OALL / DISH (Cervical Hyperostosis)

Definition. Diffuse idiopathic skeletal hyperostosis (DISH, Forestier disease) is a systemic, non-inflammatory enthesopathy that lays down "flowing" ossification along the spinal ligaments and the peripheral entheses, sparing the disc and the synovial joints. OALL, ossification of the anterior longitudinal ligament, is its cervical expression. It grows anteriorly, so it compresses the pharynx, oesophagus and airway rather than the cord.

Who. Radiographic prevalence rises with age, from roughly 10 percent over 50 years to up to 25-30 percent over 70 years in autopsy and CT cohorts. Men are affected about twice as often as women (2:1), and the disease is rare under 40 years.

The metabolic link. DISH is strongly linked to metabolic syndrome: type 2 diabetes, obesity and hypertension. It is increasingly viewed as a metabolic bone phenotype rather than simple "wear and tear".

Where. Cervical osteophytes are most marked at C3-C6.

How often it causes dysphagia. Not reliably established. Almost every published series is a collection of symptomatic cases with no denominator, so the widely quoted percentages have nothing behind them. The measurable quantity runs the other way: of 455 patients referred with dysphagia, 51 (11.2%) met Resnick criteria for DISH (García Callejo, PMID 31122675). That is the proportion of dysphagia caused by DISH, not the proportion of DISH causing dysphagia, and the two are routinely swapped.

The anterior longitudinal ligament. A broad ligament covering the front of the vertebral bodies, it prevents hyperextension. In DISH it ossifies but spares the annulus fibrosus and nucleus pulposus, unlike in ankylosing spondylitis.

Swallowing. The act runs in three phases:

1. Oral - the bolus is prepared
2. Pharyngeal - the pharynx constricts, the hyoid elevates and the epiglottis inverts
3. Oesophageal - peristalsis

Where OALL interferes. OALL disrupts the pharyngeal phase, either by physically blocking epiglottic inversion or by narrowing the pharyngeal space. A mechanical block to epiglottic inversion leads to silent aspiration and pneumonia.

The mirror image. OPLL, ossification of the posterior longitudinal ligament, forms behind the vertebral bodies and grows into the spinal canal, compressing the cord and causing cervical myelopathy. OALL grows anteriorly and causes dysphagia and airway obstruction without myelopathy. The two are mirror-image problems and a classic exam pairing.

What they share. Both are ectopic-ossification disorders within the DISH / metabolic ossification spectrum, and the two can coexist in the same patient, anterior and posterior ossification together. OPLL is notably more common in East-Asian populations.

OPLL in brief. OPLL is classified by morphology into continuous, segmental, mixed and localised (circumscribed) types. Multilevel disease is typically decompressed posteriorly by laminoplasty, and dural ossification and CSF leak are recognised hazards of anterior resection. The dedicated OPLL topic develops all of this.

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Resnick and Niwayama criteria. The gold standard for diagnosing DISH and distinguishing it from ordinary spondylosis:

1. Flowing calcification along the anterolateral aspect of at least 4 contiguous vertebral bodies
2. Preservation of disc height in the involved segments, and absence of extensive radiographic changes of degenerative disc disease (vacuum sign, marginal sclerosis)
3. Absence of apophyseal joint ankylosis or of sacroiliac joint erosion, sclerosis or fusion

DISH or ankylosing spondylitis. The third criterion is there to exclude ankylosing spondylitis (AS). The two diseases separate on age, the sacroiliac joints, the disc and HLA-B27:

Dysphagia severity. Graded from incidental to severe:

• Grade 1 - asymptomatic, an incidental finding
• Grade 2 - mild dysphagia, solids only; managed with dietary modification
• Grade 3 - moderate dysphagia, liquids and solids, with weight loss; needs investigation
• Grade 4 - severe dysphagia with aspiration risk; tube feeding or surgery indicated

Symptoms. Dysphagia, the sense of food sticking, is the most common presenting symptom of cervical OALL (a minority of all cervical DISH). The other symptoms:

• Globus - the feeling of a lump in the throat
• Dysphonia - hoarseness, from recurrent laryngeal nerve compression or vocal cord oedema
• Airway symptoms - stridor and sleep apnoea
• Dyspnoea - rare, caused by laryngeal oedema or a massive C3 osteophyte compressing the glottis
• Stiffness - decreased cervical range of motion

Examination. A hard, bony mass is palpable in the posterior pharynx; beware the gag reflex. The neck is stiff and has lost extension. The neurological examination is usually normal, because OALL grows out of the canal, not into it.

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The decision. An incidental finding is observed. Symptoms start a workup whose first job is to exclude malignancy or stricture; only when that confirms extrinsic compression does the severity of the dysphagia choose between conservative care and anterior osteophytectomy.

Non-operative care. First-line treatment:

• Dietary modification - soft foods and thickened fluids, with speech pathology involvement
• NSAIDs - to reduce soft-tissue inflammation around the osteophytes
• Steroids - a short course for an acute flare of dysphagia
• Review - monitor weight and signs of aspiration

Surgery. Osteophytectomy is reserved for severe dysphagia, weight loss or aspiration, or for airway compromise.

The operation. Anterior cervical osteophytectomy resects the anterior bony mass to decompress the oesophagus, through a standard Smith-Robinson anterior cervical approach.

Positioning. Supine, with the neck slightly extended, in a Mayfield head clamp or on a horseshoe. Be careful: hyperextension can fracture the fused spine.

Step by step.

1. Incision - a transverse skin incision at the level of the osteophyte, confirmed with fluoroscopy
2. Dissection - deep dissection medial to the carotid sheath and lateral to the trachea and oesophagus
3. Exposure - the prevertebral fascia will be tight over the mass, and identifying the "valley" between the osteophyte and the disc space is crucial
4. Adhesions - chronic inflammation often leaves the oesophagus adherent to the tip of the osteophytes, so the risk of perforation is significantly higher than in a standard ACDF. Peel it off gently with a peanut dissector or a wet Raytec
5. Resection - a high-speed diamond burr or a Leksell rongeur takes down the "peaks" over the vertebral bodies; at the "valleys" over the discs, take care not to violate the annulus
6. Limits - resect flush with the anterior margin of the vertebral body, and do not chase lateral osteophytes near the foramen transversarium (vertebral artery risk)
7. Disc sparing - do not enter the disc space
8. Bone wax - apply it to the bleeding cancellous surface
9. Closure - a deep drain is essential; close platysma and skin

Fusion. Generally not indicated unless there is pre-existing instability, because fusion increases adjacent segment disease.

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Persistent dysphagia. The table leaves out one further complication of osteophytectomy: swallowing that stays difficult after the operation.

The airway first. Monitor for retropharyngeal haematoma or oedema, watching for stridor. Nasogastric feeding may be needed after an oesophageal repair or with severe oedema. If there are dural or oesophageal concerns, repeat a contrast swallow before oral intake.

Dysphagia. Success is high for dysphagia resolution, with improvement in about 95 percent of operated patients in the largest pooled series, a series built mostly of case reports (see the Harlianto review below). Eating ability and quality of life improve significantly.

Aspiration. Aspiration may not resolve if its cause was neurological or permanent muscle damage.

What it is. DISH leaves a rigid, brittle, "bamboo-like" spine, fused and often osteoporotic, as ankylosing spondylitis does. A fracture in it runs transversely across the entire ossified column, like snapping a stick of chalk, usually as a hyperextension injury through a disc space or vertebral body. The long, stiff lever arms on either side behave like long-bone segments, so this is an inherently unstable three-column injury, even after trivial or low-energy trauma such as a fall from standing or a minor knock.

Why it is dangerous.

• It is frequently missed or diagnosed late, obscured by the ossified mass and the pre-existing deformity on plain films
• High rates of spinal epidural haematoma, cord injury and mortality; neurological deterioration can be delayed
• DISH fractures cluster at the thoracolumbar junction (Harlianto meta-analysis), whereas AS fractures favour the mid-thoracic spine

Management. Treat new spinal pain after any trauma in an ankylosed-spine patient as a fracture until excluded.

• Imaging - full-length CT of the whole spine, looking for non-contiguous fractures; add MRI for neural, ligamentous or epidural injury, that is when there is a neurological deficit or a suspected disco-ligamentous hyperextension injury (Tavolaro), balancing the risk of moving the patient
• Handling - immobilise and transfer in the patient's own fixed posture. Never force the neck or spine straight: this can displace the fracture and injure the cord, the same hyperextension caution that applies to operative positioning
• Definitive treatment - usually long-segment instrumented stabilisation, because long lever arms and poor bone make short constructs fail. Many of these fractures need surgery even when they look "minimally displaced"

General fracture classification and fixation are developed in the cervical-spine-fracture, subaxial-cervical-fractures, thoracolumbar-fractures and ankylosing-spondylitis topics.

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Global epidemiology

• Radiographic DISH is common worldwide in older adults: roughly 10 percent over 50 and 25-30 percent over 70, with consistent male predominance across European, North American and Asian CT/autopsy cohorts.
• Population studies repeatedly tie DISH to metabolic syndrome, so prevalence tracks with regional obesity and type 2 diabetes burden.
• Symptomatic cervical OALL (dysphagia or airway obstruction) remains uncommon, and the published surgical literature is dominated by case reports and small series — no randomised data exist.

Registry & practice variation

• There is no implant registry relevant to OALL because osteophytectomy is usually fusion-free; registry data (NJR, AOANJRR, AJRR) only apply if an instrumented fusion is added for instability or a chalk-stick fracture.
• Well-resourced settings: video fluoroscopic swallow study, CT planning, ENT nasendoscopy and awake fiberoptic intubation are standard before surgery.
• Limited-resource settings: diagnosis often rests on plain lateral radiographs and barium swallow; dietary modification and speech-pathology input carry most of the load, with surgery reserved for severe weight loss or aspiration.

• No high-level evidence: the entire surgical literature is case reports and small series; there are no randomised trials or formal guidelines, so recommendations are consensus-based (Harlianto/Verlaan systematic review).
• Fusion vs osteophytectomy alone: most authors avoid routine fusion to spare adjacent-segment disease and operative time, reserving it for instability or iatrogenic disc violation — but the threshold is not standardised.
• Defining "mechanical" dysphagia: dysphagia in elderly DISH patients is often multifactorial (neurological, presbyphagia, reflux). A positive swallow study does not guarantee the osteophyte is the sole cause, and a subset have persistent symptoms after technically successful surgery.
• Predicting recurrence: radiographic regrowth is common yet symptomatic recurrence is rare (~4 percent); no reliable predictor or proven preventive (bisphosphonates, metabolic control) exists.
• Imaging in trauma: whether every ankylosed-spine trauma patient needs MRI in addition to CT remains debated — current data suggest selective use for neurological deficit or suspected disco-ligamentous injury.

Related pages: Diffuse Idiopathic Skeletal Hyperostosis for the systemic disease of which cervical OALL is one expression, and Ossification of the Posterior Longitudinal Ligament for the mirror-image condition that compresses the cord rather than the oesophagus; Ankylosing Spondylitis for the inflammatory disease the Resnick criteria exist to exclude, and which shares the brittle-spine fracture risk with a different distribution; Cervical Myelopathy and Spinal Cord Injury for the neurological consequences of a chalk-stick fracture; and ACDF for the anterior cervical approach and its complication profile.