Reduced perfusion in the anterior cingulate cortex of patients with pure autonomic failure: an 123I-IMP SPECT study

Cerebellar impairment during an orthostatic challenge in patients with neurogenic orthostatic hypotension

OBJECTIVE

Compare activation patterns within the cortical autonomic network in patients with neurogenic orthostatic hypotension (NOH) versus healthy age-matched controls during an orthostatic challenge.

METHODS

Fifteen health controls and 15 NOH patients performed 3 Valsalva maneuvers, and 5-min of lower-body negative pressure (LBNP) during a functional brain MRI.

RESULTS

Compared to controls, NOH patients had significantly less activation within the cerebellum during both LBNP and VM. Both groups had significant activation of the bilateral insula and left thalamus during LBNP. No significant differences were found during the recovery phase of LBNP.

CONCLUSIONS

The cerebellum, which plays an important role in vestibulo-sympathetic reflexes, important for blood pressure adjustments during postural changes, appear to be affected in patients with NOH. The cerebellum also appears to be affected during other baroreflex mediated stressors such as the VM.

SIGNIFICANCE

Orthostatic reflexes mediated by the cerebellum may be impaired in patients with NOH. The results suggest an additional pathological pathway in patients with autonomic failure.

[Cardiovascular autonomic function and brain imaging]

The cardiovascular system is regulated by cortical modulation such as the anterior cingulate gyrus, insular cortex, amygdala as well as the reticular formation of the brainstem, including ventrolateral medulla (vasopressor center). These structures are called as the central autonomic network (CAN), and its dysfunction causes autonomic dysregulation. For example, ventrolateral medulla compression by tortuous or ectatic vessels has been etiologically linked with essential hypertension. In regard to a relationship of the cerebral cortex and autonomic dysfunction, hypoperfusion of the anterior cingulate gyrus may be seen in patients with chronic autonomic failure such as pure autonomic failure. Meanwhile, patients with chronic hypertension may also show hypoperfusion of the anterior cingulate gyrus. These findings indicate that inadequate internal environment such as hypotension and hypertension in long term can reduce activities of the anterior cingulate gyrus. In regard to the insular cortex, a relationship with cardiac events or sudden death has drawn attention but now it may be time to revaluate this relationship. Amygdala also play an important role in autonomic regulation. Patients with bilateral amygdala damage show s poor autonomic response to mental stress which induces emotional change.

[Cognitive function and blood pressure regulation in Lewy body diseases]

It is well known that autonomic failure is severer in patients with dementia with Lewy bodies (DLB) compared with patients with Parkinson's disease (PD). According to the Braak's hypothesis, Lewy bodies first appear in the olfactory bulb or peripheral autonomic nervous system. Lewy bodies in the peripheral autonomic nervous system ascend to dorsal motor nuclei of vagus nerve, while those in the olfactory bulb expand to the limbic system. Lewy bodies later attain the substantia nigra. However, it seems that Braak staging can not explain difference in severity of autonomic failure between DLB and PD. As a possibility, in DLB patients with significant autonomic failure, Lewy bodies may have been localized to the peripheral autonomic nervous system in a long time before onset of dementia or parkinsonism, and propagation of Lewy bodies into the central nervous system may be initiated by apparition of certain promotion factor, such as ageing and amyloid-β.

Early and presenting symptoms of dementia with lewy bodies

BACKGROUND/AIMS

To explore the presenting and early symptoms of dementia with Lewy bodies (DLB).

METHOD

Patients with mild dementia fulfilling diagnostic criteria for DLB (n = 61) and Alzheimer's disease (AD) (n = 109) were recruited from outpatient dementia clinics in western Norway. At diagnosis, caregivers were asked which symptom had been the presenting symptom of dementia.

RESULTS

Caregivers reported that memory impairment was the most common presenting symptom in DLB (57%), followed by visual hallucinations (44%), depression (34%), problem solving difficulties (33%), gait problems (28%), and tremor/stiffness (25%). In contrast, 99% of AD carers reported impaired memory as a presenting symptom, whereas visual hallucinations were a presenting symptom in 3% of the AD cases.

CONCLUSION

DLB should be suspected in predementia cases with visual hallucinations.