zones showing nerves_moved.jpg 3_moved.jpg shot 2012-10-14 at 11.09.23 am.jpg
  • Fixes skull relative to torso 
    • provides most rigid form of cervical spine external immobilization
    • ideal for upper C-spine injury
  • Allows intercalated paradoxical motion in the subaxial cervical spine
    • therefore not ideal for lower cervical spine injuries (lateral bending least controlled) 
      • "snaking phenomenon"
        • recumbent lateral radiograph shows focal kyphosis in midcervical spine 
        • yet, upright lateral radiograph shows maintained lordosis in midcervical spine
  • Adult
    • definitive treatment of cervical spine trauma including
      • occipital condyle fx
      • occipitocervical dislocation
      • stable Type II atlas fx (stable Jefferson fx)
      • type II odontoid fractures in young patients 
      • type II and IIA hangman’s fractures
    • adjunctive postoperative stabilization following cervical spine surgery
  • Pediatric
    • definitive treatment for
      • atlanto-occipital dissociation
      • Jefferson fractures (burst fracture of C1)
      • atlas fractures
      • unstable odontoid fractures
      • persistent atlanto-axial rotatory subluxation 
      • C1-C2 dissociations
      • subaxial cervical spine trauma
    • preoperative reduction in the patients with spinal deformity
  • Absolute
    • cranial fractures
    • infection
    • severe soft-tissue injury
      • especially near proposed pin sites
  • Relative
    • polytrauma
    • severe chest trauma
    • barrel-shaped chest
    • obesity
    • advanced age
      • recent evidence demonstrates an unacceptably high mortality rate in patients aged 79 years and older (21%)
  • CT scan prior to halo application
    • indications
      • clinical suspicion for cranial fracture
      • children younger than 10 to determine thickness of bone
Adult Technique
  • Adults
    • torque
      • tighten to 8 inch-pounds of torque
    • location
      • total of 4 pins
      • 2 anterior pins 
        • safe zone is a 1 cm region just above the lateral one third of the orbit (eyebrow) at or below the equator of the skull  
          • this is anterior and medial to temporalis fossa/temporalis muscle
          • this is lateral to supraorbital nerve 
      • 2 posterior pins
        • placed on opposite side of ring from anterior pins
    • followup care
      • can have patient return on day 2 to tighten again
      • proper pin and halo care can be done to minimize chance of infection
Pediatric Technique
  • Pediatrics 
    • torque
      • best construct involves more pins with less torque 
        • total of 6-8 pins
        • lower torque (2-4 in-lbs or "finger-tight") 
    • pin locations
      • place anterior pins lateral enough to avoid injury to the frontal sinus, supratrochlear and supraorbital nerves 
      • place pins anterior enough to avoid the temporalis muscle
      • place pins posteriorly opposite from anterior pins
    • brace/vest
      • custom fitted vest for children > 2 years
      • children <2 yrs should use Minerva cast
    • CT scans may help in pin placement
      • can help facilitate avoiding cranial sutures
      • can  help facilitate avoiding thin regions of skull
      • help limit risk of complications 
  • Loosening (36%)
    • can be treated with retightening
    • if continues to loosen, should be treated with pin exchange
  • Infection (20%)
    • can especially occur with posterior pin in temporalis fossa because
      • pins hidden in hairline
      • bone is thin
      • temporalis muscle moves with chewing
    • can be treated with oral antibiotics if pin not loose 
      • if pin infection and loose then pin should be removed
  • Discomfort (18%)
    • treated by loosening skin around pin
  • Dural puncture (1%)
  • Abducens nerve palsy 
    • epidemiology
      • is most commonly injured cranial nerve with halo
    • pathophysiology
      • thought to be a traction injury to cranial nerve 6, which affects abducens nerve (innervate lateral rectus muscles) 
    • symptoms
      • diplopia
    • physical exam
      • loss of lateral gaze on affected side 
    • treatment
      • observation as most resolve spontaneously
  • Supraorbital nerve palsy  
    • injured by medially placed anterior pins
  • Supratrochlear nerve palsy  
    • injured by medially placed anterior pins
  • Medical complications
    • pneumonia
    • ARDS
    • arrhythmia

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Questions (4)

(OBQ11.38) A 27-year-old male is an unrestrained passenger in a motor vehicle accident. He was medically stabilized in the emergency room. His initial injury CT scans are seen in Figures A and B. He is neurologically intact and placed in a halo fixator prior to surgical treatment. What is the most common neurologic complication with halo traction? Review Topic


Weakness in biting and chewing strength




Deficit in medial and downward eye movement




Deficit in lateral eye movement




Inability to close eyes against resistance




Tongue deviation toward the affected side



Select Answer to see Preferred Response


Figures A and B depict a patient with an Type II odontoid fracture. Cranial nerve VI palsy is the most common nerve palsy associated with halo cervical traction. A cranial nerve VI palsy would result in paralysis of the lateral rectus, causing a deficit in lateral eye movement. The cranial nerves and functions are in Illustration A.

Halo fixation is indicated for a number of conditions in the cervical spine including definitive treatment for fractures and preoperative reduction. In adults, four pins are placed at 6-8in/lbs. The safe zone is defined 1cm superior to the outer 2/3 of the orbit. Absolute contraindications include active infection, cranial fractures and severe soft-tissue injury at pin sites. Pin loosening is the most common complication in adults, followed by pin site infection.

Wilkens et al investigated cranial nerve complications with halo immobilization and traction in 70 patients. They found the sixth cranial nerve was most commonly affected by distraction and resulted in weakness in lateral gaze. They emphasize that frequent monitoring of the patients in skeletal traction is necessary, and prompt recognition of the clinical signs of these complications must be stressed.

Bono et al report halo immobilization can be used for the definitive treatment of cervical spine trauma, preoperative reduction in the patient with spinal deformity, and adjunctive postoperative stabilization following cervical spine surgery. They state skull fracture, infection, and severe soft-tissue injury at the pin sites as absolute contraindications. Relative contraindications include severe chest trauma, obesity, advanced age, and a barrel-shaped chest.

Figure A shows a sagittal CT showing a Type II odontoid fracture with anterior displacement. Figure B is an axial CT at the level of the odontoid again showing anterior diplacement of the dens. Illustration A lists the cranial nerve. Illustration B & C illustrate how to place a halo fixator. Illustration D shows the safe zone for placement of your anterior halo pin.


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(OBQ10.99) With halo immobilization the anterior pin should be placed in which of the following regions in Figure A to avoid injury to the supraorbital nerve and optimize stability? Review Topic


Region A




Region B




Region C




Region D




Region E



Select Answer to see Preferred Response


The safe zone for anterior pin insertion with halo immobilization is an approximately 1-cm region just above the lateral one third of the orbit (eyebrow) at or below the equator of the skull. More lateral pin insertion risks penetration of the thin temporal bone. More medial positioning risks injury to the supraorbital and supratrochlear nerves (see Illustration A). An injury to the supraorbital nerve may lead to pain and numbness over the medial one third of the eyebrow. The supratrochlear nerve supplies sensation medial and inferior to the supraorbital sensory distribution. Regions A, B, and C are all above the equator of the skull and would not be ideal from a biomechanical perspective. The review article by Bono explains the history, indications, proper placement, and complications of halo immobilization.


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(OBQ09.110) The halo vest is most effective at controlling which of the following spinal motions? Review Topic


Rotation at the atlantoaxial joint




Flexion and extension in the subaxial cervical spine




Rotation in the subaxial cervical spine




Lateral bend in the subaxial cervical spine




Flexion and extension at the cervicothoracic junction



Select Answer to see Preferred Response


The Halo vest immobilizes the skull relative to the torso. Therefore is is ideal for controlling motion at upper cervical spine (occipitocervical junction and atlantoaxial junction. Halo immobilization allows for intercalated paradoxical motion in the subaxial cervical spine, and is therefore less ideal for lower cervical spine injuries.

Ivancic et al performed an invitro study measuring motion of cervical spine specimens with the variables of a normally applied halo, a loose vest, a loose superstructure, and an absent posterior uprights. They found that lateral bending was increased at the C6-7 level when there was a loose superstructure.

Johnson et al evaluated the ability of different cervical orthoses to control cervical range of motion at each cervical intervertebral joint. At the atlanto-axial joint, the halo vest restricted flexion-extension by 75%, which compared to only 45% by conventional cervical braces. The halo vest was less effective at controlling motion in the subaxial cervical spine below C3.

Bono et al reviews the literature and discusses the indications, contraindications, and complications for halo immobilization. They recommend the halo can be used for definitive treatment of C1 burst (Jefferson) fracture and type II and III odontoid fractures. Absolute contraindications include cranial fracture, infection, and severe soft-tissue injury at the proposed pin sites. They discuss the high mortality rate associated with using halo immobilization in the elderly population.

Illustration A shows the table from the Johnson articles that compares the effectiveness of different orthosis at controlling different types of motion (combined measurement from occiput to T1)

Incorrect Answers:
Answers 2,3,4,5: The halo vest is less effective at controlling motion in the subaxial cervical spine and cervicothoracic junction than at the atlanto-axial joint.


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(OBQ07.224) A 20-year-old man presents with a type III odontoid fracture and undergoes halo application. What nerve structure is in danger if the anterior pins are placed too medially? Review Topic


Facial nerve




Supraorbital nerve




Abducens nerve




Zygomaticotemporal nerve




Zygomaticofacial nerve



Select Answer to see Preferred Response


The supraorbital nerve is at risk if the anterior pin is placed too medially.

When placing pins during halo immobilization a relative safe zone for anterior pin placement is located 1 cm above the orbital rim and superior to the lateral two thirds of the orbit. This prevents injury to both the supraorbital and supratrochlear nerve which are both located medially (supratrochlear nerve more medial than supraorbital nerve). Posterior pin-site locations are less critical and can be positioned on the posterolateral aspect of the skull, diagonal to the contralateral anterior pins. Pins should enter the skull perpendicular to the cortex, with the ring or crown sitting below the widest portion of the skull and passing about 1 cm above the helix of the ear.

Garfin et al. review complications associated with halo immobilization. They found pin-loosening in 36% of the patients, pin-site infection in 20%, pressure sores under either a plastic vest or a plaster cast in 11%, nerve injury in 2%, dural penetration in 1%, dysphagia in 2%, cosmetically disfiguring scars in 9%, and severe pin discomfort in 18%.

Botte at al. report superficially infected pins are managed with local pin care and oral antibiotics. Persistent or severe infections require pin replacement to a nearby site, parenteral antibiotic therapy, and incision and drainage as needed.

Illustration A shows the region of the safe zone in relation to the supraorbital nerve and supratrochlear nerve. Illustration B shows a surgical image of the supraorbital nerve. Illustration C shows the branches of the Trigeminal nerve (CN V) which include the supraorbital nerve and supratrochlear nerve.

Incorrect Answers:
Answer 2: The facial nerve (CN VII) controls the muscles of facial expression, and functions in the conveyance of taste sensations from the anterior two-thirds of the tongue and oral cavity. It is not at risk with anterior pin placement.
Answer 3: The abducens nerve (CNVI) is an intracranial nerve that is not at risk from direct damage with pin placement. Abducens nerve palsy, leading to absence of lateral gaze, is one complication of halo placement but is thought to be related to a traction injury on the nerve.
Answer 4 and 5: The zygomaticotemporal nerve and zygomaticofacial nerve are both branches of the Trigeminal nerve, but are not in the region of the medial-superior orbit.


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