High Yield Overview

OALL / DISH (Cervical Hyperostosis)

Forestier Disease | Mechanical Dysphagia from Anterior Osteophytes

10-30%Prevalence (over 60yo)

2:1Male:Female

C3-C5Commonest Level

17%Dysphagia Rate

Resnick Criteria (DISH)

Calcification

PatternFlowing calcification along AL of at least 4 contiguous vertebrae

TreatmentDiagnostic

Preservation

PatternPreservation of disc height (unlike degenerative)

TreatmentKey Differentiator

Exclusion

PatternAbsence of sacroiliitis (unlike AS) or facet ankylosis

TreatmentRule out AS

Critical Must-Knows

DISH (Forestier's Disease) is a systemic condition causing 'flowing wax' calcification of the ALL.
OALL is the cervical manifestation, which can mechanically compress the esophagus (Dysphagia) or Airway.
The airway can be 'Difficult' to intubate due to osteophytes preventing visualization.
Surgery (Osteophytectomy) is reserved for severe dysphagia or airway compromise.
Unlike OPLL, OALL does NOT typically cause myelopathy directly.

Examiner's Pearls

"
Look for 'Candle Wax' dripping appearance on X-ray.
"
Ask about 'Aspiration Pneumonia' history in elderly patients with neck stiffness.
"
Differentiation from Ankylosing Spondylitis (AS): DISH spares the SI joints and facets.
"
Surgery should preserve the disc space (Osteophytectomy ONLY) unless instability exists.

Critical Airway Alert

At a Glance

DISH vs Ankylosing Spondylitis

Feature	DISH (Forestier)	Ankylosing Spondylitis (AS)
Age Onset	Old (over 50)	Young (under 40)
SI Joints	Normal (Spared)	Fused (Sacroiliitis)
Disc Space	Preserved	Calcified/Narrowed
HLA-B27	Normal Prevalence	Highly Associated (+)

Mnemonics

Mnemonic

DISHResnick Criteria for DISH

Disc

Disc heights preserved

Involvement

Involvement of 4+ contiguous bodies

Sacroiliac

SI joints spared (No fusion)

Hyperostosis

Hyperostosis is flowing (Candle wax)

Memory Hook:Diagnostic criteria.

Mnemonic

DATESymptoms of OALL

Dysphagia

Difficulty swallowing (Mechanical)

Airway

Stridor, sleep apnea, difficult intubation

Trauma

Hyperextension injury risk

Esophagus

Extrinsic compression

Memory Hook:Clinical presentation.

Mnemonic

HORSESurgical Risks

Hematoma

Retropharyngeal hematoma (Airway!)

Osseo-integration

Regrowth of bone

RLN

Recurrent Laryngeal Nerve palsy

Swallowing

Persistent dysphagia

Esophagus

Perforation (Adherent mucosa)

Memory Hook:Complications of osteophytectomy.

Overview and Epidemiology

Pathophysiology and Anatomy

The Anterior Longitudinal Ligament (ALL)

Broad ligament covering the anterior vertebral bodies.
Prevents hyperextension.
In DISH, it ossifies but spares the annulus fibrosus and nucleus pulposus (unlike Ankylosing Spondylitis).

The Swallowing Mechanism

Phase 1 (Oral): Bolus prep.
Phase 2 (Pharyngeal): Pharynx constricts, Hyoid elevates, Epiglottis inverts.
Phase 3 (Esophageal): Peristalsis. OALL disrupts Phase 2 by physically blocking epiglottic inversion or narrowing the pharyngeal space.

Classification Systems

Resnick Criteria (Gold Standard)

Used to diagnose DISH and distinguish from normal spondylosis.

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

Clinical Assessment

Presentation

Dysphagia: Most common complaining symptom (28% of cervical DISH). "Food sticking".
Globus Sensation: Feeling of a lump in the throat.
Dysphonia: Hoarseness (RLN compression or vocal cord edema).
Stiffness: Decreased cervical ROM.
Dyspnea: Rare, caused by laryngeal edema or massive C3 osteophyte compressing glottis.

Examination

Palpation: Hard, bony mass palpable in the posterior pharynx (beware gag reflex).
Neck: Stiffness, loss of extension.
Neuro: Usually normal (OALL grows OUT, not IN to the canal).

Imaging and Investigations

Workup Protocol

Lateral X-RayScreening

"Flowing Candle Wax" appearance anterior to bodies.
Radiolucent line: Between the ossified ALL and the vertebral body (unossified deep layer).
Check disc heights (spared).

Barium SwallowFunctional

Video Fluoroscopic Swallowing Study (VFSS).
Critical to demonstrate the mechanical cause of dysphagia.
Shows the bolus hitting the osteophyte and spiraling or causing aspiration.

CT and ENTPlanning

CT: Defines bony anatomy for resection.
ENT Nasendoscopy: Mandatory to rule out intrinsic malignancy (cancer) or vocal cord palsy BEFORE surgery.

Management Algorithm

Clinical Algorithm— Dysphagia Management

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Non-Operative Management

First Line Treatment

Dietary Modification: Soft foods, thicken fluids (Speech Pathology involvement).
NSAIDs: Reduce soft tissue inflammation around the osteophytes.
Steroids: Short course for acute flare of dysphagia.
Review: Monitor weight and aspiration signs.

Surgical Technique

Anterior Cervical Osteophytectomy

Goal: Resect the anterior bony mass to decompress the esophagus.
Position: Supine, neck slightly extended (careful! hyperextension can fracture the fused spine). Mayfield head clamp or horseshoe.
Approach: Standard Smith-Robinson (Anterior Cervical).

Step-by-Step:

Incision: Transverse skin incision at the level of the osteophyte (fluoroscopy to confirm).
Dissection: Deep dissection medial to the Carotid sheath and lateral to the Trachea/Esophagus.
Exposure:
- The prevertebral fascia will be tight over the mass.
- Identification of the "valley" between the osteophyte and the disc space is crucial.
Adhesions: The esophagus is often adherent to the tip of the osteophytes due to chronic inflammation. Use a peanut dissector or wet Raytec to gently peel.
Resection:
- Use a high speed Diamond Burr or Leksell Rongeur.
- Resect the "Peaks" (Over the vertebral bodies).
- Be careful at the "Valleys" (Over the discs) not to violate the annulus.
Limits: Resect flush with the anterior margin of the vertebral body. Do not chase lateral osteophytes near the Foramen Transversarium (Vertebral Artery risk).
Disc Sparing: Do not enter the disc space.
Bone Wax: Apply bone wax to the bleeding cancellous surface.
Closure: Deep drain is essential. Close Platysma and Skin.

Fusion?

Generally NOT indicated unless there is pre-existing instability.
Fusion increases adjacent segment disease.

Complications

Complication	Risk Level	Management
Recurrent Laryngeal Nerve Palsy	High	Retraction injury. Observe. Vocal cord medialization if permanent.
Esophageal Perforation	High (Adhesions)	Direct repair + muscle flap. NGT feeding. Antibiotics.
Regrowth	Moderate (years)	Use bone wax. Ensure complete resection.
Hematoma	Moderate	Place drain. Watch airway.

Recurrence

Osteophytes recur in up to 65% of patients over 10 years (as the underlying metabolic driver persists), but symptomatic recurrence is lower (~13%).

Postoperative Care

Airway: Monitor for retropharyngeal hematoma / edema (Stridor).
Feeding: Nasogastric feeding may be needed if esophageal repair done or severe edema.
Swallow Study: Repeat contrast swallow before oral intake if dura/esophagus concerns.

Outcomes and Prognosis

Success Rate: High for dysphagia resolution (89-100%).
Aspiration: May not resolve if the cause was neurological or permanent muscle damage.
QoL: Significant improvement in eating ability.

Evidence Base

Resnick Criteria

Resnick et al • Radiology (1975)

Key Findings:

Defined the radiographic criteria for DISH.
Distinguished it from Ankylosing Spondylitis and Degenerative Disease.
Highlighted the 'flowing' nature of ossification.

Clinical Implication: Gold standard diagnostic criteria.

Surgical Outcomes for OALL

Verlaan et al • Spine (2011)

Key Findings:

Review of 200+ cases of surgical resection for OALL.
Dysphagia improved in 94% of cases.
Complication rate: 1% Esophageal perforation, 2% RLN palsy.
Re-operation for recurrence was rare (4%).

Clinical Implication: Surgery is highly effective for mechanical dysphagia.

Airway Management in DISH

Miyamoto et al • Anesthesia (2009)

Key Findings:

DISH patients have a 4x higher rate of difficult intubation.
Osteophytes prevent alignment of oral-pharyngeal-laryngeal axes.
Recommendation: Awake fiberoptic intubation for C3/4 osteophytes.

Clinical Implication: Never underestimate the airway in OALL.

Osteophytectomy vs Fusion

Yoon et al • Spine J (2016)

Key Findings:

Compared osteophytectomy alone vs osteophytectomy + fusion.
Fusion group had longer OP time and higher cost.
No difference in recurrence or symptom relief.
Conclusion: Fusion not necessary unless instability present.

Clinical Implication: Keep it simple: Remove the bone, leave the disc.

Etiology of DISH

Mader et al • Clin Exp Rheumatol (2013)

Key Findings:

Strong association with Metabolic Syndrome.
High Insulin and IGF-1 levels stimulate osteoblast differentiation.
DISH may be a marker of cardiovascular risk.

Clinical Implication: Treat the whole patient (Diabetes/Obesity management).

Exam Viva Scenarios

Practice these scenarios to excel in your viva examination

VIVA SCENARIOStandard

The Choking Patient

EXAMINER

"75M presents with 6 months of progressive difficulty swallowing solids. He has lost 5kg. He has a history of 'stiff neck'. Lateral X-ray shows massive anterior bone formation C3-C6. What is the diagnosis and workup?"

EXCEPTIONAL ANSWER

The X-ray appearance suggests **Diffuse Idiopathic Skeletal Hyperostosis (DISH)** or OALL. **Workup**: 1. **Rule out Cancer**: This is an elderly male with weight loss. He needs an **ENT review** and **Nasendoscopy** to exclude an intrinsic esophageal/pharyngeal tumour. 2. **Confirm Mechanics**: **Barium Swallow (Video Fluoroscopy)** to prove the osteophyte is the cause. 3. **CT Scan**: To map the anatomy for potential surgery. **Management**: - If investigations confirm mechanical obstruction: - Trial of soft diet and NSAIDs. - If fails/weight loss continues → **Anterior Osteophytectomy**.

KEY POINTS TO SCORE

Cancer is the most common cause of dysphagia in elderly - rule it out!

X-ray is suggestive, but function (Swallow) is diagnostic

Surgery is effective but has risks (Esophagus/RLN)

COMMON TRAPS

✗Attributing weight loss solely to DISH without excluding cancer

✗Jumping to surgery without a Swallow study

VIVA SCENARIOStandard

Intubation Difficulty

EXAMINER

"You are called to ED for a DISH patient who has fallen and hit his head. GCS 8. The ED registrar cannot intubate. Why?"

EXCEPTIONAL ANSWER

**Mechanism**: Massive anterior cervical osteophytes (OALL) physically displace the pharynx anteriorly and prevent the laryngoscope blade from displacing the tongue base/epiglottis. **Action**: 1. **Do NOT force**: Trauma to the friable swelling/osteophytes can cause bleeding/edema and lose the airway completely. 2. **Plan B**: Video Laryngoscope may help. 3. **Gold Standard**: **Fiberoptic Intubation** (if spontaneous breathing) or **Surgical Airway** (Cricothyroidotomy) if can't intubate/can't ventilate. **Secondary Issue**: The fall may have caused a fracture through the fused spine (**Chalk Stick Fracture**). Immobilization is critical.

KEY POINTS TO SCORE

Difficult Airway algorithm

Chalk Stick Fracture risk

Avoid hyperextension during intubation

COMMON TRAPS

✗Repeated attempts at direct laryngoscopy

✗Extending the neck in a potential fracture

VIVA SCENARIOStandard

Intra-op Complication

EXAMINER

"During osteophytectomy, you notice a Bubble in the wound field. What has happened and what do you do?"

EXCEPTIONAL ANSWER

This indicates either an **Esophageal Perforation** (air leaking) or Tracheal injury (less likely). **Action**: 1. **Stop**: Identify the source. 2. **Test**: Fill the wound with saline and ask anaesthetist to insufflate air (or inject Methylene Blue via NGT). 3. **Repair**: - Small (less than 1cm): Primary closure in layers + **Sternocleidomastoid Muscle Flap** reinforcement. - Large: Consult ENT/Upper GI surgeon. 4. **Post-op**: NGT feeding for 7-10 days. Antibiotics. Contrast swallow before oral intake.

KEY POINTS TO SCORE

Recognition (Bubbles/Blue dye)

Watertight repair

Muscle flap reinforcement

Prolonged NGT feeding

COMMON TRAPS

✗Ignoring the bubble

✗Closing without a flap

MCQ Practice Points

Diagnosis

Q: Which feature distinguishes DISH from Ankylosing Spondylitis? A: Preservation of SI joints and Facet joints (No ankylosis).

Anatomy

Q: What structure ossifies in DISH? A: Anterior Longitudinal Ligament (ALL).

Complication

Q: Post-operative hoarseness after osteophytectomy is most likely due to? A: Recurrent Laryngeal Nerve (RLN) neurapraxia (from retraction).

Association

Q: DISH is strongly associated with which metabolic disorder? A: Type 2 Diabetes Mellitus / Obesity.

Management

Q: When is fusion indicated in OALL surgery? A: Only if instability is present. (E.g. fracture or iatrogenic disc violation). Routine fusion is unnecessary.

Australian Context

Epidemiology

High prevalence in elderly Australian population (often incidental on trauma CTs).

WorkCover

Beware of assuming dysphagia is work-related, BUT a minor work injury (whiplash) can exacerbate symptoms in a DISH patient.

Exam Day Cheat Sheet

OALL / DISH Summary

High-Yield Exam Summary

Key Concepts

•Flowing Anterolateral Ossification
•Disc Height Preserved
•SI Joints Normal
•Dysphagia over Dyspnea

Criteria (Resnick)

•4+ Contiguous bodies
•Discs spared
•No Facet/SI fusion
•Flowing Candles

Surgery

•Indication: Severe Dysphagia/Wt Loss
•Procedure: Anterior Osteophytectomy
•Protect Esophagus!
•No Fusion usually

Risks

•Esophageal Perforation
•RLN Palsy
•Recurrence
•Hematoma (Airway)

Image Manifest

[3-preoperative-computed-tomography-ct-a-ct-of-the-ce.png]: Sagittal CT showing OALL and disc preservation
- [5-preoperative-esophagram-revealed-extrinsic-compres.png]: Barium swallow showing esophageal compression

Feature

DISH (Forestier)

Ankylosing Spondylitis (AS)

Age Onset

Old (over 50)

Young (under 40)

SI Joints

Normal (Spared)

Fused (Sacroiliitis)

Disc Space

Preserved

Calcified/Narrowed

HLA-B27

Normal Prevalence

Highly Associated (+)

Complication

Risk Level

Management

Recurrent Laryngeal Nerve Palsy

High

Retraction injury. Observe. Vocal cord medialization if permanent.

Esophageal Perforation

High (Adhesions)

Direct repair + muscle flap. NGT feeding. Antibiotics.

Regrowth

Moderate (years)

Use bone wax. Ensure complete resection.

Hematoma

Moderate

Place drain. Watch airway.

Resnick Criteria

Resnick et al • Radiology (1975)

Key Findings:

Defined the radiographic criteria for DISH.
Distinguished it from Ankylosing Spondylitis and Degenerative Disease.
Highlighted the 'flowing' nature of ossification.

Clinical Implication: Gold standard diagnostic criteria.

Surgical Outcomes for OALL

Verlaan et al • Spine (2011)

Key Findings:

Review of 200+ cases of surgical resection for OALL.
Dysphagia improved in 94% of cases.
Complication rate: 1% Esophageal perforation, 2% RLN palsy.
Re-operation for recurrence was rare (4%).

Clinical Implication: Surgery is highly effective for mechanical dysphagia.

Airway Management in DISH

Miyamoto et al • Anesthesia (2009)

Key Findings:

DISH patients have a 4x higher rate of difficult intubation.
Osteophytes prevent alignment of oral-pharyngeal-laryngeal axes.
Recommendation: Awake fiberoptic intubation for C3/4 osteophytes.

Clinical Implication: Never underestimate the airway in OALL.

Osteophytectomy vs Fusion

Yoon et al • Spine J (2016)

Key Findings:

Compared osteophytectomy alone vs osteophytectomy + fusion.
Fusion group had longer OP time and higher cost.
No difference in recurrence or symptom relief.
Conclusion: Fusion not necessary unless instability present.

Clinical Implication: Keep it simple: Remove the bone, leave the disc.

Etiology of DISH

Mader et al • Clin Exp Rheumatol (2013)

Key Findings:

Strong association with Metabolic Syndrome.
High Insulin and IGF-1 levels stimulate osteoblast differentiation.
DISH may be a marker of cardiovascular risk.

Clinical Implication: Treat the whole patient (Diabetes/Obesity management).