Empty Thecal sac sign in:
Arachnoiditis
Tethered Cord syndrome
Veebral osteomyelitis
Discitis
* Arachnoiditis is chronic inflammation of meninges and can occur after intrathecal injection of contrast agent, infections, drugs leading to nerve root getting adhered into peripheral meninges giving the appearance of EMPTY THECAL SAC sign on T2 weighted MRI * Tethered Cord Syndrome is when the spinal cord extends below the elbow level due to lipoma of Filum terminal or post op scarring/ adhesions that prevent spinal cord from ascending upward and it remains below L2 level.