Lumbar Disc Herniation: The most common cause of back pain at the L4 and L5 levels, often resulting from degenerative disc disease, trauma, or lifting heavy objects, leading to nerve root compression and pain.

Lumbar Spondylosis: A degenerative condition affecting the lumbar spine, leading to pain and stiffness due to wear and tear on the joints and discs.
Lumbar Facet Joint Syndrome: Inflammation or degeneration of the facet joints in the lumbar spine, causing pain and stiffness, especially with extension and rotation.
Ligament Sprain or Muscle Strain: Overstretching or tearing of the ligaments or muscles in the lower back, often due to sudden twisting, bending, or lifting, leading to pain and limited mobility.

Cauda Equina Syndrome: A serious condition where the nerves in the spinal canal are compressed, leading to severe pain, numbness, and weakness in the legs, as well as bladder and bowel dysfunction. Prompt recognition and treatment are crucial to prevent permanent damage.
Spinal Infection (e.g., Osteomyelitis, Discitis): Infections of the spine, which can cause severe back pain, fever, and neurological deficits. Early diagnosis and treatment are essential to prevent serious complications.
Spinal Tumor: A tumor in the spine, which can cause back pain, neurological deficits, and systemic symptoms. Although rare, it is a critical diagnosis to consider to ensure timely treatment.

Spondylolisthesis: A condition where a vertebra slips out of place, potentially causing back pain, neurological symptoms, and instability.
Tarlov Cyst: A rare condition where a cyst forms in the nerve roots of the spine, leading to back pain, numbness, and weakness.
Arachnoiditis: Inflammation of the arachnoid membrane surrounding the spinal cord, causing back pain, numbness, and neurological deficits.