Trepanning is the
medical process of drilling or cutting a hole into the skull in order to
relieve pressure on the brain tissue, lift a compression fracture of the
skull, or remove a blood clot on the brain. If a person had a concussion
with depression of the skull bone, that depressed area would need to be lifted
or removed and then the clot under the concussion removed to alleviate trauma
The process is
documented to have been performed as far back as 4000 years ago by the Inca
Indians of Peru. If you would like more information on this procedure
and the history, please do a search for the words: trephine, Inca,
neurosurgery, trepanning, trepan on google.com.
tree-panning), as was frequently practiced in America during the 1800's, was
performed with an instrument called a trephine (pronounced: tray-feene or
tree-fine) which actually saw cuts a circular hole in the scull.
The scalp over the skull
is first incised with a scalpel, a flap laid back, and the hole bored or saw
cut by a twisting motion of the trephine. In some types of trephines,
there is a center drill which holds and guides the outer cutting edge of the
saw. There are two types of trephine saws, the earlier crown type and
the later Galt type.
Scalpel for tissue incision
Trephine with 'Galt' style saw
Another instrument used
for this procedure is the Hey saw, which has both a straight and curved tooth
edge for cutting into the skull.
Hey saw used
to cut into the skull bone
piece of bone, about the size of a nickel is then removed by using one
end of a lenticular or bone rasp to lift out the bone, then the
edges of the bone would be smoothed with the rasp.
Bone file for smoothing edges and
lifting out parts of bone.
Any bone dust
could then be removed with the bone brush before cutting into the dura,
which is the outer covering of the brain.
Bone brush to remove bone sawdust
from the cutting site.
Examples of American cased trepanning sets
Wiegand & Snowden, c. 1830
Fig. 1: Cased Trepanning set
Fig. 2: Trepanning instruments
In figure 1, is a cased trepanning set
by Wade and Ford.
The set contains a lenticular bone rasp, scalpel, Hey saw, crown type trephine,
wood handle for the trephine, and both a crown and a Galt type trephine
Fig. 3: Trephanning cased set
Fig. 4: instruments from case
The set in figure 3 is by
Gemrig, contains a bone brush and is missing
the scalpel. Figure 4 shows the individual instruments from the Gemrig
set. The trephine is assembled with a crown type trephine saw.
These type of cased sets were issued to
the Union surgeons during the Civil War and made by makers like Gemrig.