2020 年 113 巻 1 号 p. 19-24
Wernicke encephalopathy is a clinically-diagnosed disease characterized by disturbed consciousness, disordered eye movements, and ataxia. Given its high specificity for detecting Wernicke encephalopathy, brain MRI has an important role in the diagnosis of this disease. On the other hand, the sensitivity of MRI is relatively low. Therefore, normal brain MRI findings often do not show non-Wernicke encephalopathy.
A 76-year-old man presented to our hospital with a ten-day history of dizziness. Five days earlier, he underwent brain MRI at another hospital. The scans appeared normal, and he was referred to an ear, nose, and throat hospital in order to rule out potential inner ear involvement.
He did not exhibit quadriplegia, spontaneous nystagmus, or positional nystagmus but appeared unsteady when standing during our medical examination. Additionally, his eyes showed leftward and downward gaze-evoked nystagmus, slight rightward and upward gaze-nystagmus, and conjugate gaze palsy toward the right side. We suspected a central nervous system disorder because of the disordered eye movements and carried out a second brain MRI at our hospital. Although the results did not show any cerebral infarction or cerebral hemorrhage, fluid-attenuated inversion recovery (FLAIR) imaging showed an area of slight high intensity in the medial thalami and periaqueductal region. Such findings are characteristic of Wernicke encephalopathy. We administered intravenous doses of vitamin B1 to the patient for one week, during which time his dizziness improved day by day. The disordered eye movements also improved and were resolved completely nine days after beginning the vitamin treatment. A repeat brain MRI was completed the same day, and the high-intensity areas that were noted previously were not visualized on FLAIR. He started rehabilitation three days after beginning treatment and left the hospital 24 days later.
In patients with Wernicke encephalopathy, brain MRI scans may appear normal. If Wernicke encephalopathy is diagnosed clinically based on physical examination findings, then vitamin B1 should be promptly administered.