Headache (unspecified) → R51.9

Post-traumatic headache → G44.3

Occipital neuralgia → M54.81 

C2–3 → C3 | DDD M50.31 | HNP M50.21 | Radic M50.11 | Cervicalgia M54.2
C3–4 → C4 | DDD M50.31 | HNP M50.21 | Radic M50.11
C4–5 → C5 | DDD M50.32 | HNP M50.22 | Radic M50.12
C5–6 → C6 | DDD M50.32 | HNP M50.22 | Radic M50.12
C6–7 → C7 | DDD M50.32 | HNP M50.22 | Radic M50.12
C7–T1 → C8 | DDD M50.33 | HNP M50.23 | Radic M50.13

T1–12 → same | DDD M51.34 | HNP M51.24 | Radic M51.14 | Thoracic pain M54.6

T12–L1 → T12 | DDD M51.36 | HNP M51.26 | Radic M51.16
L1–2 → L2 | DDD M51.36 | HNP M51.26 | Radic M51.16
L2–3 → L3 | DDD M51.36 | HNP M51.26 | Radic M51.16
L3–4 → L4 | DDD M51.36 | HNP M51.26 | Radic M51.16
L4–5 → L5 | DDD M51.36 | HNP M51.26 | Radic M51.16
L5–S1 → S1 | DDD M51.37 | HNP M51.27 | Radic M51.17 | LBP M54.50

SI / SACRAL / COCCYX (CONDENSED)

SI joint pain/dysfunction → M53.3 | Sacroiliitis M46.1 | SI sprain S33.6xA/D | SI arthropathy M12.9
Sacral/sacrococcygeal spondylosis → M47.818 | Coccydynia M53.3
Piriformis syndrome → L G57.02 | R G57.01 | Cluneal neuralgia M79.2
Lumbar sprain → S33.5xxA/D | Lumbar strain S39.012 | Muscle spasm M62.830