Differential Diagnosis

The patient's symptoms of left-sided lower back pain, restricted flexion and left side flexion of the lumbar region, and loss of power on hip abduction, hip extension, and external rotation suggest a musculoskeletal or neurological issue. Here are the possible diagnoses categorized:

• Single most likely diagnosis
  • Lumbar Disc Herniation or Protrusion: This is the most likely diagnosis given the patient's symptoms of lower back pain, restricted movement, and loss of power in specific muscle groups. The pain and neurological deficits are consistent with nerve root compression, which can occur with a herniated or protruded disc.
• Other Likely diagnoses
  • Piriformis Syndrome: This condition, where the piriformis muscle compresses the sciatic nerve, could explain the patient's symptoms of lower back pain and loss of power in hip abduction and external rotation.
  • Lumbar Spondylosis or Spondylolisthesis: Degenerative changes or a slip of one vertebra over another could cause nerve root compression, leading to the patient's symptoms.
  • Gluteal Tendinopathy or Tear: Inflammation or a tear of the gluteal tendons could cause pain and weakness in hip abduction and extension.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Cauda Equina Syndrome: A rare but serious condition where the nerves in the spinal canal are compressed, causing severe neurological deficits. Although the patient's neuro exam is normal, any signs of urinary retention, fecal incontinence, or progressive neurological deficits would necessitate immediate investigation.
  • Spinal Infection (e.g., Discitis or Osteomyelitis): Infection of the spine could cause severe back pain, neurological deficits, and systemic symptoms. A history of recent travel or immune compromise might increase the suspicion for this diagnosis.
  • Spinal Tumor: A tumor in the spine could cause back pain, neurological deficits, and systemic symptoms. Although rare, this diagnosis should be considered, especially if the patient has a history of cancer or unexplained weight loss.
• Rare diagnoses
  • Lumbar Spinal Stenosis: Narrowing of the spinal canal could cause back pain, neurological deficits, and symptoms worsened by walking or standing. This condition is more common in older adults.
  • Sacroiliac Joint Dysfunction: Inflammation or dysfunction of the sacroiliac joint could cause lower back pain and stiffness, but this would not typically cause the specific pattern of muscle weakness seen in this patient.