s the wound is aseptic or has healed.

#Secondary Suture.#--The term secondary suture is applied to the
operation of stitching the ends of the divided nerve after the wound has
healed.

_Results of Secondary Suture._--When secondary suture has been performed
under favourable conditions, the prognosis is good, but a longer time is
required for restoration of function than after primary suture. Purves
Stewart says protopathic sensation is sometimes observed much earlier
than in primary suture, because partial regeneration of axis cylinders
in the peripheral segment has already taken place. Sensation is
recovered first, but it seldom returns before three or four months.
There then follows an improvement or disappearance of any trophic
disturbances that may be present. Recovery of motion may be deferred for
long periods--rather because of the changes in the muscles than from
want of conductivity in the nerve--and if the muscles have undergone
complete degeneration, it may never take place at all. While waiting for
recovery, every effort should be made to maintain the nutrition of the
damaged nerve, and of the parts which it supplies.

When suture is found to be impossible, recourse must be had to other
methods, known as nerve bridging and nerve implantation.

#Incomplete Division of a Mixed Nerve.#--The effects of partial division
of a mixed nerve vary according to the destination of the nerve bundles
that have been interrupted. Within their area of distribution the
paralysis is as complete as if the whole trunk had been cut across. The
uninjured nerve-bundles continue to transmit impulses with the result
that there is a _dissociated paralysis_ within the distribution of the
affected nerve, some muscles continuing to act and to respond normally
to electric stimulation, while others behave as if the whole nerve-trunk
had been severed.

In addition to vasomotor and trophic changes, there is often severe pain
of a burning kind (_causalgia_ or _thermalgia_) which comes on about a
fortnight after the injury and causes intense and continuous suffering
which may last for months. Paroxysms of pain may be excited by the
slightest touch or by heat, and the patient usually learns for himself
that the constant application of cold wet cloths allays the pain. The
thermalgic area sweats profusely.

Operative treatment is indicated where there is no sign of improvement
within three months, when recovery is arrested before complete
r