What is Cranio-cervical Instability?

The first seven vertebrae are called the cervical vertebrae, which provides the "cervical" part of CCI. Vertebrae are named by the type of vertebrae (cervical, thoracic, or lumbar) and what number they are from the top. So, the fourth thoracic vertebrae is T-4; the first lumbar vertebrae is L-1. In CCI, the C-1 and C-2 vertebrae are involved, but they also have special names: C-1 is also called the atlas and C-2 is also called the axis. The atlas bone doesn't look like other vertebrae in that it is a ring that sits on top of the axis. The axis is also not shaped like a typical vertebra in that is has a bone protuberance that the atlas can sit on. This is the joint at the top of the spinal column that allows humans to nod, look side to side, and say "no" without opening their mouths. 

Image from Cleveland Clinic’s website(1) 

In people diagnosed with CCI, the ligaments in their neck that support the head are either stretched, weakened, or ruptured. This allows the atlas and axis to have more movement, because the ligaments aren't keeping them confined. It also allows the atlas and axis to compress under the weight of the head since they are bearing more of the head's weight than they are supposed to. This can cause a wide variety of issues and symptoms, as listed below.

Causes of Cranio-cervical instability

CCI is more common in people with connective tissue disorders(2), such as Ehlers-Danlos syndrome, hypermobility spectrum disorders, Marfan syndrome, osteogenesis imperfecta, rheumatoid arthritis, and lupus. In these conditions, the ligaments in the whole body may be looser, so it stands to reason that the neck ligaments may be loose as well. People diagnosed with Chiari malformation and tethered cord syndrome are more likely to have CCI as well.

CCI can also be caused by whiplash, other injuries to the head, neck, and/or spine. Any reasons the connective tissues may be damaged or stretched is a reason CCI could be present.

Symptoms of Cranio-cervical Instability

Many of these symptoms can be indicative of other conditions(2), and not all need be present for a diagnosis of CCI.

In the image below, there are arteries, a major vein, and a major nerve that run right by the atlas and axis. If C1 and C2 bones aren't being held in the correct place due to lax ligaments, the bones could potentially lean on the other structures, causing some of the symptoms below.

Image from Caring Medical’s website(3) 

Head-related Symptoms

• Debilitating, heavy headache--near constant in the lower back of the head; possibly migraine headaches

• Head feels like it weighs too much to hold up; feeling "bobble-headed" and like the head may "fall off the spine"

• Pressure headache--potentially caused by blocked cerebrospinal fluid, aggravated by things like sneezing, coughing, yawning, laughing, crying, etc. Also called intercranial hypertension.

• Facial numbness

• Tenderness or pain at the base of the skull, especially with flexion or rotation

• Sinus problems

Neck-related Symptoms

• Reduced range of motion of the neck

• Central or mixed sleep apnea

• Neck pain

• Difficulty swallowing or the feeling of being choked

Mouth-related Symptoms

• Mouth or jaw pain, including temporomandibular joint pain (TMJ)

• A reduced gag reflex

Musculoskeletal-related Issues

• Shoulder pain

• Electrical "zings" down the back and into the limbs when bending the head forward (also known as Lhermitte’s sign)

• Tremors

• Paralysis

• Myalgic encephalomyelitis/chronic fatigue syndrome

Nervous System-related Symptoms

• Dysautonomia(4)

• Issues with balance and dizziness

• Heart palpitations

• Shortness of breath

• Weak muscles, especially in the limbs

• Fatigue

• Fainting

• Brain fog

• Insomnia

• Hiccups

• Inability to maintain consistent body and skin temperature

• Excessive sweating

• Itching skin

• Tremors

• Paralysis

Eye-related Symptoms

• Pain in or behind the eyes

• Problems with vision, including blurred and double vision

• Intense sensitivity to light (photophobia)

• Irregular eye movement

• Changes in peripheral vision

• Blindness in one eye that comes and goes

Ear-related Symptoms

• Tinnitus

• Nausea

• Ear fullness or hearing problems

• Meniere’s disease (a build-up of fluid in the inner ear that includes hearing loss, tinnitus, vertigo, anxiety, and nausea)

• Red ear syndrome

Mental Health-related Symptoms

• Anxiety

• Depression

• Dissociation

• Emotional stress

• Cognitive and memory decline

• Insomnia

Other Symptoms

• Vomiting

• Clumsiness and motor delay

• Decreased blood flow in and out of the brain

• Cervical angina

• Oscillopsia (the feeling that your environment is moving around you)

• Empty nose syndrome (trouble emptying the nose or breathing even though the nose is wide open, usually a result of nasal surgery)

Diagnosis of and Treatments for Cranio-Cervical Instability

CCI is diagnosed by a medical profession, usually a neurologist. In addition to learning about symptoms, observing signs, and looking into a patient's medical history, a magnetic resonance image (MRI) is usually obtained. Many neurosurgeons prefer the MRI be taken while the patient is standing to see the laxity and compression which isn’t as visible when a patient is lying down.(4) Upright MRIs are not available at every medical center, so performing standard MRIs of the patient in neck flexion, neck extension, and neck neutral positions is able to show radiologists and neurologist what they need to see.

Other diagnostic tests for CCI include computer tomography (CT) scans, dynamic X-ray or CT, myelography with CT scan, and CT angiography.(5)

Treatment for CCI is initially conservative, focusing on pain management, physical therapy, rest, and cervical collars. Some providers will recommend chiropractic care, prolotherapy, or stem cell therapy, but discussion with medical providers can help weigh the benefits and risks.

If conservative management isn't helpful, surgical options exist, though there haven't been many long-term studies about how well patients do after. There may be relief of some symptoms, worsening of others, or no effect at all. The surgery most often used to help with CCI is called an occipito-cervical fusion. The surgery fuses the skull to the spine to stabilize it. Titanium screws and rods as well as a bone graft (from the patient's rib, made synthetically, or from a cadaver) are used to create the fusion. As with all conditions, patients, their families, and their doctors should create a treatment plan that fits well with the patient's symptoms, goals, and lifestyle.

1.     https://my.clevelandclinic.org/health/articles/22278-cervical-spine

2.     https://en.wikipedia.org/wiki/Craniocervical_instability

3.     https://caringmedical.com/prolotherapy-news/craniocervical-instability/

4.     https://www.uprightmrideerfield.com/what-is-cranio-cervical-instability-and-how-is-it-detected

5.     https://neurosurgery.weillcornell.org/condition/craniocervical-junction-disorders/diagnosing-and-treating-craniocervical-disorders