TREPHINING THE FRONTAL SINUSES. 
67 
and exuberant granulation is only seen in rare cases, and is due to tumour 
formation or one of the specific inflammations. 
In oxen the nasal discharge is usually blood-streaked at first, and only 
becomes purulent at a later period. If the frontal sinus be affected, 
signs of brain disturbance, like dulness, lowering of the head, giddiness, 
falling or convulsions, may appear. In unilateral disease the animals 
usually hold the head obliquely towards the diseased side. 
Similar sensory disturbance is seen in dogs and sheep when the frontal 
sinuses are affected. Dogs are then apt to be very snappish. 
Recovery never occurs spontaneously, though death from extension of 
the process to the brain or from septicaemia is rare. A fatal termination 
is commoner in oxen. In most cases the disease becomes chronic; in 
oxen the pus occasionally breaks through at the base of the horn. 
Treatment must be preceded by trephining. The cases said to have 
been cured by disinfectant inhalations are open to considerable doubt. 
The contents of the sinus are washed out, a disinfecting solution, such 
as carbolic, sublimate, or creolin, injected, and the opening closed with 
a plug of tow or jute. Irrigation must be repeated daily, until the nasal 
discharge ceases. The operation wound soon closes completely. 
TREPHINING THE SUPERIOR MAXILLARY AND FRONTAL 
SINUSES. 
Trephining the super-maxillary and frontal sinuses has been under¬ 
taken from very early times. It was frequently vainly employed for 
the cure of glanders, and has occasionally been of service in aiding 
diagnosis in cases of suspected glanders, for which purpose it is com¬ 
mended by Haubner as affording evidence of the condition of the lining 
membrane of the sinuses, and explaining any dubious discharge. But 
trephining is still more useful in the treatment of such local affections 
of the facial sinuses as chronic catarrh, in removing tumours and foreign 
bodies, and in punching out certain molars. 
Various instruments are used for removing portions of bone from the 
walls of the skull. 
(1.) The trephine, a circular-shaped saw, which is either affixed to a 
stock similar to a carpenter’s (stock trephine, fig. 40), or to a handle 
(hand trephine, fig. 41). Usually the latter simple form is used. The 
crown, a steel cylinder of varying size, which forms the saw, is smooth 
on its external surface, differing in this respect from those formerly in 
use, which were conical, and provided externally with sharp saw teeth to 
allow of their entering the bone. In the centre of the crown stands the 
centre pin, a piece of steel which can be fixed by means of a screw, and 
caused to project somewhat, beyond the cutting edge of the crown 
(2.) The elevator (fig. 42) carries at one end a ring, by which it is 
f 2 
