Diffuse Idiopathic Skeletal
Hyperostosis (DISH)
Diffuse idiopathic skeletal hyperostosis
(DISH) is a degenerative disorder of unknown etiology that frequently occurs in patients
over 60. The distinguishing characteristic of this disorder is the presence of excessive
ligamentous calcification and ossification of ligaments in the spine and extraspinal
locations. This disorder was often called Forrestier's disease. It was initially thought
this disorder may be a type of ankylosing spondylitis (AS), which it is not, and the two
should not be confused as their etiologies are entirely different. The prevalence of DISH
in the adult population is 12 to 28 percent.
Diagnosis of Diffuse Idiopathic Skeletal Hyperostosis
DISH has strict diagnostic
criteria, which distinguishes it from degenerative disc and joint disease and ankylosing
spondylitis. The following criteria have been established:
Flowing calcifications and
ossifications along the anterolateral aspect of at least four contiguous vertebral bodies
with or without osteophytes
Preservation of disc height in the
involved areas and an absence of excessive disc disease
Absence of bony ankylosis of facet
joints and absence of sacroiliac erosion, sclerosis, or bony fusion, however narrowing and
sclerosis of facet joints are acceptable.
Symptoms of Diffuse Idiopathic Skeletal Hyperostosis
DISH occurs most commonly in the
thoracic spine (97% of cases). It presents as laminated calcification and ossification
along the anterolateral aspect of the vertebral bodies, continuing across the
intervertebral disc spaces, which are relatively preserved. Ossification may extend to
involve both the right and left lateral aspects of the vertebral column, but is more
common and exuberant on the right side, presumably due to the inhibiting effect on
ossification by a left sided, pulsating descending thoracic aorta.
Lumbar spine changes in DISH
include hyperostosis along the anterior aspect of the vertebral bodies. With progression,
cloud-like increased bone density and pointed body excrescences develop. Additional
findings that can occur are close apposition of spinous processes or ossification of
interspinous ligaments, mild to moderate disc space narrowing, and apophyseal joint space
narrowing and sclerosis. Due to the ossification of the ligaments, which can include the
joint capsule, foraminal and central stenosis can occur at any spinal level.
In the cervical spine, bony
prominence may become so extensive that a thick bony plate is formed anteriorly and may
cause dysphagia. Alterations can occur on the posterior aspect of vertebral bodies, most
often in the cervical spine. These radiographic features include osteosclerosis of the
posterior vertebral margin, posterior vertebral osteophytosis, and calcification or
ossification of the posterior longitudinal ligament. Cervical myelopathy and cord
compression has been associated with patients demonstrating bony proliferation along the
posterior aspect of the vertebral bodies.
Extraspinal manifestations of DISH
are not uncommon and may even
be present in absence of significant spinal changes. These extraspinal changes consist of
hyperostosis at sites of tendon and ligament attachment to bone, para-articular
osteophytes, and ligament ossification. Generally in the peripheral skeleton, periosteal
spurs arising at the site of osseous attachment of the tendon are more prominent than true
calcification of the tendon itself. These ossifications extend into the fibres of the
tendon, particularly the Achilles' tendon and plantar aponeurosis, triceps, and quadriceps
tendons. Increased risk of heterotopic ossification is seen following Total Hip
Replacement.
Conventional
radiography clearly confirms the diagnosis of DISH.
CT & MRI better detect associated findings (e.g: ossification of
posterior longitudinal ligament) and complications (e.g: spinal cord compressive
myelomalacia)
Risk factors
associated with Diffuse Idiopathic Skeletal Hyperostosis
Greater body mass
Higher serum level of uric acid
Diabetes Mellitus
A majority of patients with DISH
have clinical symptoms, which include: stiffness, restricted motion, and tendinitis. The
discomfort is intermittent and nonradiating. Stiffness occurs most often in the morning
upon arising and dissipates within an hour of mild activity. The discomfort can return in
the late evening and become aggravated by sitting or cold, wet weather. These complaints
are initially apparent in the thoracolumbar spine. Several years after the initial onset
of symptoms, stiffness and pain can progress to involve other areas of the spine,
including the extremities. The disorder can progress to the point of causing significant
neurologic involvement, however the radiographic changes should also indicate probable
stenosis.
These patients generally respond
well to chiropractic treatment, NSAIDs & Physiotherapy (with the exception of patients
with significant spinal stenosis), but they require care on a continuing basis due to the
chronicity of the symptoms.
Other diseases can also be present along with DISH, The most common disorders
are spondylosis deformans and rheumatoid arthritis. |
