Valsalva maneuver suggests increased rigidity of cerebral resistance vessels in familial dysautonomia

Abstract

In familial dysautonomia (FD), cerebral autoregulation (CA) must adjust cerebral blood flow to extreme and rapid fluctuations in systemic blood pressure. Compromised CA during systemic blood pressure (BP) fluctuations might contribute to central autonomic dysfunction in FD. To evaluate CA during rapid BP changes, we monitored heart rate (HR), radial artery BP and middle cerebral artery blood flow velocity (CBFV), using transcranial Doppler sonography, in eight FD patients and twelve age-matched controls in supine position at baseline and during a Valsalva maneuver (VM, 40 mmHg expiratory pressure for 15 seconds). The best of four VM recordings was analyzed. We calculated two autoregulation parameters. CA(II) reflects BP related autoregulatory CBFV increase in late phase II of VM. CA(II) = [(CBFV(II late)-CBFV(II early))/CBFV(II early)]/[(BP(II late)-BP(II early))/BP(II early)]. CA(IV) reflects BP and HR related autoregulatory CBFV increase in phase IV of VM. CA(IV) = (CBFV(IV)/CBFV(I))/(BP(IV)/BP(I))/(HR(IV)/HR(I)). Baseline systemic BP, but not CBFV, was higher in the patients than the controls. During VM, both groups had similar CBFV and BP values, but CAIV and especially CA(II) were significantly lower in the patients than the controls. We have documented that FD patients maintain stable CBFV during rapid BP fluctuations associated with early and late phase II and phase IV of VM suggesting that small intracerebral vessels of FD patients are less responsive to rapid systemic blood pressure fluctuations. To compensate for decreased sympathetic vascular innervation, we propose that FD patients may alter the myogenic component of CA by vessel wall thickening resulting in increased rigidity of intracerebral resistance vessels. The resulting vasoconstriction would allow maintenance of normal baseline CBFV in spite of chronic recumbent hypertension.

Terminal vessel hyperperfusion despite organ hypoperfusion in familial dysautonomia

“…In a study evaluating cerebral blood flow regulation in FD patients during rapid fluctuations in blood pressure, we also obtained findings suggesting increased rigidity of intracerebral resistance vessels [21].…”

“…More importantly, they have to compensate for a chronic and possibly more damaging exposure to arterial hypertension when supine, i.e. during sleep or rest [8,20,21]. Chronic arterial hypertension alters vessel morphology and promotes sclerosis of the vessel walls [22], resulting in increased vessel rigidity and vascular resistance [15,[23][24][25].…”

Autonomic dysfunction affects dynamic cerebral autoregulation during Valsalva maneuver: comparison between healthy and autonomic dysfunction subjects

“…cerebral autoregulation; cerebral vasoreactivity; autonomic nervous system; Valsalva maneuver; transcranial Doppler THE ROLE OF AUTONOMIC NERVOUS system (ANS) in the adaptation of the cerebral vasculature to arterial blood pressure (ABP) fluctuations, commonly referred to as dynamic cerebral autoregulation (CA), has been the subject of ongoing debate (5,15,22,33,50,51,53). Besides considerable physiological interest, it can have profound clinical impact since ANS dysfunction is related to cerebrovascular disease (10) and the cerebrovascular consequences of widely used parasympathatetic and sympathetic modulating drugs are largely ignored.…”

A world without pain or tears*

“…Some of these problems may be due to the intrinsic neurological disorder but it is also possible that abnormal cerebral circulatory responses contribute to the progression [44,46]. This area is extremely problematic and is as yet without treatment.…”