Stroke is the second major cause of death across the world leading to high mortality
rates and leaving those who experience stroke with a poor quality of life. Lacunar stroke
accounts for a quarter of ischemic stroke events and can occur at any age, but is more
frequent in the older generation (>65 years) yet not uncommon in younger patients.
Lacunar stroke is caused by small vessel disease, whereby occlusions or thrombi occur in
the small vessels found deep in the brain structures, around the circle of Willis. This
event leads to a decrease in blood supply to certain areas of the brain and damage to
surrounding tissues, leaving the brain in a vulnerable state. Further events are then
likely to occur such as recurrent stroke, intracranial haemorrhage, additional ischemic
events, prolonging symptoms and increasing the risk of damage to the brain. Even though
lacunar infarcts occur only in the small vessels of the brain, cognitive impairment is
commonly seen post-lacunar stroke emphasising the importance of understanding the
trajectory of cerebral haemodynamics after a lacunar infarction. Common treatments
involve the use of anticoagulants, antiplatelet therapies (both to stop further blood
clots forming), blood pressure (BP) lowering agents (reducing BP to reduce fluctuations
in cerebral blood flow) and the management of hyperglycaemia (to help reduce damage to
blood vessels).
Cerebral autoregulation (CA) plays a large part in regulating cerebral blood flow (CBF),
through maintaining cerebral perfusion, even with fluctuating BP. It does this by
regulating the cerebral vasculature through adjustments in vessel diameter. CA has been
assessed at rest and challenged with paradigms in healthy volunteers and lacunar stroke
patients, however comparisons between younger and older lacunar events incorporating risk
factors has not been looked at. The difference in CA phenotype between those with
uncontrolled high-risk cardiometabolic factors (often younger patients) and those with
moderate/severe small vessel disease and recurrent lacunar stroke syndromes (often older
patients) is unknown. Therefore, exploring different risk factors and the different
lacunar disease phenotypes is important to identify any differences in cerebral
haemodynamics.
Assessing dynamic CA (dCA) in response to fluctuations in BP represents how CA responds
to BP fluctuations in the body, allowing better application to the human vasculature,
compared to assessing static CA. Multiple paradigms and manoeuvres have been used to
assess dCA by inducing a rapid change in BP, but both patient tolerability and ability to
measure dCA accurately need to be considered for this study. The sit-stand manoeuvre is a
clinically applicable manoeuvre which can be done both in the ward and laboratory with
minimal stress to the patient. This manoeuvre has been evaluated in a published review
and compared to a thigh-cuff technique which has been used extensively in previous
research. The thigh-cuff technique induces a rapid change in arterial blood pressure
(ABP) through the rapid deflation of the thigh cuff. However, this repeated action can be
painful for some participants making it difficult to apply clinically to frail patients
leading to issues of unsuccessful repeats. The review found that autoregulatory index
(ARI) values were similar across both the sit-stand and thigh-cuff manoeuvres, showing
sit-stand is an accurate manoeuvre to measure CA. The sit-stand manoeuvre was also better
tolerated compared to the thigh-cuff.
Following up patients post-stroke as high-risk factors are controlled will help
understand changes in CA and could help guide the timing of interventions to manipulate
BP and potentially for the impact of rehabilitation programmes.
Lacunar stroke is one of the most common types of stroke, occurring in both younger and
older generations. Some studies have observed impaired brain blood flow regulation
(cerebral autoregulation) in a cohort of ~57 years of age (median), which has also been
seen in those with small vessel disease. Small vessel disease is often seen in older
patients who often present with recurrent lacunar strokes despite earlier management of
risk factors.
By targeting a younger cohort with uncontrolled risk factors (hypertension and diabetes),
the investigators aim to perform a more comprehensive study to investigate the
haemodynamic consequences of lacunar strokes in this group. This would be done by using
Transcranial Doppler ultrasound (TDC) to measure CBv in patients who are diagnosed with a
lacunar stroke and have undiagnosed diabetes and/or hypertension at their initial
appointment. To measure a dCA response, the sit-stand manoeuvre will be used. These
patients would then receive management of their risk-factors and would be asked to
undergo another TCD assessment 4 weeks after their initial appointment. Data would be
collected and analysed to look at any differences in cerebral haemodynamics between
before and after management of such risk factors.