see also:

• painful ear
• scalp folliculitis
• headache

• the adult patient presenting with a painful scalp is not uncommon and can be difficult to diagnose and treat

• anterior and superior scalp:
  • supplied by the supratrochlear and supraorbital nerves (branches of CN V₁)
• temporal region:
  • supplied by:
    • the zygomaticotemporal (CN V₂)
    • the auriculotemporal nerve (CN V₃):
      • also supplies the outer surface of the tympanic membrane (ant/inf)
      • has a long, winding path from deep inside the skull up to the side of the head.
      • as it passes through tight muscular spaces, wraps around blood vessels, and travels inside glands, it is highly vulnerable to irritation, entrapment, and compression especially at either:
        • the infratemporal fossa (deep muscular space):
          • deep behind the mandible, the nerve emerges from two roots that encircle the middle meningeal artery.
          • here, it sits directly adjacent to the lateral pterygoid muscle
          • chronic clenching, teeth grinding (bruxism), or jaw dysfunction can cause hypertonicity or spasms in the lateral pterygoid muscle
        • the temporomandibular joint (TMJ):
          • as the nerve travels outward, it turns upward and passes directly behind the neck of the mandibular condyle
          • this places it right against the posterior joint capsule
          • if the TMJ is inflamed, or if the jaw condyle is structurally positioned too far backward (posterior displacement due to malocclusion), it mechanically crushes or pinches the nerve against the skull base
        • parotid gland:
          • the nerve travels directly through the upper portion of the parotid gland and thus can be damaged in surgery
            • can also lead to Frey’s syndrome, where damaged salivary nerve fibers mistakenly regrow into sweat glands, causing flushing and sweating when eating)
        • the preauricular fascia and superficial temporal artery:
          • as the nerve ascends onto the side of the head in front of the ear, it passes through tight bands of connective tissue (preauricular fascial bands)
          • in 80% of people, it closely intertwines with or is crossed over by the superficial temporal artery
            • pulsing of an overlying or tightly bound superficial temporal artery can chronically irritate the nerve.
            • this mechanical irritation is a recognized trigger for temple-localized migraine headaches and nerve pain
          • spontaneous constriction or thickening of the fascial tissue layers just in front of the upper ear can bind the nerve, causing localized auriculotemporal neuralgia
      • see also painful ear for nerve supply of the ear
• posterior parietal region / upper area behind the ear:
  • supplied by the lesser occipital nerve (originates from the anterior rami of the second and third cervical spinal nerves (C2 and C3), forming part of the superficial cervical plexus)
• posterior scalp (occiput), vertex, small section of upper neck:
  • supplied by the greater occipital nerve (originates from the medial branch of the posterior ramus of the second cervical spinal nerve (C2))
    • before piercing the fascia to become a cutaneous nerve, it provides motor branches to several deep muscles of the upper neck, including semispinalis capitis and obliquus capitis inferior
    • the C2 dorsal ramus before it becomes the greater occipital nerve also supplies the C2–C3 facet joint
    • osteoarthritis, instability, or whiplash injuries to the upper cervical joints (ie. the C1–C2 atlantoaxial joint or C2–C3 facet joint) can pinch, inflame, or irritate the greater occipital nerve and this can be a trigger point for cervicogenic headaches and migraines hence the role of the greater occipital nerve block (GON block)
• lower posterior scalp, the skin at the base of the skull, the upper nape of the neck and C2–C3 facet joint
  • supplied by the third occipital nerve (a branch of the posterior ramus of the third cervical spinal nerve (C3) )

• the main motor root of the facial nerve proper
  • the occipitofrontalis muscle via the posterior auricular and temporal branches

• papules and pustules of scalp folliculitis
• abscess / boils
• other scalp dermatologic conditions
• tender lymph nodes (pre or post auricular, suboccipital)
  • sub-occipital / posterior Cx enlarged LNs may be due to:
    • scalp infection or inflammation
    • scalp or regional neoplasia
    • EBV / glandular fever / infectious mononucleosis
    • cytomegalovirus (CMV)
    • rubella
    • lymphoma
• temporal arteritis
• mastoiditis
• see also painful ear

• herpes zoster (shingles)
  • unilateral dermatomal pattern
  • NB. the pain may commence before the blisters are evident
• eczema herpeticum
  • Herpes simplex virus (HSV) infection of eczematous skin
• dermatitis herpetiformis
  • usually at suboccipital areas (and other parts of body) and in patients with coeliac disease

• scalp dermatoses
  • scalp skin is usually inflamed and it is not usually unilateral or dermatomal
• temporal arteritis
  • consider C reactive protein (CRP) or erythrocyte sedimentation rate (ESR) if temporal region is tender, especially in older adults
  • see polymyalgia rheumatica
• mastoiditis
  • tenderness only over the mastoid region
• scalp allodynia / neuralgia
  • usually due to irritation of a nerve supplying sensation to the scalp
    • may be local irritation:
      • local pressure area
      • local trauma
      • local pustule or papule
    • may be due to central sensitisation from migraine
    • may be post-herpetic neuralgia
    • may be nummular allodynia
      • a relatively rare idiopathic form of primary headache¹⁾ confined to a 1-6cm, round or oval, well-demarcated area of the scalp especially the parietal region
      • without any spontaneous or throbbing headache pain
      • not accompanied by nausea, vomiting, rhinorrhea, lacrimation, conjunctival injection, light or sound sensitivity or focal neurologic symptoms
      • appears to originate peripherally (ie. from scalp structures rather than from CNS causes) perhaps from transdiploic and intradiploic nerves given the lack of response to peripheral nerve blocks although botox may help - onset of action is 6 to 10 days, and the effect lasts up to 14 weeks²⁾
      • migraine and tension headaches may be concurrently present with a nummular headache but are not related
      • pain lasting minutes, hours or days with a remitting or unremitting course being either continuous or interrupted by spontaneous remissions lasting weeks and months
      • 69% appear to have autoimmune disorders, most commonly, a positive ANA
      • 1st described in 2002
      • intermittent tactile nummular allodynia (ITNA)
        • episodes can occur 6–7 times per year, each lasting about four days³⁾
  • hypersensitive normal looking scalp with pain on light touch or movement of scalp muscles
  • unilatereal and follows nerve distribution rather than purely dermatomal
  • auriculotemporal neuralgia
    • causes allodynia or stabbing/throbbing pains of temporal region of scalp, tragus of ear +/- deep ear pain as it also supplies the tympanic membrane
  • lesser occipital nerve irritation
    • supplies posterior parietal area of scalp and post-auricular areas and can cause pain from base of skull and allodynia of posterior parietal scalp
  • greater occipital nerve irritation
    • generally causes occipital and vertex scalp pain +/- triggering of migraines or cervicogenic headaches

• post-herpetic neuralgia
  • unilateral dermatomal pattern
• see also headache
  • tension headache
  • cervicogenic headache