What is the appropriate diagnosis and management for a patient presenting with lower limb paresis, plantar flexor weakness, and spinal tenderness?

Diagnosis and Management of Lower Limb Paresis with Plantar Flexor Weakness and Spinal Tenderness

This presentation requires urgent evaluation for spinal cord pathology, specifically vertebral compression fracture with potential cord compression or acute spinal cord injury, as point tenderness at the spinous process combined with lower limb motor deficits indicates serious neurological compromise requiring immediate intervention. 1

Immediate Clinical Assessment

Critical Red Flags to Identify

• Document baseline lower limb neurological function immediately to facilitate rapid assessment of any deterioration, as this is essential for detecting post-procedural or progressive neurological changes 1
• Assess for motor weakness severity and sensory deficits to distinguish between viable limb (Category I), marginally threatened (Category IIa), immediately threatened (Category IIb), or irreversibly damaged (Category III) presentations 1
• Evaluate for saddle anesthesia or bowel/bladder dysfunction, which would indicate cauda equina syndrome requiring emergency surgical decompression 2
• Perform handheld continuous-wave Doppler examination of dorsalis pedis and posterior tibial pulses bilaterally, as pulse palpation alone is inaccurate and loss of Dopplerable arterial signal indicates threatened limb 1

Specific Physical Examination Findings

• Point tenderness at the spinous process of a fractured vertebra is the classic finding for vertebral compression fracture, and when combined with lower limb paresis, suggests neurological compromise 1
• Test plantar flexor strength systematically in a rostro-caudal manner from hip to toes to localize the level of neurological involvement 3
• Distinguish between upper and lower motor neuron signs: presence of hyperreflexia, spasticity, or Babinski sign suggests spinal cord pathology rather than peripheral nerve or vascular etiology 4, 5

Diagnostic Workup Priority

Imaging Requirements

• Obtain urgent MRI of the lumbar and thoracic spine if back pain is present with motor weakness or upper motor neuron signs, as this is the gold standard for identifying spinal cord compression, epidural hematoma, or acute spinal cord injury 2
• CT should be rapidly available in case of clinical deterioration during any procedural intervention 1
• Do not delay imaging for laboratory work when neurological deficits are present, as the time window for reversible spinal cord injury is limited 1

Vascular Assessment

• Measure ankle-brachial index (ABI) bilaterally as the initial test to confirm or exclude peripheral artery disease, with ABI ≤0.90 confirming PAD, 0.91-0.99 borderline, and >1.40 indicating non-compressible arteries requiring toe-brachial index 6, 7
• Obtain bilateral arm blood pressures to identify subclavian artery stenosis, with difference >15-20 mmHg considered abnormal 6, 7
• If acute limb ischemia is suspected (pain, pallor, pulselessness, poikilothermia, paralysis, paresthesia), this requires emergent revascularization within 6 hours for threatened limbs 1

Management Algorithm

If Spinal Pathology is Confirmed

For vertebral compression fracture with neurological compromise:

• Significant spinal canal stenosis or compressive myelopathy from retropulsed fracture fragment is a relative contraindication to vertebral augmentation, and surgical decompression should be considered first 1
• Radiculopathy in excess of local vertebral pain is a relative contraindication to vertebral augmentation alone 1
• If there is clear disparity between physical examination findings and imaging, vertebral augmentation should not be performed 1

For acute spinal cord injury with neuropathic pain:

• Pregabalin 150-600 mg/day is FDA-approved for management of neuropathic pain associated with spinal cord injury, with efficacy demonstrated in reducing pain scores by ≥30% and ≥50% from baseline 8
• Pain reduction may occur as early as week 1 and should be titrated over 3-4 weeks to effective and tolerable dose 8

If Peripheral Artery Disease is Confirmed

For viable limbs (Category I):

• Revascularization should be performed urgently within 6-24 hours 1
• Initiate guideline-directed medical therapy immediately: antiplatelet therapy, high-intensity statin, blood pressure control, smoking cessation, and diabetes management 7

For marginally or immediately threatened limbs (Category IIa/IIb):

• Revascularization must be performed emergently within 6 hours 1
• Administer systemic anticoagulation with heparin immediately unless contraindicated 1
• The revascularization technique should provide the most rapid restoration of arterial flow with least risk, considering catheter-directed thrombolysis versus surgical thromboembolectomy based on local expertise 1

For irreversibly damaged limbs (Category III):

• Prolonged ischemia >6-8 hours with insensate and immobile limb makes revascularization unlikely to achieve limb salvage, and risks of reconstruction outweigh benefits 1

Critical Pitfalls to Avoid

• Do not dismiss paresthesia and weakness as "just neuropathy" without vascular assessment, as PAD often presents with atypical symptoms including paresthesia rather than classic claudication 7
• Do not delay intervention for "conservative management" when motor deficits are present, as skeletal muscle tolerates ischemia for only 4-6 hours and spinal cord compression can cause irreversible damage 1
• Do not miss the combination of spinal tenderness with bilateral symptoms, which suggests central pathology rather than peripheral nerve or vascular disease 1, 2
• Do not perform vertebral augmentation if radiculopathy exceeds local vertebral pain or if there is significant spinal canal stenosis, as these are contraindications requiring alternative management 1

Post-Intervention Monitoring

• Assess vital signs and lower limb neurological function at regular intervals after any spinal or vascular intervention 1
• Supervised ambulation should occur only after appropriate observation period with documented stable neurological examination 1
• Monitor for symptom progression with regular pulse and foot assessment in PAD patients 7