A halo is a ring that is encircles the head and is fixed to it by means of pins that are inserted in the head. It is also known as “halo ring” or “halo crown,”.
This device is used in management of cervical spine diseases where spine needs external stabilization. Halo ring can be used to put traction on the cervical spine or to provide external support and immobilization. In the latter case the ring is attached to a brace that encircles patient’s torso and the whole assembly is termed as halo vest.
The concept of was first brought out in late 1950s. Before this only method to effectively restrict cervical spine mobility was traction in recumbent position.
By attaching the halo to a device worn around the patient’s torso, complications of recumbency like bed sores and chest infection can be avoided.
A ring is fixed to patient’s head by means of screws and the ring is attached to rigid, lightweight vest that fits snugly around the patient’s chest.
This way the apparatus can provides spinal stability while allowing the mobility.
Halo vest offers following advantages over the traditional traction system
- Precise positional control
- Efficient external stabilization of the cervical spine
- Low complication rate
- Minimal patient discomfort,
- Early patient mobilization.
Where Can It Be Used?
Halo vest can be used in following situations in cervical spine injuries or other pathologies that affect stability of spine
- To stabilize spine for treatment with non operative means
- In adjunct with a surgical procedure to provide additional stability
- In follow up to patients who were treated initially with skeletal traction.
How Is Halo Vest Applied
Four pins that are equally space are placed in the skull two over the ridge of the orbit and one each just behind the ear. The halo ring is fixed to these pins.
Following this vest is applied to the torso and connected with adjustable metal rods to halo ring. After the assembly is in place radiographs are taken to check position of cervical spine ad if any change need to be made.
A neurological examination is made after application of halo vest.
The duration of application varies depending upon the nature of injury and purpose for which halo vest is applied.
The assembly is well tolerated by most of the patients.
Patients are regularly followed up with series of radiographs that were performed initially to ensure adequate positioning and stabilization of the cervical spine. In addition, the physician will do a complete neurological assessment of the patient and tighten all of the hardware on the halo vest.
A neural examination is also done at the follow up visits.
Pin loosening is by far the most common of the potential complications. This happens for around 60% of patients. This can be avoided by early detection of loosening at weekly follow-up visits.
Infection at the pin sites is another complication that occurs 10-20% of patients. In case of infection of a pin tract, the pin is removed and another pin is placed in a new site.
Secondary loss of reduction may occur due to “snaking” mechanism of the cervical spine between the supine and upright positions . This phenomenon may not adversely affect the healing of upper cervical spine fractures that are inherently stable and where large cancellous bone surfaces offer a chance for relatively rapid bony consolidation.
But for this reason, however, inherently unstable fractures with small bony contact surface may not be effectively immobilized with a halo.
Halo ring and vest applications offer the most stable form of external immobilization of the upper cervical spine. In contrast to bracing, a halo vest assembly allows for some fracture manipulation and correction of malreduction. If a halo vest assembly is correctly placed, neck motion can be expected to be limited to 4% of normal flexion-extension, 4% of lateral bending, and 1% of rotation.