Cranio-Vertebral Junction Anomalies
Dr. Ravindra Patil
on
August 18, 2023

Cranio-Vertebral Junction Anomalies
By Dr.Ravindra Patil
Anomaly
An anomaly is something that deviates from what is standard, normal, or expected. Cranio-vertebral junction anomalies mean any situation where there is some deviation from what is the ‘normal’ cranio-vertebral junction.
CVJ
The cranio-vertebral junction (CVJ) is present between the base of the skull and the upper region of the cervical spine. Any deviations or deformities in this region are known as cranio-vertebral junction anomalies. They can occur as congenital anomalies, developmental or secondary to other disease processes. Cranio-vertebral anomalies are classified into different types based on their causative factors.
The craniovertebral junction (CVJ) has unique anatomical structures that separate it from the cervical spine. In addition to housing vital nerves and blood vessels, the majority of head movements like flexion, extension, and looking sideways is accomplished at the CVJ.
The CVJ is a complex combination of osseous and ligamentous supports allow for stability despite a large degree of motion. To understand the anomalies of the CVJ, an understanding of anatomy and biomechanics in short is essential to understand the various anomalies and diseases that may affect this region.
The craniovertebral junction (CVJ) is the joint between the skull, atlas [first cervical vertebra], and axis [second cervical vertebra]. It is a complex area that houses vital nerves and blood vessels. This a joint has the most mobility as compared to any other joint of the vertebral column or the spine. The CVJ represents the transition between the brain and cervical spine. The majority of the spine’s rotation, flexion, and extension occur between the occiput, the atlas, and axis.
Table of Contents
Causes and risk factors of Cranio-vertebral Junction Anomalies
- Skeletal structure abnormalities
- Congenital systemic disorders such as Achondroplasia, Down syndrome, etc.
- Infections
- Metastatic Tumours effecting bones
- Slow growing tumours in the CVJ
- Rheumatoid Arthritis
- Traumatic injuries by an accident, a fall etc.
Signs and symptoms of Cranio-vertebral Junction Anomalies
The signs and symptoms of CVJ anomalies vary based on the cause, severity and specific structures affected. However, some common signs and symptoms may include:
- Neck pain
- Headache in the back region of the head
- Worsening head and neck pain with movement.
- Decreased range of motion in the CVJ
- Increased pain intensity while coughing or bending
Symptoms associated with spinal cord compression in the CVJ may include:
- Weakness in arms, legs or both.
- Numbness and tingling sensation on bending the neck.
- Decreased sensations of heat, cold and pain in the legs/hands/feet.
- Confusion and dizziness
Symptoms associated with brain stem dysfunction may include:
- Sleep apnoea
- Impaired balance and coordination (Ataxia)
- Involuntary eye movements (Nystagmus)
- Facial paralysis
Symptoms associated with lower cranial nerve dysfunction may include:
- Difficulty in swallowing
- Muscle weakness
- Impaired hearing
- Paralysis of soft palate and tongue atrophy
- Diagnosis of Cranio-vertebral Junction Anomalies
CVJ anomalies are diagnosed based on medical history, physical examination and diagnostic imaging scans. Lateral view X-rays, CT scan and MRI are used to visualise the structural abnormalities in the CVJ. CT scan is the most common diagnostic tool used for CVJ anomalies. However, if further investigations are required, MRI and CT myelography are considered.
Treatment of Cranio-vertebral Junction Anomalies
Surgery is the treatment of choice for CVJ anomalies. The type of surgery and approach is decided based on some factors which include: traumatic causes, non-traumatic causes, reducible or irreducible lesions. Considering these factors, the basic surgical procedures involved are reduction, immobilization, decompression and fixation. Treatment may include any one of the procedures or a combination which is determined based on the nature, severity and risk factors of the disease.
Treatments
- Full endoscopic cervical canal stenosis decompression
- Spinal fixation
- Craniovertebral junction surgeries
CVJ Fixation
Due to the complex anatomical nature as well as the significant mobility of the CVJ, fixation of this region remains at times a challenging decision and a difficult execution. A wide variety of fixation methods exist and may include a combination of the following: screws, rods, wires/cables, bone grafts, hooks, or plates. Furthermore, arthrodesis [surgical immobilization of a joint by fusion of the bones] is also a challenge as there is little space and bone surface for sufficient bone grafting.
Fixation of the CVJ to the skull can be accomplished via small burr holes and wire or a combination of screws and plates, which allows for fixation to the cervical spine through connection of rods or additional plates in the spine. Bur holes with wire are not currently used as often, as the screw/rod/plate constructs have shown to be bio-mechanically superior in terms of screw pullout strength and stiffness.
The screws used in the CVJ are generally a larger diameter than those used in the cervical spine. They have a smaller pitch and blunt tips to prevent piercing the dura mater [a thick tissue layer covering the brain and the spinal cord].
Fixation in the cervical spine can be a combination of a number of methods as well, usually with the intention of connecting to the occiput fixation. The screws used in the cervical spine are generally polyaxial and placed into the lateral masses of the vertebrae.
Generally, the skull and the first cervical vertebra [atlas] segment is not fixated alone due to the large moment arm created by the cranium on C-1. However, there are situations in which the occiput and atlas can be fixated using the above listed devices, like screws, rods, wires and so on. Sometimes a bone graft is placed in between the posterior arch of atlas and the base of the skull. Successful fusion rates of such surgeries have been reported up to 89%, but the patient’s head is not immediately stable after surgery. Such patients are required to remain in a halo neck fixation for 12 weeks.
Another option involves the use of fixing screws across joints. Similar to the above construct, this is usually reserved for isolated Skull-Atlas instability and is not easily incorporated into multisegment constructs. This technique increases stiffness in rotation but is poor in flexion-extension. Thus, this technique is used in conjunction with supplemental fixation to allow for sufficient stability.
Skull to Atlantoaxial Segment fixation
The occiput to atlantoaxial region is classically difficult to fixate as both the occipitoatlantal and atlantoaxial segments are highly mobile in flexion and extension, and additionally the atlantoaxial segment is very mobile in axial rotation. Any number of combinations of the previously mentioned techniques can be used. Occipitocervical fixation constructs consist of points of fixation along the skull, atlas vertebra and axis vertebra, with connection to some type of longitudinal element. These longitudinal elements span the segments in the CVJ and allow them to be rigidly fixated.
The above description may seem to be very complex to the lay reader. However, all efforts have been made to removed complicated medical words and use as simple words as possible.
To develop a strong CVJ construct, the longitudinal elements should be able to have multiple points of fixation along the junction, interface with all of the fixation points, have the ability to interface with the thickest regions of bone in the suboccipital region, and have the ability to be crosslinked. Various types of longitudinal elements are available and may include rods, structural bone grafts, reconstruction plates, and hybrid devices combining plates and rods in preformed shapes. As with all spinal instrumentation, it is critical to choose the type of longitudinal element that best suits the individual patient’s needs based on the goal of surgery and the patient’s anatomy.
Samarth Neuro and Multispeciality hospital in Miraj, Maharashtra, has the infrastructure and team of doctors headed by neurosurgeon Dr Ravindra Patil to accomplish such complex surgeries. Besides as the hospital is located in a tier 2 city, the overall cost of such surgeries is much less in Samarth Hospital of Miraj as compared to surgeries done in large metropolitan cities.