Brain overheating and rosacea

[Guest guest]

This is the paper I mentioned in previous post. Sentence that stands

out for me is

" Venous blood flow from the skin to the brain appears to be

suppressed in rosacea, thus inhibiting selective brain cooling in

hyperthermic conditions. "

Hence the sns kicks in, because it is convinced your brain is

dangerously close to overheating, and it forces the body to dump heat

in the quickest way possible, i.e. via facial flushing.

Interestingly, the only time I have had absolutely zero flushing was

was couple of years ago when I had a very high fever - my amateur take

on this is that somehow my elevated body temperature seemed to force

my sns to accept (and ignore) any sign of brain over-heating, and

therefore not trigger flushing. Funny thing is that I got off my

death bed to go to my first photoderm consult, and the guy I saw said

he'd never seen anyone as pale come to him looking to get zapped ...

Note the use of ultrasonic doppler to measure facial blood flow (in

1989 ...) - this is the only real way to quantify issues surrounding

facial flushing.

Rick

1: Arch Dermatol Res 1989;281(1):66-72

cea: disturbed defense against brain overheating.

Brinnel H, Friedel J, Caputa M, Cabanac M, Grosshans E.

Service de Medecine, Hopital-Maternite, L'Arbresle, France.

Tympanic (Tty), esophageal (Tes), forehead, and hand skin

temperatures, as well as the forehead

evaporation rate were recorded in six men (four suffering from

rosacea

and two healthy controls)

before, during, and after 1 h of warm bath (38 degrees-39 degrees C).

During the last 30 min of the

bath, the subject's face was vigorously fanned (14 m/s). Blood flow

was explored with ultrasonic

Doppler in the emissary veins of the cranium during normothermia

before entering the bath, and

during hyperthermia just after leaving it. Under normothermic

conditions, Tty was higher than Tes

in all subjects. In three patients, no blood flow could be detected

in

the ophthalmic emissary veins

whereas in the fourth patient as well as in both control subjects,

blood flowed from the intracranium

to the face. During hyperthermia, face fanning decreased Tty by 0.25

degrees +/- 0.05 degrees C

(+/- SEM) below Tes in the control subjects whereas in all patients

Tty remained warmer than Tes

by 0.1 degrees C. Doppler recordings showed a rapid inward blood flow

from the skin to the brain

in the controls during hyperthermia. In patients, however, there was

no change from normothermia

in the blood flow patterns of vena angularis oculi. Their forehead

temperature was permanently

higher than in control subjects. Venous blood flow from the skin to

the brain appears to be

suppressed in rosacea, thus inhibiting selective brain cooling in

hyperthermic conditions. The

importance of this mechanism in the pathogenesis of rosacea and its

significance as a means of

investigation are discussed.

PMID: 2525010 [PubMed - indexed for MEDLINE]