Salient Points

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  Roughly 40% of patients with migraine headaches experience pain in the occipital area.

  
  
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  Many of these patients have a history of whiplash injury and sometimes the pain is related to occipital neuralgia rather than migraine headaches.

  
  
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  The headaches related to this site start from the paramedian occipital area where the nerve emerges from the semispinalis muscle (3-3.5 cm caudal to the occipital tuberosity and 1.5 cm from the midline or laterally).

  
  
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  To detect the occipital trigger site, the patient is asked to point to the migraine headache starting site with a fingertip and a Doppler signal is searched; if present, the site is marked and later tattooed with brilliant green after induction of anesthesia.

  
  
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  When a Doppler signal is identified, it is usually several centimeters lateral to the site of the emergence of the nerve from the muscle and often where the nerve is intertwined with the occipital artery or its branches.

  
  
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  With the patient in a sitting position, the midline of the occipital area is identified by palpating the cervical spines and marked.

  
  
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  With the patient in a supine position, general anesthesia is induced and the patient is turned to the prone position with the shoulders pulled caudally and taped to the bed and the breasts and chest supported with folded rolls.

  
  
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  Under sterile conditions, an incision is made about 4.5 cm in length at the midline extending from the hairline to the occipital tuberosity after injection of the area with 1% lidocaine containing 1:100,000 epinephrine.

  
  
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  The skin incision is taken through the trapezius fascia and the muscle, if it extends to the midline, 0.5 to 0.75 cm from the midline on each sided while keeping about a 1 – 1.5-cm width of the midline raphe intact.

  
  
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  The trapezius muscle with its oblique fibers may or may not extend to the midline.

  
  
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  Deep to the trapezius muscle and the underlying fascia, the nerve can be identified with minimal dissection using a pair of Metzenbaum scissors.

  
  
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  The most common reason for the difficulty in locating the greater occipital nerve is the dissection being conducted superficial to the trapezius muscle instead of the semispinalis capitis muscle.

  
  
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  If the nerve appears too small, it is likely that there is intramuscular branching and it is crucial to look for additional nerve branches emerging from the muscle.

  
  
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  As the nerve comes into view, it is isolated with blunt dissection and a vessel loop is passed around it.

  
  
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  A 2-cm-long block of the muscle between the greater occipital nerve and the midline raphe is isolated and removed using the coagulation power of the cautery.

  
  
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  A triangular piece of the trapezius fascia and muscle fibers (if present) are then removed laterally overlying the nerve.

  
  
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  The fascia overlying the nerve is released in a manner similar to carpal tunnel release, the endpoint being visualization of the subcutaneous tissues.

  
  
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  The vessels commonly surrounding the nerve are isolated and cauterized with a bipolar cautery and transected.

  
  
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  On patients who have an identifiable Doppler signal, the tattoo marks that were placed earlier are located internally and the vessels are identified and cauterized.

  
  
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  Should the vessel not be visualized internally in the tattooed area through the main incision, a separate skin incision is made to remove the vessels identified with the Doppler.

  
  
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  A wedge of muscle is removed lateral to the nerve to accommodate the subcutaneous flap only if the nerve is too medial to have a straighter course without tension if it has to wrap around the medial border of the semispinalis capitis muscle.

  
  
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  The third occipital nerve is either decompressed or transected as far caudally as possible and allowed to retract in the semispinalis capitis muscle, whenever it is encountered.

  
  
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  A caudally based subcutaneous flap approximately 2 to 2.5 cm in diameter is elevated cephalad to the course of the nerve and it is placed under the nerve on each side while avoiding constriction of the nerve.

  
  
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  The flap is attached to the midline with 5-0 Monocryl suture if the procedure is done unilaterally.

  
  
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  If the procedure is done bilaterally, the suture is passed through one flap and passed under the midline raphe to catch the opposite flap and passed through the midline raphe again and tied to approximate the two flaps to the midline raphe with one stitch as deep as possible.

  
  
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  The trocar attached to the TLS drain is passed through the subcutaneous tissues and retrieved through the skin above the upper limits of the skin incision, and passed through the midline raphe to drain both sides and is fixed in position using 5-0 plain catgut.

  
  
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  The deep layer is repaired using an inverted 5-0 Monocryl or Vicryl attaching the subcutaneous tissues to the midline raphe and the skin is repaired using 5-0 plain catgut running locking suture.

  
  
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  The drain is removed in 3 to 4 days, depending on the amount of the drainage.