Definition. Casual and experimental cases in animals. Causes: Excision
of the thyroid, indigestions with fermentation, rheumatism, infection,
malaria, rachitis, want of hygiene, hereditary or developmental
irritability, microbian poisons. Symptoms: intermittent spasms with
semi-flexed limbs, tremors. Diagnosis: by the complete intermissions
of spasms, and by pressure on nerve or artery, rousing them. No fever.
Like spasms of ergot. Treatment: thyroid extract, grafting thyroid;
remove sources of irritation, antispasmodics, warm or tepid baths,
electricity.
_Definition._ Tetany is the name given to a limited contraction of a
group of muscles usually in the extremities occurring paroxysmally with
intervals, during which it may usually be roused into activity by
compression of the nerve or artery proceeding to the muscles in
question.
The disease has not been accorded a place in systematic works on
veterinary medicine, though cases have been recorded which are supposed
to have been of this nature, and in cases occurring in man and
associated with dyspepsia and gastric dilation, Bouveret and Devic have
extracted from the contents of the stomach a toxic substance which
caused tetanic convulsions in animals. The total removal of the thyroid
gland, or even of four-fifths of it (Eiselsberg), in the cat is found to
be invariably followed by tetany.
_Causes._ Beside the origin from the removal or general disease or
degeneration of the thyroid, it has been attributed to digestive
troubles, associated with fermentations and the production of toxic
matters, to rheumatism, infection and malaria, to rachitis and
unhygienic conditions. The systemic changes and trials of growth and
development, of pregnancy and lactation, seem to be factors in certain
cases. A peculiar irritable nervous organization transmitted by heredity
is undoubtedly a potent cause, and upon this, bacteridian, leucocytic
and other poisons operate so as to rouse the paroxysms.
_Symptoms._ There are usually prodromata in the shape of dullness,
prostration, weariness, and some dullness of the special senses. Fever
is commonly absent and the contractions tend to affect both flexors and
extensors, but as the force of the first predominates, the affected
member is usually held more or less rigidly semi-flexed. The spasm
appears suddenly, often taking occasion of some voluntary movement, and
may last for several minutes or hours. It is followed by an interval of
relaxation of equally uncertain duration. Though usually attacking the
limbs and causing the victim to walk on the toes, it may extend to the
face, neck or trunk, and constitute an intermittent trismus,
oposthotonos, or emprosthotonos.
_Diagnosis._ Tetany is to be distinguished from tetanus by the complete
intermissions of the spasms, and by the voluntary development of these
by compression of the presiding nerve or artery. Pressure on the nerve
arouses its excitability, and compression of the artery shutting off the
supply of blood from the disordered and susceptible muscles, tends to
increase their irritability. Ligature of an artery supplying healthy
muscles causes simple trembling of such organs. From the spasms of
cerebral, spinal or meningeal inflammation tetany is distinguished by
the absence of fever, and the complete intermissions of the paroxysms.
The spasms of ergotism bear the closest relation to those of tetany and
in the absence of proof of the ingestion of ergot, might well be
confounded with them.
_Treatment._ This consists mainly in doing away with the causes, when
these can be ascertained. Portions of thyroid may be grafted if complete
thyroidectomy has been performed, or thyroid extract may be given. In
the human subject recoveries have followed the expulsion of intestinal
worms, the cure of gastric dilation, dyspepsia, fermentations, diarrhœa,
rachitis, menstrual irregularity, or auto-intoxication. Fíré has seen
recovery follow the extraction of a carious tooth.
The spasms may be met by the internal administration of antispasmodics
(chloral, belladonna, bromides, opiates), and the external application
over the affected muscles of anodynes and antispasmodics (belladonna,
opium, chloroform, oil of cajeput, oil of peppermint, menthol, etc.).
Warm or tepid baths are often of great value and a mild electric current
has been found useful.