Improvements in the Means Employed in the Operation of Trephining.
Year: 1897

page_text: Date of Application, 9th Jan., 1897
Complete Specification Left, 9th Oct., 1897-Accepted, 20th Nov., 1897
PROVISIONAL SPECIFICATION.
Improvements in the Means Employed in the Operation of
Trephining.
I, ALFRED SYKES of Spring Place Mill, Spring Wood Street, Huddersfield
Yorkshire, Electrical Engineer do hereby declare the nature of this invention to be
as follows:
This invention refers to instruments employed in the operation of trephining or
cutting out portions of the skull, and my improvements consist in constructing and
arranging a cranial osteotome which shall be well adapted for cutting in any direction
with greater truth and ease than with ordinary instruments and without liability of
injuring the brain, and also to provide means in conjunction with cutters, for depressing
the dura mater clear of said cutters as they pierce or cut through the skull when
removing a small disc of bone to admit the aforesaid osteotome, and thus avoid injury
to that membrane.
According to my invention I employ a suitable cutting head supporting loosely
therein a sleeve or tube in which is secured one end of the cutter and the end of
a flexible shaft for rotating said sleeve or tube and cutter. Below the cutting head
and attached thereto is a button or small disc, rounded on its underside and having
the free end of the cutter journalled in a bearing or footstep formed therein, the
space between the button and cutting head being sufficient to receive the full
thickness of skull and allow clearance and forming a gap in which the cutter works.
The said button is adapted to engage and ride over the dura mater or brain and
against the skull and acts as a guide to the working of the instrument. To the
cutting head is attached, in any suitable manner, a handle, which is arranged at
right angles to the cutter and at the rear thereof,. said handle being bent or curved
at one part of its length so that when grasped by the hand the latter will be clear
of the skull. On each side of said handle and close to the cutting head I mount
two or more sinall pulleys or bowls which are adapted to ride over the skull to give
ease of movement and guidance to the instrument and act also as a pivot about which
the osteotome can be raised or lowered, as required, when cutting; the leverage
obtained giving to the operator considerable power over the manipulation of it.
The handle being at right angles to the cutter gives complete control over the
instrument, enabling it to be guided accurately in any direction, and the pressure
necessary to force it forward can be applied in a direction lineable with the cut to be
taken. The cutter employed is preferably a three sided or triangular one, but other
forms of cutters, spiral or otherwise, may be employed.
The cutting of a small dise of bone out of the skull to allow for the introduction
of the cranial osteotome is performed by a series of three or other suitable number
of cutters mounted on a small head which carries in front of each cutter a guard or
foot supported in slotted or self adjusting bearings or brackets and having springs
thereon or acting therewith. These guards enter the circular cut made in the skull,
being forced in by the springs, which are in compression, and when the cutters have
penetrated through or nearly through the skull, the guards, still under pressure of
the springs, are forced or break through and bear against the brain or dura mater
which is thus depressed and held clear of the cutters, whereby the latter can do no

page_text: injury to or cut that membrane. The guards are suitably rounded or protected at
their lower ends.
Dated this 7th day of January 1807
TASKER & CROSSLEY,
Huddersfield, Agents for the Applicant.
Improvements in the Means Employed in the Operation of
Trephining.
I, ALFRED SYKES, of Spring Place Mill, Spring Wood Street, Huddersfield,
Yorkshire Electrical Engineer, do hereby declare the nature of this invention and
in what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement:―
This invention refers to instruments employed in the operation of trephining or
cutting out portions of the skull, and my improvements consist in constructing and
arranging a cranial osteotome which shall be well adapted for cutting in any direction
with greater truth and ease than with ordinary instruments and without liability of
injuring the brain; and also to provide means in conjunction with cutters for
depressing the dura mater clear of said cutters as they pierce or cut through the
skull when removing a small disc of bone to admit the aforesaid osteotome, and thus
avoid injury to that meinbrane.
According to my invention I employ a suitable cutting head supporting loosely
therein a sleeve or tube, in which is secured one end of the cutter and the end of
a flexible shaft for rotating said sleeve or tube and cutter. Below the cutting head
and attached thereto is a button or small disc, rounded on its underside and having
the free or lower end of the cutter journalled in a bearing or footstep formed therein,
the space between the button and cutter head being sufficient to receive the full
thickness of skull and allow clearance, and forming a gap in which the cutter works.
The said button is adapted to engage and ride over the dura mater and against the
skull and acts as a guide to the working of the instrument. To the cutter head is
attached, in any suitable manner, a handle, which is arranged at right angles to the
cutter and at the rear thereof, said handle being bent or curved at one part of its
length so that when grasped by the hands the latter will be clear of the skull.
each side of said handle and close to the cutter head I mount two or more small
pulleys, bowls or discs which are adapted to ride over the surface of the skull to
give ease of movement and guidance to the instrument and act also as a fulcrum
about which the osteotome can be raised or lowered, as required, when cutting, the
leverage obtained thereby also giving to the operator considerable power over the
manipulation of the instrument.
On
The handle being at right angles to the cutter gives complete control over the
instrument, enabling it to be guided accurately in any direction, and the pressure
necessary to force it forward can be applied in a direction lineable with the cut to be
taken. The cutter employed is preferably a three sided or triangular one, but other
forms of cutters, spiral or otherwise, may be employed.
The cutting of a small disc of bone out of the skull to allow for the introduction
of the cranial osteotome is performed by a series of three or other suitable number of
cutters mounted on a small head which carries in front of each cutter a guard or foot
supported in slotted or self adjusting bearings or brackets and having springs thereon
or acting therewith. These guards enter the circular cut made in the skull being
forced in with the cutters and when the skull has been penetrated or practically so,
the guards, by means of the springs, are forced down and bear against the dura

page_text: mater which is thus depressed and held clear of the cutters whereby the latter can do
no injury to or cut that membrane.
In order that my said Invention may be fully understood, reference is hereafter
had to the accompanying drawings, forming a part of this Specification, in
which :-
Fig. 1 is enlarged elevation, partly in section, of my improved cranial osteotome for
cutting the skull or bone.
Fig. 2 is perspective view thereof.
Fig. 3 is elevation of supplementary trephine for removing a small disc of bone to
admit the osteotome; and
Fig. 4 is plan of same taken on line 1-2.
Referring firstly to Figs. 1 and 2, letter a represents the cutter head or bearing
for supporting and carrying the cutter bone end of which is secured by screws b¹
within the sleeve or tube c fitting loosely in the cutter head, so as to rotate freely
therein. The said tube is supported by a flange or collar e¹ thereon which rests upon
the upper end of the cutter head, and is secured, in said cutter head by a screwed
cap or nut a¹.
A ball bearing may be employed for the tube to rotate on, if desired.
In the upper-end-of-tube-c-is-secured, by screw d, the end of a flexible shaft d¹ for
rotating said tube and the cutter b. Below the cutter head a, and carried by an
arm or extension a², is a button or small disc a³ rounded on its underside and having
the free or lower end of the cutter b journalied in a bearing or footstep formed
therein; the space between the button and the cutter head a being sufficient
to receive the full depth of the skull and allow clearance, and forming a gap in which
the cutter works.
The undersurface of the button a³ is adapted, when trephining, to engage or press
upon and ride over the dura mater and prevent injury thereto.
The cutter head a has attached thereto, or formed integral therewith, a handle e
arranged at right angles, or approximately so, to the cutter band at the rear thereof,
said handle, at a short distance from the cutter head, being bent or curved upwardly
to a higher plane, so that when grasped by both hands, they will be quite clear of
the skull or bone being operated on. On each side of said handle e, and close to the
cutter head, I mount small pulleys, bowls or discs e¹, e¹, which are adapted to
ride over the surface of the skull to give ease of movement to and assist in guiding
the instrument and which act also as a pivot or fulcrum about which the osteotome
can be raised or lowered to the degree required in operating, the leverage obtained
giving to the operator considerable power over the manipulation of the instrument,
and facilitating and affording greater accuracy in the work. By arranging the
handle e at approximately right angles to the cutter, complete control is given over
the instrument, enabling it to be guided accurately in any direction while the pressure
necessary to force it forward can be applied in a direction exactly lineable with the
cut to be made.
In Fig. 2 the application of the osteotome is shewn, letter f representing the skull
and f¹ the dura muter. The instrument is held in the hand and the cutter b driven
by the flexible shaft d from any suitable motor. The cutter employed is, preferably,
a three sided or triangular one, as shewn, but other forms of cutters, spiral or
otherwise, may be employed.
In making the operation, a small disc of bone must first be removed from the
skull before the cranial osteotome, above described, can be introduced to cut
the section of skull required. To remove such small disc of bone I employ the
supplementary trephine shewn at Figs. 3 and 4, which comprises three or one or
other number of cutters y secured at equal distances apart to the cutter head h secured
in and carried by a barrel or casing i, as shewn, and in which it is free to rotate.
Side by side with each cutter and in front or advance thereof, are arranged guards j
secured to the cutter head h by screws k, k¹, passed through slots in said guards,
which admit of their being slided vertically within the limits of the slots.
.
Spiral springs l, attached at one end to screws secured to the guards j and at

page_text: the opposite ends to the screws ¹, secured to the cutter head, are employed to act in
résistance to the upward movement of the guards, which normally project below the
cutting edges g₁ of the cutters. Loosely supported in the barrel or casing i is
a spindle or pin m which extends through the cutter head and terminates in a sharp
point, the upper end of said spindle projecting through the top of the barrel or
The lower
casing and having the flexible shaft d' secured thereto by screws d.
portion of the spindle m has a flat m¹ on one side (see Fig. 4) which leaves a small
space between it and the opening through the cutter head. Into this space project
screws m², screwed through the cutter head, which secure the said cutter head and
spindle together rotatively, but permit of independent endwise movement of the
latter. The spindle m is secured and supported in the barrel or casing i in
the following manner-At the upper end of the spindle m is a collar or
enlargement m³ having an annular groove or neck formed therein into which project
the ends of two small handles o passed through L shaped slots p in the barrel i and
then screwed through a sleeve or washer q loosely surrounding the collar or
enlargement m³.
The barrel or casing i is provided with handles by which to hold the instrument
when operating.
In applying the trephine, the operator first forces down the handles o the length
of the slots p against the resistance of a spiral spring s, confined between the washer q
and screws t screwed through the sides of barrel i, a slight lateral pressure then forcing
them into the horizontal portions of the slots as shewn in Fig. 3, wherein they are
held until released. This action forces down the spindle or pin m to the position
shewn in Fig. 3 to bring the point of same below the cutters so that it can be forced
into the skull at the position desired. Motion is thereupon given to the spindle by
the flexible shaft and the cutter head and cutters are thereby rotated. The
operator, in pressing down the trephine to bring the cutters to bear on the skull
causes the guards j to be forced upward by contact with the skull whereby the cutting
edges of the cutters are exposed and at once commence cutting, pressure being
continued on the handles until the cutters have penetrated the skull.
Immediately the bone is cut through, the resistance to the guards ; is removed
and they are drawn down by the springs to the position, shewn at Fig. 3, thereby
depressing the dura mater clear of the cutters and covering the cutting edges thereof,
which, therefore, can do no injury to the membrane.
At any moment, during the above preparatory operation, the operator can withdraw
the point of the spindle m to a position above the cutting edges of the cutters and
clear of the skull by moving the handles o out of the horizontal portion of the
slots p, the springs forcing up the spindle immediately the handles are thus
released.
By this means all danger of injuring the dura mater by the pointed centreing
spindle or pin is avoided.
On withdrawing the supplementary trephine after cutting out the small disc of
bone, the cranial osteotome can then be introduced into the opening so made, and
a cut taken in any direction and to any extent marked out.
The guards
suitably rounded at their lower ends.
are
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is
Firstly. A cranial osteotome provided with a handle arranged approximately at
right angles to the cutter and, preferably, carrying a pulley or pulleys or discs on
each side thereof near to the cutter head, substantially as herein shewn and described
and for purposes set forth.
Secondly. The improved trephine comprising a rotary cutter head having a cutter
or cutters secured thereto and carrying moveable guards for covering and exposing
the cutting edges of the cutters, as required, and a pointed centreing spindle or pin
secured rotatively to the cutter head and adapted to be moved longitudinally into and

page_text: out of position, all arranged and operating in the manner and for the purposes
substantially as herein shewn and described.
1005
TASKER & CROSSLEY,
Huddersfield, Patent Agents.