What is the best course of treatment for an elderly male with left lower back pain, intolerance to sitting or standing, and hypersensitivity to touch on the lower spine, with a negative Magnetic Resonance Imaging (MRI) scan?

Suspect Complex Regional Pain Syndrome (CRPS) or Neuropathic Pain and Initiate Targeted Treatment

This elderly male with severe left lower back pain, inability to sit still, extreme hypersensitivity to touch (allodynia), and negative MRI most likely has a neuropathic pain syndrome, potentially Complex Regional Pain Syndrome (CRPS) Type II or central sensitization, requiring immediate neuropathic pain management rather than further structural imaging.

Clinical Reasoning for This Presentation

The constellation of symptoms—severe pain, motor restlessness (cannot sit still), and marked allodynia (cannot tolerate touch to the spine)—with negative MRI strongly suggests a neuropathic or centralized pain process rather than structural pathology 1, 2. When MRI is negative in the setting of severe symptoms with hypersensitivity, the focus must shift from searching for structural lesions to treating the pain syndrome itself 3, 4.

Key Diagnostic Considerations

• Allodynia (hypersensitivity to touch) is a hallmark of neuropathic pain and central sensitization, not typical of mechanical or structural spine pathology 5, 1
• Motor restlessness and inability to remain still suggests severe neuropathic pain or CRPS, where patients cannot find a comfortable position 5
• Negative MRI effectively rules out serious structural pathology including metastatic disease, infection, fracture, and significant nerve compression that would require surgical intervention 1, 2, 3

Immediate Management Algorithm

First-Line Pharmacotherapy for Neuropathic Pain

• Initiate gabapentin (300 mg at bedtime, titrate up to 900-3600 mg/day in divided doses) or pregabalin (75 mg twice daily, titrate to 150-300 mg twice daily) as first-line agents for neuropathic pain 5
• Consider duloxetine (30-60 mg daily) or tricyclic antidepressants (amitriptyline 10-25 mg at bedtime, titrate slowly) as alternative or adjunctive first-line options for neuropathic pain 5
• Avoid opioids as first-line therapy given the neuropathic nature of the pain and lack of structural pathology 5, 3

Muscle Relaxants for Severe Spasm

• Cyclobenzaprine 5 mg three times daily may be added for muscle spasm, particularly in elderly patients where the 5 mg dose should be used initially and titrated slowly 6
• In elderly patients, cyclobenzaprine should be used with caution due to increased plasma concentrations and higher risk of CNS adverse events including hallucinations, confusion, and falls 6
• Avoid combining cyclobenzaprine with SSRIs, SNRIs, or tramadol due to risk of serotonin syndrome 6

Short-Term Adjunctive Therapy

• Acetaminophen or NSAIDs may provide modest benefit for any residual inflammatory component, though efficacy is limited in pure neuropathic pain 1, 2
• Topical lidocaine patches or capsaicin cream may be applied to the hypersensitive area for localized allodynia 5

When to Pursue Additional Imaging

Despite the negative MRI, certain red flags warrant reconsideration:

• Immediate repeat MRI with contrast if new fever, unexplained weight loss, or progressive neurological deficits develop, as these suggest infection or malignancy 1, 2, 3
• Consider bone scan or PET-CT if cancer history exists and symptoms worsen, as early metastatic disease can occasionally be MRI-negative 1
• CT scan may identify subtle fractures missed on MRI if trauma history or significant osteoporosis risk factors are present 2

However, in the absence of these red flags, repeating imaging is not indicated and delays appropriate neuropathic pain treatment 3, 4.

Specialist Referral Pathway

• Refer to pain management specialist within 2-4 weeks for consideration of interventional procedures if pharmacotherapy fails 5, 2
• Physical therapy focused on desensitization and graded motor imagery should be initiated early for CRPS-type presentations 5
• Psychological evaluation and cognitive-behavioral therapy should be considered given the chronic pain presentation and potential for central sensitization 5

Interventional Options if Conservative Management Fails

• Epidural steroid injections are NOT indicated when MRI shows no nerve root compression or structural pathology 5, 2
• Sympathetic nerve blocks may be considered if CRPS is strongly suspected based on clinical criteria 5
• Spinal cord stimulation may be an option for refractory neuropathic pain after 6 months of failed conservative management 5

Critical Pitfalls to Avoid

• Do not continue searching for structural pathology with repeated imaging when MRI is negative and symptoms suggest neuropathic pain—this delays appropriate treatment and increases healthcare costs 3, 4
• Do not attribute allodynia and hypersensitivity to "arthritis" or mechanical pain—these symptoms indicate neuropathic mechanisms requiring specific pharmacotherapy 1, 2
• Do not prescribe prolonged bed rest, as this leads to deconditioning and worsens disability in chronic pain syndromes 1
• In elderly patients, do not start cyclobenzaprine at 10 mg doses—always begin with 5 mg and titrate slowly due to increased plasma concentrations and fall risk 6
• Do not delay neuropathic pain medication while waiting for additional tests—early treatment of neuropathic pain improves outcomes 5

Expected Timeline and Follow-Up

• Reassess response to neuropathic pain medications at 2-4 weeks, as these agents require time to reach therapeutic effect 5, 2
• If no improvement after 6-8 weeks of optimized pharmacotherapy, refer to pain management specialist for consideration of interventional procedures or alternative diagnoses 5, 2
• Monitor for medication side effects closely in elderly patients, particularly sedation, confusion, and fall risk with gabapentinoids and cyclobenzaprine 6