ith nervous
symptoms referable to pressure on the cord. This disease is now known
to be tuberculous. It may occur at any period of life, but in at least
50 per cent. of cases it attacks children below the age of ten and
rarely commences after middle life.

#Morbid Anatomy.#--The tuberculous process may affect any portion of
the spine, and as a rule is limited to one region; several vertebrae
are usually simultaneously involved. The disease may begin either in
the interior of the bodies of the vertebrae--tuberculous
osteomyelitis--or in the deeper layer of the periosteum on the
anterior surface of the bones--tuberculous periostitis.

_Osteomyelitis_ is the form most frequently met with in children. The
disease commences as a tuberculous infiltration of the marrow, which
results in softening of the bodies of the affected vertebrae,
particularly in their anterior parts, and, as the disease progresses,
caseation and suppuration ensue, and the destructive process spreads
to the adjacent intervertebral discs. In some cases a sequestrum is
formed, either on the surface or in the interior of a vertebra. The
pus usually works its way towards the front and sides of the bones,
and burrows under the anterior longitudinal (common) ligament. Less
frequently it spreads towards the vertebral canal and accumulates
around the dura, causing pressure on the cord.

The compression of the diseased vertebrae by the weight of the head and
trunk above the seat of the lesion, and by the traction of the muscles
passing over it, produces angling of the vertebral column. The
anterior portions of the bodies being more extensively destroyed, sink
in, while the less damaged posterior portions and the intact articular
processes prevent complete dislocation. In this way the integrity of
the canal is maintained, and the cord usually escapes being pressed
upon. The spinous processes of the affected vertebrae project and form
a prominence in the middle line of the back. When, as is usually the
case, only two or three vertebrae are implicated, this prominence takes
the form of a sharp angular projection, while if a series of vertebrae
are involved, the deformity is of the nature of a gentle backward
curve (Fig. 210).

[Illustration: FIG. 210.--Tuberculous Osteomyelitis affecting several
vertebrae at Thoracico-lumbar Junction.]

The _periosteal form_ of vertebral tuberculosis is that most
frequently met with in adults. The disease begins in the deeper