_Vertigo_, or _giddiness_, though unattended with pain, is, in general,
of a more dangerous nature than the severest headach. Vertigo consists
in a disturbance of the _voluntary power_, and in some degree of
_sensation_, especially of _vision_; and thus it shows itself to be an
affection of the brain itself; while mere pain in the head does not
necessarily imply this, it being for the most part an affection of the
membranes only. In _vertigo_, objects that are fixed appear to be in
motion, or to turn round, as the name implies. The patient loses his
balance, and is inclined to fall down. It often is followed immediately
by severe headach. _Vertigo_ is apt to recur, and thus often becomes
frequent and habitual. After a time the mental powers become impaired,
and complete idiocy often follows; as was the case in the celebrated
Dean Swift. It frequently terminates in apoplexy or palsy, from the
extension of disease in the brain.
_Causes.--Vertigo_ is induced by whatever is capable of disturbing
suddenly the circulation of the brain, whether in the way of increase or
diminution: thus the approach of _syncope_, whether produced by loss of
blood, or a feeling of nausea; blows on the head, occasioning a
concussion of the brain; stooping; swinging; whirling; or other unusual
motions of the body, as in sailing, are the ordinary exciting causes of
the disease. _Vertigo_ is exceedingly frequent at an advanced period of
life, and generally indicates the approach and formation of disease in
the brain. Accordingly, it is a frequent forerunner of _apoplexy_ and
_palsy_.
The immediate or _proximate_ cause of _giddiness_, or _vertigo_, that
is, the actual condition of the brain at the moment, is probably some
partial disturbance in the circulation there; which all the _occasional
causes_ mentioned are obviously calculated to produce. It is more or
less dangerous, according to the cause inducing it, and the state of the
brain itself, which may be sound or otherwise. And as this cannot be
certainly known, nor the extent of it when actually present, the event
is of course uncertain. At all times, your _prognosis_ should be
guarded; because _vertigo_ seldom occurs under favourable circumstances
of age and general health; unless when produced by so slight a cause as
_bloodletting_, or a trifling blow upon the head. Whenever _vertigo_
recurs frequently, and at an advanced period of life; and more
particularly when it is accompanied with drowsiness; weakness of the
voluntary muscles; impaired memory, or judgment; or, in short, any other
disturbance or imperfection in the state of the _sensorial_ functions;
an unfavourable result is to be expected; because all these afford
decisive evidence of a considerable degree and extent of disease in the
brain--_Dr. Clutterbuck's Lectures on the Nervous System_.