Upper lumbar discs have been reported as only L1-L2 and L2-L3 by some authors, and by others as T12-L1, L1-L2, and L2-L3.
Most previous studies of upper lumbar disc herniations included the L1-L2, L2-L3, and L3-L4 levels. Upper lumbar disc herniations have been reported to occur with a frequency of less than 5% of all disc herniations.
Among these reported cases, herniations at the L3-L4 level comprise 70-83% of all upper lumbar disc herniations.
However, the anatomical characteristics of L3-L4 discs are more similar to lower levels, and its surgical outcome is significantly different from that of L1-L2 and L2-L3. Therefore, the L3-L4 level might be excluded from the upper lumbar disc. Incidence of herniated upper lumbar discs defined as only L1-L2 and L2-L3 are known to comprise approximately 1 to 2% of all herniated lumbar discs 1).