nerves implicated. There is motor
paresis or paralysis, which may disappear either suddenly or
gradually, or may persist and be followed by atrophy of the muscles
concerned. In contrast to what is observed from pressure by tumours
and inflammatory products, twitchings and cramps are rare.

In _partial lesions of the cord_ the motor phenomena predominate.
Paresis extends to the whole of the motor area below the seat of the
lesion, but the weakness is more marked on one side of the body. The
distal parts--feet and legs--suffer more than the proximal--arms and
hands, and the extensors more than the flexors. The paresis develops
slowly, varies in extent and degree, and may soon improve. Vaso-motor
disturbances accompany the motor symptoms. Irritative phenomena, such
as twitchings or contractures, may come on later.

The deep reflexes, particularly the knee-jerks, may be absent at
first, but they soon return, and are usually exaggerated; a
well-marked Babinski response may appear later. Abolition of the
reflexes, therefore, does not necessarily indicate complete
destruction of the cord, but their return is conclusive evidence that
the lesion is a partial one. It is necessary, therefore, to defer
judgment until it is determined whether the abolition of the reflexes
is temporary or permanent.

Sensory disturbances may be entirely absent. When present, they are
incomplete, and are chiefly irritative in character. They may not
reach the same level as the motor phenomena, and the different sensory
functions are unequally disturbed in the areas corresponding to the
several nerve roots. There is sometimes a combination of hyperaesthesia
on one side and anaesthesia on the other.

Retention of urine is not always present even in those cases in which
the limbs are completely paralysed, as the fibres of one side of the
cord are sufficient to maintain the functions of the bladder. The
patient may be aware that the bladder is full, although he is unable
to empty it. Similarly, sensation in the rectum and anus may be
retained although the control of the sphincters is lost. Priapism may
be present, but tends to disappear.

In partial lesions, the difficulties of diagnosis are sometimes
increased by the occurrence of haemorrhage into the substance of the
cord, so that symptoms of generalised pressure are superadded to those
of the partial lesion. In time the symptoms due to the intra-medullary
haemorrhage pass off, but those due to t