted in brain trauma. The following day, the patient experienced a repeated fall. Two days after the second fall, the patient was admitted to a hospital for gait disturbance and repeated falls. On neurological examination, her Glasgow Coma Scale (GCS) score was E4VAM6. She showed signs of parkinsonism such as akinesia, axial and left-side predominant limb rigidity, and postural disturbance. Brain computed tomography revealed mild intraventricular hemorrhage with subdural hygroma (shown in Fig. 1a). The susceptibility-weighted image of brain magnetic resonance imaging detected mild SAH with intraventricular hemorrhage (shown in Fig. 1b, c). Ventricular size was normal (shown in Fig. 1d). No aneurysm was detected on magnetic resonance angiography. These findings of brain imaging suggested that her brain trauma was mild. However, gait disturbance and hyporesponsiveness gradually exacerbated despite the discontinuation of antipsychotic drugs and initiation of rehabilitation. One month later, she was transferred to our hospital.

On admission, a physical examination revealed no abnormal findings. On neurological examination, the patient showed severe motor aphasia, and her GCS score was E4VAM5. She was unable to sufficiently comply with verbal instructions. The patient showed mild limitation of vertical eye movement. Paralysis was not apparent. Parkinsonism, such as limb and trunk muscle stiffness and akinesia, was detected. Pyramidal signs such as hyperreflexia and pathological reflexes with a positive grasp reflex were apparent. She was unable to stand and walk. Blood test results revealed no abnormalities, including blood count, electrolytes, glucose levels, and thyroid function. Tests for whole-blood tuberculosis-specific interferon-gamma assay and serum cryptococcal antigen were negative. The appearance of cerebrospinal fluid (CSF) was clear, with an opening pressure of 135 mm H₂O. Mildly elevated levels of CSF protein (54 mg/dL) and cell count (10 cells/μL with 100% mononuclear cells) were detected along with normal glucose levels (69 mg/dL). Cultures of bacteria, fungi, and acid-fast bacilli in the CSF were negative. Additionally, CSF cytology was classified as class I. Electroencephalogram showed diffuse slow waves without paroxysmal activity. Brain magnetic resonance imaging revealed prominent communicating hydrocephalus (shown in Fig. 1e). Conservative treatment with oral L-DOPA at a maximum dose of 450 mg/day did not improve the patient's neurological condition. A ventriculoperitoneal (VP) shunt was performed on day 23 after admission to our hospital. To make a histopathological diagnosis of underlying diseases causing aphasia and parkinsonism, brain biopsy from the right parietal lobe at a site inserting a VP shunt tube was performed after obtaining an informed consent from her family. The size of the ventricle was reduced following the operation (shown in Fig. 1f). However, the patient's neurological condition did not change remarkably. Brain pathology showed ballooned neurons on hematoxylin-eosin staining (shown in Fig. 2a). Neuropil threads (shown in Fig. 2b) and coiled bodies (shown in Fig. 2c) were detected by Gallyas staining. Phosphorylated-tau immunostaining showed positivity for the neuropil threads and coiled bodies, as well as in the cytoplasm of some neurons (shown in Fig. 2d). No astrocytic plaques were detected in the biopsy specimens. These pathological findings confirmed the diagnosis of CBD as an underlying disease presenting with aphasia and parkinsonism. She was transferred to another hospital and moved to a long-term care facility. Six months after the VP shunt placement, her neurological condition did not improve.