are
situated in the lumbar enlargement.

In the great majority of cases of spinal disease or injury coming
under the notice of the surgeon the symptoms are bilateral, that is,
are of the nature of paraplegia, and the whole of the body below the
level of the segment affected is involved in the paralysis. Lesions
affecting only one-half of the cord are rare and give rise to symptoms
which are exceedingly complicated. When the lesion implicates the
nerve-roots only, the symptoms are confined to the area supplied by
the affected nerves.

INJURIES OF THE SPINAL MEDULLA OR CORD

As the clinical importance of a spinal injury depends almost entirely
on the degree of damage done to the cord, we shall consider injuries
of the cord before those of the vertebral column. They will be
described under the headings: Concussion of the Cord; Traumatic Spinal
Haemorrhage; Total Transverse Lesions; Partial Lesions of the Cord and
Nerve Roots; and "Railway Spine."

#Concussion of the Spinal Cord.#--Concussion of the cord is now
regarded as a definite entity closely resembling concussion of the
brain. In some cases, the underlying lesion is of a temporary
character, usually in the form of a vascular disturbance such as
oedema or vascular engorgement, and possibly an arterial anaemia; in
other cases there is definite evidence of injury, of the nature of
contusion, minute haemorrhages and blood-staining of the cerebro-spinal
fluid. It must be clearly stated, that concussion of the cord may be
attended with an immediate arrest of all its functions closely
resembling the condition following upon complete crushing of the
cord--total transverse lesion,--and it may be impossible to
differentiate between the two conditions until two or more days have
elapsed after the accident; it is usual, however, in concussion, as
contrasted with crushing of the cord, that although motor conduction
may be completely abolished, sensation is only impaired and evidence
of sensory conduction can usually be elicited. If the lesion is merely
a concussion, the functions of the cord will be restored within a day
or two, first to full sensation and then to full motor power.

A classical instance is that of a late Governor-General of India, who
on being thrown in the hunting-field was found to be paralysed in all
four extremities; Paget diagnosed a total transverse lesion of the
cervical cord with the necessary inference that it would inevitably
have a fatal termi