Differential Diagnosis for Progressive Left Arm Weakness after Anterior Cervical Discectomy Decompression and Fusion

• Single Most Likely Diagnosis
  • Pseudarthrosis or hardware failure at the C5-6 level: This is a likely cause given the recent surgery and the presence of significant posterior osteophyte formation and uncovertebral spurring at C5-6, which could indicate inadequate decompression or instability.
• Other Likely Diagnoses
  • Recurrent or residual disc herniation at C5-6: The presence of significant posterior osteophyte formation and uncovertebral spurring at this level could also indicate a recurrent or residual disc herniation, which could be compressing the nerve root and causing the arm weakness.
  • C5 nerve root injury during surgery: The patient's symptoms could be due to an injury to the C5 nerve root during the recent surgery, which could have caused weakness in the left arm.
• Do Not Miss Diagnoses
  • Epidural hematoma: Although less likely, an epidural hematoma is a potentially life-threatening condition that could cause progressive arm weakness and must be ruled out with urgent imaging.
  • Infection (e.g., epidural abscess or discitis): Infection is a serious complication that could present with progressive neurological deficits and must be considered, especially in the postoperative period.
• Rare Diagnoses
  • Cervical spine instability or ligamentous injury: Although rare, instability or ligamentous injury at the C5-6 level could cause progressive arm weakness and should be considered if other diagnoses are ruled out.
  • Vertebral artery injury or thrombosis: This is a rare but potentially catastrophic complication of cervical spine surgery that could cause arm weakness due to vertebral artery injury or thrombosis.