Overview.
Multiple Infarct Dementia (MID) is the most common type of vascular dementia, accounting for 39.4% of cases. As a result of recurrent strokes, cortical, white matter, or basal nucleus regions in the blood supply areas of multiple branches of the middle or posterior cerebral arteries in both hemispheres are involved. It leads to a syndrome of intellectual and cognitive dysfunction and is one of the common causes of Alzheimer’s disease.
Etiology
Cerebrovascular lesions are the direct cause of MID, mainly due to atherosclerosis, arterial stenosis and continuous shedding of atherosclerotic plaques, causing repeated multiple cerebral infarctions, which then lead to MID. risk factors may include age, hypertension, diabetes mellitus, hyperlipidemia, and a history of stroke.
Symptoms
The patient has a history of multiple ischemic stroke events, focal localizing signs of cerebral infarction such as central facial paralysis, hemiparesis, hemiparesis, hemifacial sensory deficits, increased dystonia, cone-bundle sign, pseudo medullary paralysis, hyperalgesia, and urinary and fecal incontinence.
Dementia with multiple cerebral infarcts may start acutely and progress in stages, and the intellectual impairment is often patchy, and the mental activity disorder is directly related to the site and volume of the vascular lesions damaging the brain tissue. Cognitive dysfunction manifests itself in the form of diminished proximal memory and computation, apathy, anxiety, scant speech, depression, getting lost, not recognizing the door of the house, wearing the wrong clothes and pants, and ultimately not being able to take care of oneself.
Compared to Alzheimer’s disease, vascular dementia is less impaired in time and place orientation and repetition, and more impaired in executive functions such as self-organization, planning, and fine-motor synergy work.
Examination
1. Cerebrospinal fluid routine examination
Measurement of APOE polymorphism and quantification of Tau protein and β-amyloid fragment in cerebrospinal fluid and serum.
2. Differential examination
Mainly through the patient’s daily life and social ability assessment and neuropsychological tests, commonly used Simple Mental State Examination Scale (MMSE), Wechsler Adult Intelligence Scale (WAIS-RC), Clinical Dementia Rating Scale (CDR), and Blessed Behavioral Scale (BBBS), etc., and Hachinski Ischemic Score (HIS) can be differentiated from Degenerative Disease Dementia.
3. Neuroimaging
(1) CT scan of the brain can show multiple low-density infarct foci of varying sizes in the cerebral cortex and cerebral white matter, halo-shaped low-density areas next to the lateral ventricles, cerebral leukoaraiosis and cerebral atrophy, and so on.
(2) MRI can show multiple T1WI low signal and T2WI high signal in bilateral basal nuclei, brain cortex and white matter, old foci have clear boundaries and low signals without obvious occupying effect, fresh foci have unclear boundaries and inconspicuous signal intensity, early T1WI changes can be inconspicuous, and T2WI can show the foci; the brain tissues around the foci have limited cerebral atrophy or total cerebral atrophy.
4. Electrophysiologic examination
(1) EEG examination: EEG of normal old people mainly shows slowing down of α rhythm, which slows down from 10~11Hz in young adults to 9.5Hz in old age, with slow waves of 3~8Hz in temporal region; diffuse θ or δ activity in bilateral frontal and central regions, especially in sleepy state, which suggests cerebral aging; α rhythm further slows down to 8~9Hz or less on the basis of the EEG changes caused by the lesions of multiple cerebral infarctions; bilateral θ or δ activity in frontal and central regions, which suggests brain aging; and α rhythm further slows down to 8~9Hz or less on the basis of the EEG changes caused by the lesions of multiple cerebral infarctions. ∼9 Hz or less, and diffuse theta waves with focal paroxysmal high-amplitude δ rhythms appeared in bilateral frontal, temporal, and central regions.
(2) Evoked potentials MEP and SEP both show prolonged latency and decreased wave amplitude, with a positive rate of 80% to 90% or more in large cerebral infarcts and 30% to 50% in small focal infarcts; about 40% of patients with occipital infarcts leading to cortical blindness have abnormal waveforms and prolonged latency time limits on VEP, and VEP waveforms improve markedly after visual restoration; the detection rate of abnormalities on BAEP is 20% to 70% for ischemic strokes; and the detection rate of abnormalities on BAEP is 20% to 70% for ischemic stroke. The detection rate of BAEP in ischemic stroke is 20% to 70%, which is characterized by delayed inter-peak latency (IPL) of I-V. In patients with brainstem infarction, BAEP is abnormal bilaterally, with disappearance of IV-V waveforms and prolongation of absolute latency (PL).
Diagnosis
Based on recurrent stroke events, accompanying neurolocalization signs and cognitive dysfunction, the definitive diagnosis relies on pathological examination.
Dementia occurs suddenly or slowly with cerebrovascular events and manifests as cognitive dysfunction and mood changes such as depression. The disease progresses in stages, with signs of cortical and subcortical dysfunction such as aphasia, hemiparesis, sensory deficits, hemianopsia, and pyramidal signs, and focal neurologic deficits.Multiple infarcts are seen on CT or MRI.
Treatment
1. Treatment of hypertension
Maintaining blood pressure at an appropriate level can prevent and delay the onset of dementia. Some scholars found that in patients with vascular dementia (VD) and hypertension, systolic blood pressure control at 135-150mmHg can improve cognitive function, and symptoms deteriorate below this level. Improve cerebral circulation, increase cerebral blood flow, improve oxygen utilization.
2.Brain metabolizer
Promote the utilization of amino acids, phospholipids and glucose by brain cells, enhance the patient’s responsiveness and excitability, and enhance memory.
3.Rehabilitation therapy
Since vascular dementia is often characterized by patchy or non-comprehensive damage to intelligence, accompanied by focal neurological signs, rehabilitation therapy can often achieve better results. Rehabilitation should be targeted, including daily life ability training, muscle and joint mobility training and speech disorder rehabilitation. Patients should be allowed to have more contact with the outside world and participate in certain social activities. The quality of life of patients can be improved through comprehensive treatment with Chinese and western medicines, rehabilitation and nursing care.
Prognosis
The prognosis of dementia is closely related to that of cerebrovascular disease, while the prognosis of dementia is inconsistent depending on the site and scope of the lesion, but the process of cognitive function decline is irreversible.
Early detection and avoidance of stroke risk factors such as hypertension, diabetes mellitus and hyperlipidemia and active treatment, and surgical treatment for high carotid stenosis. It helps to reduce the occurrence of vascular dementia. Smoking cessation, alcohol control and reasonable diet. Those with clear genetic background should undergo genetic diagnosis and treatment.