This practical presentation from physical and pain medicine specialist Peter I-Kung Wu, MD, PhD, MPH, takes a deep dive into diffuse idiopathic skeletal hyperostosis (DISH), a problem that particularly affects men over 50, bringing stiffness and limiting range of motion. Wu describes essentials of the physical evaluation and shows radiographic images to illustrate secrets to distinguishing DISH from conditions with similar symptoms, such as ankylosing spondylitis. He discusses standard treatments; explains when to consider surgery; and gives valuable tips on related risks, such as spinal fractures.
Thanks so much, Christy, and, and uh I really appreciate the uh the liaison uh service for inviting me to present at this talk. Um, and I said, uh, Christy introduced you, uh, myself, I am, uh, trained in physical medicine and rehabilitation, uh, with subspecialty training in pain medicine. Uh, my practice is within a, uh, a group, uh, practice in the spine service with the UCS subpar of orthopedic Surgery. Where I see patients with spine and also musculoskeletal disorders and pain conditions and um our team helps to manage them uh non-operatively. Um, so a bit about my service, in many instances, our task to support the surgical side is to identify and treat pain generators, uh, in patients who may present from a range of conditions including neck and upper extremity, or low back and lower extremity pain. And often pain from spine pathology may present in not only the neck, mid back, or low back. Uh, but, or in classical radicular or dermatomal patterns, but also similar locations as uh shoulder or hip-related pain. Aside from using the physical examination and imaging findings, uh, the patient's history and description of their pain constitutes and provides a big, uh, part of the diagnostic information. When we evaluate patients, the anatomic location and pattern of pain are diagnosing characteristics that aid in identifying pain generators such as the inner vertebral disc, the facet, or sacroiliac joints, muscle or nerve. Also, a prominent characteristic a differential diagnosis is whether there are contributions of different types of pain, uh, namely neuropathic or neurogenic pain, versely, uh, versus mostly no susceptive pain, each having different qualities of pain that are distinct but can also overlap with the other type. Uh, the ways pain, uh, is aggravated and alleviated can further reveal where pain is coming from. And we always assess for signs and symptoms that raise concern for spinal pathology that may indicate the need for urgent treatment or surgical management. These include neurological deficits such as motor weakness, uh, deficits in sensation, coordination problems, difficulty with balance, um, falls, uh, difficulty with controlling bowel or bladder functions. Uh, and any signs that we detect on physical examination suggesting uh neural irritation. And of course, larger systemic signs and symptoms such as fever, chills, sweats, that might point to a bigger uh systemic issue. And more than determining pain generators, um, in other instances, we identify or confirm distinctive spinal conditions, uh, that might involve more unique care, which the case I'm presenting today helps to highlight. Uh, this is a case of an 82 year old man with a pertinent spinal history of cervical stenosis. Um, he's had, uh, spine surgery, including C3 to C5 laminoplasty, bilateral C4 to C5 laminotomies, a C6 laminectomy. He also has a history of low back issues including uh left L5 sciatica or radicular pain. And he presents with the chief complaint of neck and back stiffness, and that's first and foremost, it's, it's mostly stiffness, uh, followed by secondary complaints of pain in the neck and the back. Symptoms began over 5 years ago without trauma or any inciting event or activity. And again, his primary concern is being uh progressively decreased flexibility uh that he experiences in the entire spine along with reduced mobility. At the initial visit, he reports his present symptoms include intermittent sharp pain in the back of the neck, both sides of the low back, ranging anywhere from no pain up to 7 out of 10. Aggravators uh of his pain include moving his neck or bending over, and things that relieve his symptoms include just being in neutral position or just resting and not moving. He has no complaints of arm or leg pain or numbness, uh, or, or um weakness. Um, there is only a minimal complaint of numbness in the right thumb. And he reports some difficulty with with walking, but um no real uh falls or, or sort of legs giving up. Uh, referring back to when he had his, uh, spine surgery, he did well after his 2009 decompression at the neck. And uh his most recent follow-up, his last followup with the neurosurgery team in 2019. Um, at that, at that visit, he denied having any neck or back pain, uh, again, still noting the decreased spinal flexibility that he currently complains about. Workup from his visit showed, uh, known cervical neural foraminal stenosis, uh, but no cervical or thoracic compressive lesions. And then a note at that visit, imaging demonstrated auto fusion, so the fusion of vertebral segments or bones, uh, to each other spanning C3 to the C6 levels. On my examination when I saw him, um, Primarily, the remarkable finding was limited range of motion of the neck. Uh, there was no tenderness or usual, you know, palpable, uh, painful sights, uh, that, uh, that he was able to point out or that I was able to listen on physical examination. Uh, also a, uh, comprehensive evaluation of the neuro exam including motor strength, uh, sensation, um, as well as reflexes demonstrated no focal neurological deficits. Um, interesting, uh, interestingly, on his MRI, um, which was taken 3 years prior to his visit, a total spine MRI showed, uh, findings including partial osseous ankylosis from C3 to C7. Um, which we could appreciate on the far left image, uh, sagit view of the neck MRI. There are also large bridging anterior osteophytes among various, um, the usual various spondylotic findings, uh, such as arthritic changes, uh, flattered discs, etc. Uh, in the thoracic spine, In the second picture from the left, there were disc osteophyte complexes spanning T5 to T8. So this demonstrates as either flatter discs or bulgi discs with uh adjacent bone spurs next to those discs. And in the lumbar spine, there were anterior disc osteophyte complexes. Uh, here's seen in the next picture over on Sael View, um. Uh, also scattered among mild, moderate, uh spondylotic findings, uh, without a lot of arthritic changes in those facet joints. Um, and there was only mild spinal stenosis throughout the lumbar spine. Uh, given there was concern that the patient had some difficulty with walking, um, it was not necessarily, uh, corresponding to any, any significant spinal stenosis in the lumbar spine. While a subsequent lumbar MRI performed in 2023 demonstrated just more or progression of the degenerative disc disease compared to the 2021 MRI. It was really through current X-rays of the spine, which we ordered that were more revealing not only of the known osteocervical fusion from C3 to C7. Uh, but now these X-rays demonstrated flowing anterior osteophytes in the thoracic and lumbar spine that were consistent with diffuse idiopathic skeletal hyperostosis. Uh, there were also no findings of sacro ileitis to implicate, uh, a different type of condition. Um, of note, and I'm uh shown in this inset picture here, um, the cervical, uh, spine x-ray demonstrated the patient's C3 to C5 laminoplasty, and with these arrows, uh, or these, uh, these hardware findings here. Uh, just to share a comment. Is that those la laminoplasty involve the use of centerpiece mini plates. Uh, they were placed on the right side, which don't fuse the spine. So if there was a concern that this was fusion between uh cervical levels due to the hardware. It's not that the hardware actually fused the spine. Um, they're used, uh, posteriorly for laminar fixation, just to maintain and prop open, uh, the lamina to maintain the decompression and minimizing the risk of re stenosis of that spinal canal. So any finding or or uh prior comments that, that demonstrated fusion between C3 to C7 um was in fact auto fusion and not due to the surgery that the patient had. Along with this finding, um, consistent with DISH, there's certainly other conditions on the differential that may contribute to the patient's symptoms. Uh, we typically see a population where, um, their spine demonstrates, uh, age-related wear and tear or spondylosis. Uh, these findings could include facet arthropathy or arthritis. Common to the usual orthopedic conditions, we might find myofascial pain in the form of muscle tension or muscle knots. Um, The back pain and stiffness might also be the sequelae of the cervical laminoplasty the patient had, and this can actually also involve axial neck pain associated with skeletal and muscular asymmetry following a single-sided or unilateral laminotomy, which the patient had. Given the suspicion of um sort of a, a fusion or sclerosis, um, suggesting a different type of diagnosis, I referred to the patient to rheumatology first to evaluate for the possibility of an underlying inflammatory cause for the spinal ankylosis that we saw on the imaging, such as ankylosing spinylitis. But the, the evaluation and assessment from rheumatology. Um, demonstrated that they had no suspicion of this, uh, as symptoms were not classical for this. So to discuss what what diffuse idiopathic skeletal hyperartosis is, it's a systemic, it's non-inflammatory as compared to ankylosing spondylitis. Um, it's a condition of unknown ideology resulting in pathologic calcification and ossification of the emphases of the spine and other joints, and the emphases are the points where the tendons, ligaments, and joint capsules attached to the bone. So these can become calcified. And uh the condition can be characterized by seen on imaging, flowing ossification along the anterior, and to a lesser extent the lateral aspects of the spine, uh, bony proliferation called hyperroostosis at the sites of tendon and ligament attachments to the bone, ligamentous ossification, particularly the anterior longitudinal ligament that runs um along the anterior aspect of the vertebral spine. Uh, also paraspinal tissue fibrosis and antralateral extensions of fibrous tissue, as well as, uh, osteophytes that form around the joints in both the axial and the uh appendicular skeleton. A dish occurs in middle age to elderly men and women, where it's rarely reported in patients younger than 50 years old, though the condition is thought to start as early as the 3rd to 5th decades of life, and there's a male predominance. Uh, unfortunately, the ideology of this is still unknown or undefined, but has recognized associations, including increased age, male sex, um, history of diabetes, obesity, hyperlipidemia, hypertension, or atherosclerosis, congestive heart failure. Uh, hyperinsulinemia, hyperureassemia, gout, and an association with the HLABH, um, which is common in both DISH and diabetes. While the connection between the metabolic derangements and DISH is not completely demonstrated, there is thinking that a dysregulated hormonal and signal transduction pathway. May increase disease progression and suggest that the potential or the area where medical management might be to treat and reverse metabolic abnormalities such as diabetes, uh, obesity, hyperlipidemia, hypertension, um, to help slow the progression of DISH. Uh, although often asymptomatic because the auto fusion that we saw in this patient's neck, um, between vertebrae may limit otherwise painful motion or instability across these segments. Patients may still present with back pain, uh, prominent complaints about spinal stiffness and limited mobility. Uh, they may even complain about difficulty swallowing, uh, or upper airway obstruction due to the mechanical effect of large enough anterior cervical osteophytes, um, pressing on the esophagus or trachea, which, um, the picture on the right here shows that, um, the size of these osteophytes that may encroach on the uh soft tissues. Um, they may also have signs or symptoms of myeloradiculopathy due to, again, the stiffening or ossification of ligaments or bony structures resulting in spinal stenosis and pressure on the nerves. Beyond the spine, extraspinal manifestations may include the joint, uh, joint pain and stiffness, uh, from hypertrophic arthritis of joints not typically affected by the usual, uh, wear and tear arthritis. So these could be elbows, ankles, or shoulders, uh, versus what we more commonly see, uh, hippoA or knee way. Um, symptoms can also be enthysopathies that affect the tendons or the attachments to the bones at the elbows, the wrists, the pelvis, the knees, or the ankles. Exam findings may commonly reveal decreased range of motion or neurological signs of myelopathy or spinal stenosis. And the diagnosis, um, in terms of workup or uh diagnostic studies to do, um, is really confirmed with X-rays or radiographs, um, but, uh, CT can also be more sensitive. Uh, the classical radiographic diagnostic criteria were introduced by Resnick and colleagues in 1976. These include flowing antralateral calcification and ossification spanning at least four contiguous vertebral bodies, uh, relatively preserved disc spaces to distinguish it from spondylosis and just age-related changes. Uh, really no facet fusion or sacroiliac joint erosion, sclerosis, or fusion. And these criteria sought to differentiate dish specifically from more common findings of spondylosis as well as ankylosing spondylitis. Um, however, there is also concern in the field that, uh, using these classification criteria too stringently also presents the risk of missing early presentations of DSH, um, and concomitant degenerative disc changes or co-occurrence of ankylosing spondylitis should not con uh contradict a DISH diagnosis either. Uh, spinal features are best observed on the lateral uh X-rays, uh, showing the sagittal views of the spine. The most characteristic manifestation of dish is new bone formation, prominent in the anterior and the right aspect of the thoracic spine, particularly spanning T7 to T11. These produce a distinctive flowing pattern that you often see described by radiologists, uh, a flowing pattern of ossification with a bumpy spinal contour, uh. Uh, parallel to flowing candle wax. And dish has a propensity to occur on the right anterior thoracic spine. Interestingly, it's opposite the pulsating aorta, which is thought to provide a protective effect and a mechanical barrier preventing dish formation on the left side. Uh, studies have shown that it's thought, uh, to be this mechanism as patients with situitus inversis demonstrate dish on the left side of the thoracic spine. And in in the cervical and the lumbar spine, there can be symmetrical osteophytes and sandemohytes. Uh, disc spaces are also relatively preserved, and there's relative absence of significant degenerative changes, um, although there can be degeneration of the peripheral wall of the disc. Um, an ankylosis is more common in the thoracic than cervical or lumbar spine, but frequently incomplete. Uh, and again, there is no facet joint ankylosis or sacroilia joint erosion, sclerosis or osteo fusion, although sacro electroid bridging may be present. Um, additional patterns of spinal bone formation with dish are calcification or ossification in the anterior longitudinal ligament and proliferation, uh, or proliferative enthysopathy occurring where the anterior longitudinal ligament is attached to the vertebral body. Um, a radiolucent line between the deposited bone and the anterior, uh, vertebral surface is a diagnostic clue which we might see here on the, uh, the furthest left picture. It's not usually seen in most cases of ankylosing spondylitis, uh, shown here in the, uh, far bottom right uh picture here which has less striking new bone formation and generally a smoother spinal contour, which might be appreciated from this view, which uh showed that the anterior surfaces. Of those vertebral bodies are are generally smooth. Uh, posterior osteophytes are, are infrequent and small, uh, with a dish. Uh, although dish has been associated with increased incidence of ossification of the posterior longitudinal ligament and the ligament in flame, which may, um, both contribute to lead to spinal stenosis, and the, you know, the, uh, contribution of spinal stenosis to uh gait difficulty that this patient um presented with. Um, complications of dish can also include postoperative heterotopic ossification. And extraspinal findings include antyopathy and spur formation at those various sites. Iliac crest, a tuberosity, greater trochanter. Um, outside of the spine. So these features distinguish dish from other ankylosing conditions, um, but on the differentials such as uh advanced spondylosis and ankylosing spondylitis. In contrast to dish, spondylosis usually demonstrates prominent disc-related changes. Um, and facet degenerative changes that go together, uh, with, um, degenerative disc disease and usually thoracic anterior moduitudinal ligament is not affected as it is in dish. To differentiate or uh uh describe ankylosing spondylitis, um, it's a different ossifying arthropathy due to chronic and inflammatory disorder, rather than the non-inflammatory disorder with DISH. Um, this typically develops earlier in adulthood compared to DISH, but has a stronger association with HLAB27 and demonstrates Uh, distinctive, uh, different radiographic features. Here we show, um, Uh, features including sacroiliac joint involvement earlier on, with bilateral sacro ileitis demonstrating erosions, sclerosis, joint widening or narrowing, uh, leading to the classic description of ankylosis or stiffness. Uh, involvement typically progresses from the sacrum and goes up the spine, from lumbar to thoracic to cervical, and then findings on X-ray may demonstrate, uh, shiny corners, which is shown in picture two. We, uh, we can see that there is uh More opacity at the corner edges uh of the vertebral body that reflect reactive sclerosis, um, basically, it decrease in the density of the bone or bone hardening, secondary to inflammation and erosion at the superior and inferior vertebral implate anterior corners, which is where the attachment of the annuous fibrosis of the discs occur. These are actually referred to as ruinous lesions. And then in the third picture, this uh ankylosing sponles can also be followed by squaring of the anterior vertebral body margins, which these um The anterior aspects of these vertebral segments demonstrate really flat surfaces that demonstrate a loss of the normal concavity of the anterior border of the vertebral body, so they look particularly straight. Um, and in number 4, all of these findings, uh, listed above typically precede the development of the classic bamboo appearance of the spine, uh, which comes from vertebral body fusion by marginal syndeophytes, which are these ossifications of the annal fibrosis occurring along the lateral margins of the disc. And the ossifications where sendesophytes appear as thin curved repair of vertebral radioopaque spicules running parallel to the spine. They bridge adjoining vertebral bodies to give the impression of this undulating continuous lateral spinal border, uh, and it resembles a bamboo stem. And then lastly, there may also be a dagger sign, which is uh appearance of a radio dense line on AP view running along the central part of the spine reflecting ossification of the interspinous or supraspinous ligaments that extend, uh, which can extend all the way down to the sacrum. Uh, these AP and lateral views of, uh, lumbar X-ray are of a patient that I saw recently, uh, with findings of vertebral body squaring, which we kind of appreciate a little bit of this on the sagity view. Um, sendesophytes, which we're seeing on the sides or the lateral aspects of the spine, as well as, uh, which is kind of hazy here, but, uh, fusion of the bilateral SI joints or sacroiliac joints, um, that are compatible with ankylosing spondylitis. So the treatment for most cases of DISH is typically non-operative. Uh, these include the usual uh uh approaches including activity modification with particular precautions for hyperextension injuries. Um, PT can be involved, supportive bracing, analgesics for aches and pains, can also be a part of the management approach. Uh, at this time, there's, there's, uh, unfortunately, no direct disease modifying medications to address the condition or the progression, but, um, I think as, as referred to earlier, your work through primary care to provide appropriate management of associated metabolic conditions is, is very important and might seek to slow the progression. Um, operative treatment would be indicated for the sequelae, um, Such as decompression for myelloradiculopathy if the patient is exhibiting a lot of central stenosis or neuro foraminal stenosis, uh, affecting nerve function or the ability to maintain proper gait. Uh, the surgical interventions could also include osteophyte resection for, uh, osteophytes that push on um the esophagus, causing dysphagia or trachea, causing airway compromise. And surgical intervention can can be performed for stabilization and spinal deformity, and fractures. Um, also, as, as I sort of had, uh, pursued, a referral to rheumatology is beneficial for patients. Uh, to rule out or rule in other conditions, um, especially for ankylos spines to differentiate disease processes. Uh, of note, uh, rigid spinal segments due to the fusion, um, of the spine segments with each other may result in the reduced segmental motion due to the ankylosis found in dish, and they end up creating mechanically speaking, a long lever arm of spine, and that predisposes patients to unstable spine fractures and fracture patterns similar to those found in long bones such as the femur. And these may be commonly related to hyperextension injury. Um, even from low-level trauma such as a ground level fall, or even just having the position for elective surgical procedures, just the transfer and positioning of a patient with DSH on the table might result in um a spinal fracture. Um, there is and therefore, a higher risk of spinal cord injury. Perrospinal soft tissue atrophy and ligamentous calcification further increase that risk of fracture and stability, and patients don't have the the muscle conditioning to stabilize their spine. So, um, in ongoing care, there should be a higher clinical suspicion for fracture, and, uh, often CT and MRI scans should be performed whenever there's a spinal pain, a new occurrence of spinal pain or worsening spinal pain, and a history of trauma to evaluate for a cold fracture, um, even following low uh low energy trauma. So I'll end with this case here and then uh describe just a little bit about um our service with a general comment. If there are patients you think might benefit from seeing one of our team. Patients can be referred to uh see a PMNR spine specialist for spine evaluation, including imaging, um, electric diagnostic workup, uh, to evaluate or triage red flag symptoms I listed previously. Uh, or to pursue conservative management, including med medications, physical therapies, uh, all the way to the introduction of a spinal injections or interventions to relieve pain. Um, or also after they've had surgery for postoperative management of ongoing pain. RUCSS find clinic service probably at sites across the east, east, the north, and South Bay, in addition to uh our main clinics uh in San Francisco at Parnassus and the Mission Bay campus. And I, I've included just a slide here of contact information from my particular practice which is out of the Berkeley Outpatient Center, uh, right on San Pablo and Ashby, uh, including my name and, and sort of contact information to reach, uh, my team members, uh, which I'm happy to provide and hope, um, uh, Christy might be able to share with you all. So thank you for your attention and I'm happy to take any questions you may have.
