title: Frontolateral pins for halo ring placement: reassessment of a common neurosurgical procedure with CT measurements of skull thickness.
abstract: OBJECTIVE
  Halo orthosis placement is a common neurosurgical procedure for the treatment of cervical spine injuries. Frontal sinus puncture by the anterior pins may occur using standard techniques, and up to 30% are dissatisfied with forehead scarring, especially women and African Americans.
  
  
  METHODS
  The authors describe a frontolateral (FL) anterior pin site placement supported by high-resolution CT scan skull thickness measurements. The standard supraorbital (SO) pin site is several centimeters above the lateral orbit, whereas the FL pin site is 2-3 cm posterolateral to the SO site. Frontolateral placement is just anterior to the temporalis muscle close to a triangular anterior projection of the temporal hairline. For quantitative information on skull thickness at the SO and FT pin sites, thin 0.625-mm CT scan measurements of the outer table, diploic space, and inner table were obtained in 40 adults (80 sites).
  
  
  RESULTS
  The mean values for total skull thickness at the SO and FT sites were not significantly different. The inner table was significantly thicker at the FL site in both males and females, buttressed by the nearby greater sphenoid wing. The mean total skull thickness was significantly less in females than in males, but the values were not significantly different at the SO and FL sites.
  
  
  CONCLUSIONS
  The FL and SO anterior pin sites are comparable with respect to skull thickness CT measurements, with a significantly thicker inner table at the FL site. In the senior author's experience, the FL anterior pin site yielded secure fixation without skull perforation, neurovascular injury, or propensity to infection. The cosmetic result of the FL site is more acceptable, and the authors recommend its general usage be adopted.
authors.affiliation: Department of Neurosurgery, NorthShore University HealthSystem, Evanston;
authors.forename: James L
authors.initials: JL
authors.lastname: Stone
authors.forename: Aditi
authors.initials: A
authors.lastname: Gulabani
authors.forename: Gleb
authors.initials: G
authors.lastname: Gorelick
authors.forename: Siddharth N K
authors.initials: SN
authors.lastname: Vannemreddy
authors.forename: Prasad S S V
authors.initials: PS
authors.lastname: Vannemreddy
mesh_terms: D000328:Adult; D000367:Age Factors; D001858:Bone Nails / Q000592:standards*; D002574:Cervical Vertebrae / Q000293:injuries; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D019635:Neurosurgical Procedures / Q000295:instrumentation / Q000592:standards*; D009989:Orthotic Devices / Q000009:adverse effects / Q000592:standards*; D012737:Sex Factors; D012886:Skull / Q000000981:diagnostic imaging*; D013124:Spinal Injuries / Q000628:therapy*; D014057:Tomography, X-Ray Computed / Q000295:instrumentation / Q000379:methods*; D055815:Young Adult