Author:
Toby Bown
Reviewer:
Kai KnudsenUpdated:
27 August, 2025
Blockade of individual nerves to the scalp, as opposed to infiltration in the incision line. Described originally in 1986 as “scalp block” for use in awake craniotomy
Scalp block
- Blockade of individual nerves to the scalp, as opposed to infiltration in the incision line
- Described originally in 1986 as “scalp block” for use in awake craniotomy
Why?
- Historically post craniotomy pain has been undertreated
- Better analgesia than infiltration, with lower doses
- Enhances analgesia without the sedating properties of opioids (plus N&V, respiratory depression, hypercapnia)
- Improved postop neurological assessment
- Hemodynamic stability, especially if prior to pin insertion
- Trauma/lacerations
- Migraine/chronic pain
Historical view that craniotomy is not painful + that pain Rx considered dangerous
When?
- Prior to pinning/incision
- Post op prior to extubation
- AWAKE surgery
- Rescue on the ward?
- Emergency ward– scalp lacerations etc.
Scalp block
- Nerves come from 2 different places:
- Branch of trigeminal nerve (cranial nerve V) cervical nerves (plexus + posterior rami C2/3 nerve root)
- Usually 6 nerve blocks:
- Cranial nerve V:
- Supraorbital (V1)
- Supratrochlear (V1)
- Zygomaticotemporal (V2)
- Auricotemporal (V3)
- Greater occipital (posterior ramus)
- Lesser occipital (cervical plexus)
- Also: greater auricular nerve (CP) and 3rd occipital nerve (post ramus (C3)
Supraorbital/supratrochlear nerves (V1)
- Supraorbital notch, ≈ 3 cm from the midline, 1 mL just below the orbital rim
- Supratrochlear nerve lies just medial to the supraorbital nerve (0,9 – 1,3 cm). Junction of the orbital and nasal bones. 1 mL
- Care with the eye! Use the non-dominant hand as a backstop
Auricotemporal nerve (V3)
- Blocked above the posterior portion of the zygoma, anterior to the ear and behind the superficial temporal artery
- Use a small needle anterior and superior to the tragus
- Careful with the temporal artery
Zygomaticotemporal (V2)
- Challenging block, extensive and early branching
- Deep and superficial injections are required
- Advance the needle along the lateral orbital rim, 1-1,7 cm posterior to the frontozygomatic suture and 2,2 cm above the upper margin of the zygomatic arch. 2 mL
Greater occipital nerve
- Lies 2/3 along a line from the mastoid to the occipital protuberance, along the superior nuchal line
- Medial to the occipital artery
- Considerable inter-patient variability according to NYSORA, but US can be helpful here
Lesser occipital nerve block
- Lateral to the greater occipital nerve block along the same line
Evidence?
- Previous reviews (search from 2018) showed inconsistent pain reduction after craniotomy, with low quality evidence and few RCTS
- New meta-analysis from 2023 found 22 RCTs that met inclusion criteria
- Pain reduced at all time points from 2–72 hours (↓ VAS by 0,75 – 1,4)
- Opioid consumption ↓ 16 MME (morphine mg equivalents) @ 24 hrs. Less risk PONV (odds ratio 0,65)
Complications?
- Appears to have low complication rate
- The above study found no cases of infection, hematoma, nerve palsy
- Risks from LA OD, facial nerve paralysis, subarachnoid injection with occipital block
- General the evidence in the meta-analysis from 2023 found more robust evidence in favour of scalp block than previous studies
- The authors “recommend consideration of scalp blocks for scheduled craniotomies in ERAS or neurosurgical clinical care pathways”
Pain after neurosurgery
- Hypertension/vomiting -> increased risk for post op bleeding due to ↑ ICP
- Acute pain reduction may ↓ chronic post craniotomy headache
- Opioids may mask neurosurgical complications. About 60% of patients undergoing craniotomy experience moderate – severe pain
Trigeminal nerve (CN V)
- The most complex of the cranial nerves!
- 3 major branches (tri..): ophthalmic (V1), maxillary (V2), mandibular (V3)
- Sensation to the forehead, temple, face, mouth and palate
- Dermatomes have sharp borders
- V1, V2 and V3 converge on the trigeminal (gasserian) ganglion in Meckel’s cave, before separating and exiting the skull through the superior orbital fissure, the foramen rotundum and the foramen ovale respectively
