# Clinical Cases: Pain Medicine ## Case 1: Complex Regional Pain Syndrome ### Patient Presentation **Demographics:** 34-year-old female software engineer **Chief Complaint:** "My left hand and wrist have been burning and swollen for 4 months after a simple fracture — the pain is unbearable and getting worse." **History of Present Illness:** Ms. E.N. presents to the pain medicine clinic with a 4-month history of progressive, debilitating left upper extremity pain following a distal radius fracture sustained in a cycling accident. The fracture was non-displaced and managed conservatively with a short arm cast for 6 weeks. Upon cast removal, she noted immediate pain disproportionate to the injury, describing it as a constant burning, aching sensation rated 8-9/10 on the numeric pain scale. The pain has progressively worsened and now extends from the fingertips to the mid-forearm. She reports that the affected hand has changed color, alternating between deep red/purple and pale/mottled, and that the skin temperature fluctuates dramatically — sometimes the hand feels burning hot, other times ice cold. She has noticed significant swelling in the dorsum of the hand and fingers. The skin has become shiny, thin, and hypersensitive; she cannot tolerate clothing touching the hand, water running over it, or even air currents from a fan (severe allodynia). She has stopped wearing her engagement ring due to edema and hypersensitivity. Functionally, she is unable to type, grip objects, or use her left hand for activities of daily living. She has been on medical leave from work for 3 months. She reports sleep disruption (averaging 3 hours per night due to pain), depressed mood, anxiety, and social withdrawal. She has been referred by her orthopedic surgeon after failing 6 weeks of hand therapy and oral analgesics. **Past Medical History:** - Anxiety disorder (generalized) - Migraine with aura (2-3 per month) - No prior chronic pain conditions **Medications:** - Gabapentin 300 mg TID (started 6 weeks ago, minimal benefit) - Oxycodone 5 mg Q6H PRN (taking regularly, reports 20% pain relief) - Sertraline 50 mg daily - Sumatriptan 100 mg PRN for migraines **Social History:** - Non-smoker - Rare alcohol use - Lives with fiancé; wedding planned in 6 months (considering postponement) - Previously very active: rock climbing, cycling, yoga - On medical leave from software engineering position **Family History:** - Mother: fibromyalgia, depression - Maternal aunt: CRPS following knee surgery (3-year course) - Father: healthy ### Physical Examination - **Vital Signs:** BP 138/86 mmHg (anxiety/pain), HR 96 bpm, RR 18, SpO2 99%, Temp 36.8°C - **Left upper extremity:** - Inspection: Dorsal hand and wrist edematous; skin erythematous with violaceous mottling; skin appears shiny, thin, and atrophic with loss of normal skin creases; excessive hair growth on dorsum of hand compared to right; nail changes — ridging and brittleness of all fingernails - Temperature: Infrared thermometry reveals 3.2°C asymmetry (left hand 31.1°C vs. right hand 34.3°C — left hand cooler) - Sweating: Increased sudomotor activity on left palm compared to right - Allodynia: Severe mechanical allodynia — light brush stroke (cotton wisp) over dorsum of hand elicits 9/10 pain; thermal allodynia present to both warm and cool stimuli - Hyperalgesia: Pinprick hyperalgesia extending from fingertips to mid-forearm (non-dermatomal distribution) - ROM: Active wrist flexion 15° (normal 80°), extension 10° (normal 70°); finger flexion severely limited; unable to make a fist - Motor: Grip strength not testable due to pain; difficulty initiating finger movements (motor neglect-like pattern); intermittent dystonic posturing of fingers noted - Edema: 2+ pitting edema dorsum of hand; circumferential measurement 2.5 cm greater than right - **Right upper extremity:** Normal examination throughout - **Psychological assessment:** Pain Catastrophizing Scale: 38/52 (high); Tampa Scale of Kinesiophobia: 44/68 (moderate-high fear of movement) ### Workup and Results **Laboratory Studies:** | Test | Result | Reference Range | |------|--------|-----------------| | CBC | WNL | - | | ESR | 12 mm/hr | 0-20 mm/hr | | CRP | 0.8 mg/L | <3.0 mg/L | | ANA | Negative | Negative | | RF | Negative | <14 IU/mL | | Uric acid | 4.2 mg/dL | 2.4-6.0 mg/dL | | HbA1c | 5.1% | <5.7% | | Vitamin D | 28 ng/mL | 30-100 ng/mL | **Imaging/Additional Studies:** - **Triple-phase bone scan:** Increased uptake in all three phases in the left hand and wrist — diffuse periarticular uptake in the delayed phase involving MCP, PIP, and DIP joints and distal radius/ulna (highly suggestive of CRPS) - **Plain radiographs (left hand/wrist):** Healed distal radius fracture in anatomic alignment; diffuse patchy osteopenia of the carpals, metacarpals, and phalanges; periarticular osteoporosis (Sudeck atrophy) - **MRI left hand/wrist:** Diffuse bone marrow edema in carpals and distal radius; soft tissue edema; thickening of palmar fascia; no evidence of fracture non-union or hardware complication; no mass or infection - **Quantitative sudomotor axon reflex test (QSART):** Asymmetric sweat output — 3x increase on left forearm compared to right - **Autonomic testing:** Resting skin temperature asymmetry confirmed (>1°C); laser Doppler flowmetry shows decreased blood flow in affected hand ### Clinical Image ![Clinical features of Complex Regional Pain Syndrome](case_01_image.jpg) *Illustration depicting the clinical features of CRPS Type I, showing the affected hand with edema, color changes, trophic skin changes, and a comparison of sympathetic nervous system dysregulation pathways. Source: Educational illustration.* ### Diagnosis **Complex Regional Pain Syndrome Type I (Reflex Sympathetic Dystrophy), Left Upper Extremity — Warm-to-Cold Transition Phase** **Key Diagnostic Criteria (Budapest Criteria — all 4 met):** 1. Continuing pain disproportionate to the inciting event (distal radius fracture) 2. At least one sign in 3 or more categories: - Sensory: allodynia (mechanical and thermal), hyperalgesia - Vasomotor: temperature asymmetry (>1°C), skin color changes - Sudomotor/edema: edema, sweating asymmetry - Motor/trophic: decreased ROM, motor dysfunction (weakness, dystonia), trophic changes (skin, nail, hair) 3. At least one symptom in all 4 categories (reported by patient) 4. No other diagnosis better explains the signs and symptoms ### Treatment Plan 1. **Interventional pain management:** - Stellate ganglion block (sympathetic block) — diagnostic and therapeutic; series of 3 blocks at weekly intervals with local anesthetic (bupivacaine 0.25%) - If sympathetically maintained pain confirmed: consider pulsed radiofrequency of stellate ganglion or spinal cord stimulation trial if blocks provide temporary but non-sustained relief 2. **Pharmacological optimization:** - Increase gabapentin to 600 mg TID (titrate to 900 mg TID as tolerated) - Add low-dose naltrexone 4.5 mg nightly (emerging evidence for neuroinflammation) - Topical compounded cream: ketamine 10% / gabapentin 6% / clonidine 0.2% — applied to affected area TID - Taper oxycodone over 4 weeks (opioids may worsen CRPS through neuroinflammatory mechanisms and have limited evidence) - Bisphosphonate: IV pamidronate 60 mg single infusion (evidence for CRPS-associated bone pain and osteopenia) - Vitamin D3 2,000 IU daily 3. **Rehabilitation (critical component):** - Graded motor imagery program: left/right discrimination training → imagined movements → mirror therapy (10 min, 3x daily) - Pain exposure physical therapy (PEPT) with desensitization hierarchy - Occupational therapy for functional restoration - Aquatic therapy (warm water pool) for gentle ROM and desensitization 4. **Psychological support:** - Cognitive behavioral therapy for chronic pain (pain catastrophizing reduction) - Acceptance and Commitment Therapy (ACT) for pain-related anxiety - Sleep hygiene optimization; consider trazodone 50 mg for sleep 5. **Follow-up:** Re-evaluate at 4 weeks; if inadequate response to sympathetic blocks, consider spinal cord stimulation trial (dorsal column or dorsal root ganglion stimulation) ### Key Learning Points - CRPS is diagnosed clinically using the Budapest Criteria; no single laboratory or imaging test is diagnostic, but triple-phase bone scan and MRI support the diagnosis. Normal inflammatory markers do not exclude CRPS - The pathophysiology involves peripheral and central sensitization, neurogenic inflammation, sympathetic-afferent coupling, and maladaptive cortical reorganization — it is not primarily a psychological disorder - Early aggressive treatment within the first 6-12 months offers the best prognosis; the condition becomes increasingly refractory with chronicity due to progressive central sensitization - Mirror therapy and graded motor imagery are evidence-based rehabilitation strategies that target cortical body representation changes; they should be initiated early and performed consistently - Opioids have limited efficacy in CRPS and may worsen outcomes through glial activation and neuroinflammation; a multimodal approach combining interventional, pharmacological, rehabilitative, and psychological strategies is essential --- ## Case 2: Chronic Low Back Pain with Central Sensitization ### Patient Presentation **Demographics:** 48-year-old male warehouse supervisor **Chief Complaint:** "My back has hurt every day for 5 years and now the pain is spreading everywhere — nothing works anymore." **History of Present Illness:** Mr. D.W. presents to the multidisciplinary pain center with a 5-year history of chronic low back pain that has progressively worsened and expanded in distribution. The pain originated after a workplace lifting injury in which he felt a "pop" while moving a 30 kg box. Initial imaging showed a L4-5 disc herniation with left L5 radiculopathy, which was managed with epidural steroid injections and physical therapy with moderate relief over the first 18 months. Over the past 3 years, the pain has changed in character from well-localized left-sided low back and leg pain to a diffuse, bilateral low back, buttock, and lower extremity pain that he describes as burning, aching, and "electrical." He has developed widespread tenderness — reporting that his thighs, calves, and even upper back now hurt. He notes that activities that previously were not painful (sitting for 20 minutes, riding in a car, light walking) now provoke severe pain flares lasting 2-3 days. Even emotional stress and poor sleep dramatically worsen his pain. He has undergone two L4-5 epidural steroid injections (last one 2 years ago, minimal benefit), bilateral medial branch blocks at L3-5 (equivocal response), and a trial of physical therapy (4 courses, unable to progress due to pain flares). He was prescribed escalating doses of opioids by his primary care physician and currently takes oxycodone 20 mg QID with minimal analgesic efficacy. He has gained 18 kg since the injury and is largely sedentary. **Past Medical History:** - L4-5 disc herniation (5 years ago, managed non-operatively) - Major depressive disorder (diagnosed 3 years ago, coinciding with chronic pain) - Obstructive sleep apnea (diagnosed 1 year ago, non-adherent with CPAP) - Obesity - Pre-hypertension **Medications:** - Oxycodone 20 mg QID (80 mg/day = 120 MME/day) - Duloxetine 60 mg daily - Cyclobenzaprine 10 mg THS (at bedtime) - Omeprazole 20 mg daily - Ibuprofen 800 mg TID (intermittent) **Social History:** - Former smoker (quit 2 years ago, 20 pack-year history) - No alcohol (quit when started opioids) - Married, 3 children; reports significant marital strain due to disability - On long-term disability from work; workers' compensation claim settled - Spends most of day in recliner watching television - Previously active: recreational basketball, home renovation projects **Family History:** - Mother: chronic pain (fibromyalgia), opioid use disorder - Father: alcohol use disorder, depression - Brother: chronic low back pain ### Physical Examination - **Vital Signs:** BP 142/90 mmHg, HR 78 bpm, RR 14, SpO2 94% on room air, Temp 36.7°C, BMI 36.2 kg/m² - **General:** Obese male in mild distress, moves slowly and guardedly; uses cane for ambulation (no prescription for assistive device) - **Spine:** Lumbar paraspinal hypertonicity bilaterally; tenderness to palpation diffusely across lumbar, thoracolumbar, and sacroiliac regions; limited flexion (finger-to-floor distance 45 cm); Waddell signs: 3/5 positive (superficial tenderness, overreaction, regional disturbance) - **Neurological:** Straight leg raise negative bilaterally; motor strength 5/5 bilateral lower extremities (give-way weakness pattern noted but full strength when distracted); sensation intact to light touch throughout; reflexes 2+ and symmetric; no clonus; Babinski downgoing bilaterally - **Central sensitization signs:** - Widespread allodynia: mechanical allodynia to light brush over bilateral thighs, calves, and upper back (non-dermatomal) - Temporal summation: repeated pinprick at same location on forearm produces progressively increasing pain (wind-up) - Expanded receptive fields: pain from lumbar region referred to bilateral lower extremities and upper back without anatomic correlation - **Psychological screening:** PHQ-9: 18 (moderately severe depression); PCS: 42/52 (very high catastrophizing); FABQ-W: 55 (high fear-avoidance); PHQ-15: 14 (high somatic symptom burden); Central Sensitization Inventory (CSI): 58/100 (central sensitization present, score >40) ### Workup and Results **Laboratory Studies:** | Test | Result | Reference Range | |------|--------|-----------------| | CBC | WNL | - | | ESR | 18 mm/hr | 0-22 mm/hr | | CRP | 4.1 mg/L | <3.0 mg/L | | HbA1c | 6.1% | <5.7% | | Testosterone (total) | 185 ng/dL | 264-916 ng/dL | | Vitamin D (25-OH) | 14 ng/mL | 30-100 ng/mL | | Urine drug screen | Positive: oxycodone, oxymorphone (metabolite) | Consistent with prescribed | **Imaging/Additional Studies:** - **MRI lumbar spine (current):** L4-5 disc desiccation with mild diffuse bulge; no significant disc herniation; no neural foraminal stenosis; no central canal stenosis; mild facet arthropathy L4-5 and L5-S1; Modic Type II endplate changes at L4-5 - **Quantitative sensory testing (QST):** Decreased pressure pain thresholds at multiple remote sites (bilateral trapezius, bilateral tibialis anterior); enhanced temporal summation of pain; impaired conditioned pain modulation (CPM deficit — descending inhibitory failure) - **Functional capacity evaluation:** Self-limited performance; biomechanical inconsistencies noted; estimated functional capacity: sedentary work with position changes - **Polysomnography review:** AHI 28/hr (moderate OSA); minimum SpO2 82%; sleep efficiency 58% ### Clinical Image ![Central sensitization mechanisms in chronic pain](case_02_image.jpg) *Diagram illustrating the neurophysiology of central sensitization, showing peripheral nociceptor input, dorsal horn wind-up, loss of descending inhibition, and cortical reorganization leading to widespread pain amplification. Source: Educational illustration.* ### Diagnosis **Chronic Low Back Pain with Nociplastic Pain (Central Sensitization Syndrome), Opioid-Induced Hyperalgesia, and Comorbid Major Depression** **Key Diagnostic Criteria:** - Pain disproportionate to identifiable structural pathology (mild disc changes on current MRI without nerve compression) - Pain spreading beyond original anatomic region to non-dermatomal distribution - Central Sensitization Inventory score >40 (58/100) - QST demonstrating: reduced pressure pain thresholds at remote sites, enhanced temporal summation, impaired conditioned pain modulation - Allodynia and hyperalgesia in areas remote from the lumbar spine - Features consistent with opioid-induced hyperalgesia: progressive dose escalation with worsening, diffuse pain; expanding pain distribution correlating with opioid dose increases - Significant psychosocial contributors: depression, catastrophizing, fear-avoidance, deconditioning, disability mindset ### Treatment Plan 1. **Opioid taper (critical first step):** - Structured taper of oxycodone: reduce by 10% every 2 weeks (target: off opioids in 5-6 months) - Bridge with buprenorphine transdermal patch if needed (partial agonist — less hyperalgesia risk) - Address opioid-induced endocrinopathy: testosterone replacement if levels remain low after taper 2. **Central sensitization-targeted pharmacotherapy:** - Optimize duloxetine: increase to 90 mg then 120 mg daily (dual SNRI effect for pain and depression) - Add pregabalin 75 mg BID, titrate to 150 mg BID (calcium channel modulation, reduces central sensitization) - Discontinue cyclobenzaprine (limited long-term evidence, sedation compounding OSA) - Low-dose naltrexone 4.5 mg nightly (glial modulator, emerging evidence for nociplastic pain) - Vitamin D3 5,000 IU daily for 8 weeks then 2,000 IU maintenance 3. **Functional restoration program (intensive interdisciplinary):** - 4-week intensive program (4 hours/day, 5 days/week): graded exercise therapy with pain neuroscience education - Quota-based exercise progression (not pain-contingent): walking, swimming, core stabilization - Goal: progressive return to function regardless of pain level 4. **Pain neuroscience education (PNE):** - Reconceptualize pain: pain ≠ damage; explain central sensitization in patient-accessible terms - Address threat appraisal and pain catastrophizing - Shift from biomedical to biopsychosocial model of pain 5. **Psychological interventions:** - CBT for chronic pain: targeting catastrophizing (PCS goal <20), fear-avoidance beliefs, behavioral activation - Mindfulness-based stress reduction (MBSR) program - Acceptance and Commitment Therapy for values-based functional engagement 6. **Sleep optimization:** - Mandatory CPAP adherence for OSA (untreated OSA worsens pain sensitization) - CBT for insomnia (CBT-I) 7. **Follow-up:** Monthly during opioid taper; validated outcome measures (PCS, CSI, PHQ-9, PROMIS Pain Interference) at each visit ### Key Learning Points - Central sensitization (now termed "nociplastic pain" per IASP taxonomy) represents a third mechanism of pain distinct from nociceptive and neuropathic pain; it is characterized by augmented CNS pain processing with allodynia, hyperalgesia, expanded receptive fields, and pain spreading beyond the original injury site - The Central Sensitization Inventory (CSI) is a validated screening tool; quantitative sensory testing (QST) provides objective evidence of altered pain processing including impaired conditioned pain modulation (a measure of descending inhibitory pathway function) - Opioid-induced hyperalgesia is a paradoxical increase in pain sensitivity caused by chronic opioid use; it is neurobiologically distinct from tolerance and should be suspected when pain worsens or spreads despite dose escalation - Pain neuroscience education is an evidence-based intervention that reduces pain catastrophizing and fear-avoidance by reconceptualizing pain as a product of neural sensitization rather than ongoing tissue damage - Interdisciplinary pain rehabilitation programs combining graded exercise, PNE, and cognitive-behavioral therapy demonstrate superior outcomes to unimodal treatments for chronic pain with central sensitization --- ## Case 3: Cancer Pain Management with Multimodal Approach ### Patient Presentation **Demographics:** 62-year-old male retired firefighter **Chief Complaint:** "The pain in my back and ribs is getting worse despite the morphine — I can barely get out of bed now." **History of Present Illness:** Mr. R.C. is referred to the palliative pain service from oncology for escalating pain in the context of metastatic non-small cell lung cancer (adenocarcinoma, EGFR-negative, PD-L1 50%, stage IV). He was diagnosed 14 months ago after presenting with persistent cough and hemoptysis. Initial staging revealed a 4.2 cm right upper lobe primary with mediastinal lymphadenopathy, T3 rib involvement (right 4th and 5th ribs), and osseous metastases to T8, T11, L2, and the right ilium. He has received pembrolizumab with carboplatin/pemetrexed (4 cycles), with partial response in the primary but progression of osseous disease. His pain is multifocal: (1) constant, deep, aching mid-thoracic back pain rated 7/10 centered at T8 and T11, worsened by movement and position changes (somatic nociceptive — bone metastases); (2) sharp, lancinating right chest wall pain at the 4th-5th ribs rated 8/10, provoked by breathing, coughing, and truncal rotation (mixed nociceptive/neuropathic — rib metastases with intercostal nerve involvement); (3) intermittent burning, shooting pain radiating from the mid-back into the bilateral lower extremities, rated 6/10 (neuropathic — epidural extension at T11 with nerve root compression). He reports 4-5 breakthrough pain episodes daily, each lasting 15-45 minutes, often triggered by movement. His current oral morphine regimen provides approximately 40% pain relief. He has lost 8 kg in the past 3 months, has poor appetite, and his functional status has declined from ECOG 1 to ECOG 3 over 2 months. **Past Medical History:** - Non-small cell lung cancer (adenocarcinoma), stage IV with osseous metastases (diagnosed 14 months ago) - COPD (moderate, FEV1 55% predicted) - Occupational exposures: 30 years of firefighting with smoke, asbestos, diesel exhaust, PFAS exposure - Hypertension - Remote history of alcohol use disorder (sober 15 years) **Medications:** - Morphine sulfate extended-release 60 mg BID (120 mg/day) - Morphine sulfate immediate-release 15 mg Q4H PRN breakthrough (using 4-5 doses/day) - Dexamethasone 4 mg BID - Pembrolizumab 200 mg IV Q3 weeks (ongoing) - Tiotropium 18 mcg inhaled daily - Lisinopril 10 mg daily - Ondansetron 4 mg Q8H PRN nausea - Docusate/senna BID - Omeprazole 20 mg daily **Social History:** - Former smoker: 40 pack-year history (quit 5 years ago) - Alcohol: sober 15 years (AA member) - Married, 4 adult children (all local and supportive) - Retired firefighter (30 years of service); strong social network through fire department - Has advance directive in place; full code status currently but "open to discussing" hospice **Family History:** - Father: lung cancer (died age 68, smoker) - Mother: breast cancer (survived, died age 82 of stroke) ### Physical Examination - **Vital Signs:** BP 108/68 mmHg, HR 92 bpm, RR 22, SpO2 91% on room air, Temp 36.9°C, BMI 22.1 kg/m² (down from 26.3) - **General:** Cachectic-appearing, chronically ill male; grimaces with position changes; moderately sedated (Richmond Agitation-Sedation Scale -1) - **Pulmonary:** Decreased breath sounds right upper lobe; scattered rhonchi bilaterally; tenderness to palpation over right 4th-5th ribs with palpable mass - **Spine:** Point tenderness over T8 and T11 spinous processes; midline and paraspinal tenderness at T11-L2; no gibbus deformity - **Neurological:** - Lower extremities: bilateral hip flexor weakness 4/5; knee extension 4+/5 bilaterally; ankle dorsiflexion 5/5 bilaterally - Sensory: diminished pinprick sensation in bilateral T10-L1 dermatomes; burning dysesthesia with light touch over right T4-T5 dermatomes - Reflexes: patellar reflexes 3+ bilaterally (hyperreflexic); no clonus; Babinski equivocal on left - Allodynia in right T4-T5 intercostal distribution - **Abdomen:** Soft, mildly distended, decreased bowel sounds (opioid-related constipation) - **Functional assessment:** ECOG 3; Palliative Performance Scale 40%; unable to ambulate independently; requires assistance with transfers ### Workup and Results **Laboratory Studies:** | Test | Result | Reference Range | |------|--------|-----------------| | Hemoglobin | 10.2 g/dL | 13.5-17.5 g/dL | | Calcium (corrected) | 11.8 mg/dL | 8.5-10.5 mg/dL | | Alkaline phosphatase | 342 U/L | 44-147 U/L | | Creatinine | 1.4 mg/dL | 0.7-1.3 mg/dL | | Albumin | 2.8 g/dL | 3.5-5.0 g/dL | | LDH | 485 U/L | 140-280 U/L | | PSA | 1.2 ng/mL | <4.0 ng/mL | | 25-OH Vitamin D | 12 ng/mL | 30-100 ng/mL | **Imaging/Additional Studies:** - **CT chest/abdomen/pelvis:** Stable right upper lobe mass (3.8 cm, decreased from 4.2 cm); new pathologic compression fracture T11 with 40% height loss; progressive lytic lesions T8, L2, right ilium; epidural soft tissue component at T11 causing moderate spinal canal narrowing but no frank cord compression - **MRI thoracolumbar spine:** T11 pathologic fracture with retropulsion of fragment into ventral thecal sac; epidural tumor extension causing 50% canal compromise at T11; T8 and L2 vertebral body metastases without canal stenosis; no definitive cord signal abnormality on T2-weighted sequences - **Bone scan:** Multiple areas of increased uptake: T8, T11, L2, right ilium, bilateral 4th-5th ribs; no new metastatic sites compared to prior scan - **Edmonton Symptom Assessment Scale:** Pain 8/10, fatigue 8/10, nausea 4/10, depression 5/10, anxiety 6/10, drowsiness 6/10, appetite 2/10, wellbeing 3/10, constipation 7/10 ### Clinical Image ![Multimodal cancer pain management approach](case_03_image.jpg) *Illustration depicting the WHO analgesic ladder modified for cancer pain, integrated with interventional and multimodal strategies for bone metastasis pain management. Source: Educational illustration.* ### Diagnosis **Cancer-Related Pain Syndrome, Mixed Mechanism: Somatic Nociceptive (Bone Metastases), Neuropathic (Intercostal and Epidural Nerve Compression), with Incident/Breakthrough Pain — in the Setting of Metastatic NSCLC with Impending Spinal Cord Compression and Malignant Hypercalcemia** **Key Diagnostic Criteria:** - Multifocal pain with identifiable structural causes on imaging (bone metastases, rib involvement, epidural extension) - Three distinct pain mechanisms identified: somatic nociceptive (bone), neuropathic (nerve compression/invasion), and movement-evoked (incident) pain - Epidural disease at T11 with early neurological signs (hyperreflexia, mild weakness) indicating impending cord compression — oncological emergency - Hypercalcemia of malignancy (corrected calcium 11.8 mg/dL) contributing to symptom burden - Pain inadequately controlled on 120 mg oral morphine equivalent daily with breakthrough dosing ### Treatment Plan 1. **Urgent interventions:** - **Hypercalcemia:** IV normal saline 1L bolus then 200 mL/hr; zoledronic acid 4 mg IV over 15 minutes; recheck calcium at 24 and 48 hours - **Impending cord compression:** Increase dexamethasone to 10 mg IV Q6H (24-48 hours) then taper; urgent radiation oncology consultation for T11 (conventional external beam RT 30 Gy in 10 fractions or stereotactic body RT 24 Gy in 2 fractions); neurosurgery consultation for consideration of T11 decompression and stabilization if surgical candidate 2. **Opioid optimization:** - Rotate from morphine to hydromorphone (incomplete cross-tolerance advantage; better in renal impairment with Cr 1.4) - Calculate equianalgesic dose: morphine 120 mg oral/day + 60-75 mg breakthrough = ~180-195 mg/day → hydromorphone oral ~36-39 mg/day → reduce by 25% for rotation = ~28-30 mg/day → hydromorphone ER 8 mg TID with hydromorphone IR 4 mg Q3H PRN - Rapid-onset fentanyl (buccal tablet 200 mcg) for breakthrough episodes with fast onset needed 3. **Neuropathic pain adjuvants:** - Add pregabalin 75 mg BID, titrate to 150 mg BID over 2 weeks (target intercostal and radicular neuropathic pain) - Consider lidocaine 5% patch over right chest wall (topical for intercostal allodynia) - If neuropathic component refractory: consider ketamine infusion (sub-anesthetic, 0.1-0.3 mg/kg/hr for 24-48 hours) 4. **Interventional pain management:** - Right intercostal nerve block (T4-T5) with bupivacaine and dexamethasone for chest wall pain - If sustained benefit needed: intercostal neurolysis with phenol or cryoablation - Consider intrathecal drug delivery system (IDDS) if pain continues to escalate (intrathecal morphine + bupivacaine ± ziconotide); patient on >200 MME/day is appropriate candidate per PACC guidelines 5. **Bone-targeted therapy:** - Continue zoledronic acid 4 mg IV Q4 weeks (both hypercalcemia and skeletal events) - Denosumab 120 mg SC Q4 weeks as alternative if renal function declines - Palliative radiation to T8 and right ilium if pain remains refractory - Radium-223 or samarium-153 consideration deferred (non-prostate cancer, limited data) 6. **Supportive and palliative care:** - Aggressive bowel regimen: methylnaltrexone 12 mg SC every other day (opioid-induced constipation refractory to oral laxatives) - Nutritional support: megestrol acetate 400 mg daily or consider olanzapine 2.5 mg for appetite - Vitamin D3 50,000 IU weekly x 8 weeks then 2,000 IU daily - Physical therapy for mobility preservation and fall prevention - Palliative care team co-management; goals of care discussion; hospice eligibility review 7. **Follow-up:** 48-hour reassessment of calcium and neurological status; weekly pain reassessments during radiation course; ESAS tracking at every visit ### Key Learning Points - Cancer pain is frequently mixed-mechanism, involving nociceptive (somatic and visceral), neuropathic, and nociplastic components; each mechanism requires targeted pharmacotherapy for optimal control — a single-agent approach is rarely sufficient - Opioid rotation is indicated when dose-limiting side effects occur or when analgesic efficacy plateaus; the equianalgesic dose calculation must include a 25-50% reduction for incomplete cross-tolerance, with careful titration - Impending spinal cord compression is an oncological emergency; the combination of epidural disease, hyperreflexia, and emerging weakness mandates urgent high-dose corticosteroids and radiation oncology consultation within 24 hours - Interventional techniques (nerve blocks, neuraxial analgesia, intrathecal pumps) should be considered early in cancer pain management, not as a last resort; IDDS can provide superior analgesia with lower systemic opioid side effects - Hypercalcemia of malignancy occurs in up to 30% of advanced cancers and contributes to pain, confusion, constipation, and fatigue; IV hydration and bisphosphonates are first-line treatment and may independently improve pain control