This patient mainly has the manifestation of a subacute decline in cognitive function, while brain CT revealed high-density lesions mainly in the right basal ganglia region. Due to the simultaneous detection of CT high density and T1 high signal in this patient, such manifestations could be easily misdiagnosed as cerebral hemorrhage, calcification, methanol poisoning, and other diseases. Clinicians should be cautious in identifying them. The CT value of intracranial calcified lesions is higher than that of this patient, there is no perifocal edema or space-occupying effect, and the CT value of the lesions does not change over time. Cerebral hemorrhage is not confined solely to the striatum but rather to the vicinity of the lesion, often accompanied by perifocal edema and generally accompanied by hypertension and neurological deficits. Since the patient's high-density lesions and T1 phase high signal lesions on brain CT are confined to the striatum, his blood sugar is poorly controlled, his symptoms and imaging manifestations after blood sugar control recover, and there is no medical history of hypertension, brain edema, or methanol exposure, so we consider this patient as DS. In addition, subacute cognitive decline should also be distinguished from vascular causes, infectious encephalitis, Creutzfeldt Jakob disease, toxic metabolic diseases, and autoimmune encephalitis (including paraneoplasia)[2]. In the imaging examination of the patient, there are no lesions consistent with the distribution of arteries and veins, and there is no evidence of common lobar lesions, poisoning, and infection in encephalitis. Therefore, we do not consider the patient having cerebrovascular diseases, infectious diseases, or immune encephalitis.
DS is a rare disease related to poor blood glucose control. It usually shows unilateral involuntary movement and can occur in patients with T2D and type 1 diabetes(T1D)[1]. It has been reported that the prevalence of DS is less than one in 100000[3]. Ottaviani S et al. collected diabetes patients (HbA1c level more than 8%) who received glycosylated hemoglobin assessment in IRCCS Policlinico San Martino Hospital and had poor blood glucose control from January 2, 2014, to June 1, 2017. He found that the incidence of DS was 0.16%[4]. In the future, with the increasing incidence rate of diabetes, the incidence rate of DS may expand[4]. Acute-onset chorea is the main manifestation of DS[5], related to DS involving the new striatum. The new striatum can release inhibitory neurotransmitters γ- Aminobutyric acid (GABA) to the subthalamic nucleus, inhibiting exercise. When the neostriatum is injured, it can lead to increased excitability in the cortical motor area, manifesting typical involuntary movement[6].
DS patients without involuntary movement are sporadic. Of the 176 DS patients included by Choon Bing Chua et al., only 2.3% of patients showed striatal involvement without the clinical manifestation of chorea[7]. The main manifestations of DS patients who have previously been reported to have no involuntary movements are consciousness disorders, epilepsy, limb weakness, earache, and dysphagia[8-10]. This patient is characterized by decreased cognitive function, which may be rarely reported. We speculate that this patient's cognitive function decline is related to the injury to the right caudate nucleus head. Previous studies have shown that the caudate nucleus receives neuronal inputs from the prefrontal cortex, closely related to cognitive function[11]. When the caudate nucleus is damaged, and the cortex responsible for cognitive function is not damaged or atrophied, the destruction of the limbic system circuit can still lead to fiction, global dementia, speech defects, and neglect syndrome[12]. The CT scan of this patient shows that high density mainly occurs in the right caudate nucleus, and the low signal lesions displayed by SWI are also mainly located in the right caudate nucleus rather than the putamen, indicating that there is relatively severe damage to the caudate nucleus, which is consistent with the symptoms of decreased cognitive function in this patient.
The primary treatment for DS is to control hyperglycemia [16]. However, only a quarter of patients can achieve the goal of correcting DS-related chorea by controlling their blood glucose, and most patients still need additional anti-chorea drugs to control their symptoms [7]. Relevant research shows that [7] the imaging changes of DS abnormalities are reversible, and some patients with CT high-density lesions can recover within ten days after active treatment. Most patients with imaging abnormalities can recover within three months. After seven days of actively controlling blood glucose and other treatments, the CT value of the patient's brain CT lesions began to decline. At the same time, without using drugs such as cholinesterase inhibitors(CHEIs) to improve cognitive function, patients' cognitive function improved, which suggests that DS patients only with the symptom of cognitive decline may improve their cognitive function by positive control of their blood glucose. However, this requires a larger sample of clinical studies to confirm that for DS patients with cognitive decline, if necessary, drugs such as donepezil are still needed to improve cognitive function. Whether patients with DS who only exhibit cognitive decline can improve their symptoms by controlling blood sugar alone will be an exciting research direction in the field of DS treatment in the future.