NERVOUS SYMPTOMS. 62c
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quence of which the patient feels a pain, {traitnefs, fulnefs, and pul-
fation about the fore-head and temples.
2. A vifcid or acrid humour obftrudling or irritating the final!
veflels of the pericranium, mufcles of the head, or dura mater, and
confequently affecting the nerves of thofe parts with a painful fen-
fation. This may be often no other than a rheumatic, gouty, or
fcorbutic humour falling chiefly on the head.
3. A particular weaknefs, delicacy, and fenfibility of the nerves
of thofe parts of the head ^ whence, from fudden changes of wea¬
ther, errors in diet, fatigue of body, ftrong pallions, intenfe appli¬
cation of mind, fuppreflion of ordinary evacuations, or even from
{lighter caufes,thefe nerves being eafily fufceptible of pain, the fmalL
veflels to which they are diftributed become aflecfted either with
violent alternate contractions and relaxations, or with a fixed fpafm..
This feems to be confirmed by obferving, that women liable to thefe
periodic headachs fufler moft feverely about the menftrual periods y
at which time it is well known, that iflues and other fores become
generally more painful and inflamed, as being more irritable and
eafily affe&ed than the other parts-. In any general indifpofitionr
thofe parts which are le aft firm and found fufler moft..
How thefe headachs fhould return every day, or fometimes once
in two days, is a hard queftion.. We know, that intermitting fe¬
vers obferve very regular periods :: And I have feen epileptic patients
have fits once or twice every day, or once in two days, almoft pre-
cifely at the fame hour. Hyfieric convulfions and other difeafes
have alfo been obferved fometimes to be regularly periodical.
Does the morbid matter in fuch cafes, after being diflodged by
the violence of the paroxyfm, require a certain time before it is
again collected or depofited on the parts affected in fuch a. quanr
tity as is fufficient to produce a new fit? Such is the obfcurity of
Nature in many of her operations, that we meet almoft every where
with appearances of which we are unable to give any fatisfaélory
explanation. However, both in natural philofophy^ and: medi¬
cine, it is often fufficient, at leaft for the purpofes of life^ to know
the certainty of fbme particular phenomena, altho’ we cannot ac¬
count
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