Cervical dystonia is a rare neurological disorder that causes involuntary contractions of the neck muscles that control head posture. Spasms cause the head and neck to bend and twist into abnormal postures that cause pain and discomfort in the neck and shoulders. Severity of symptoms can vary; however, disabling pain and dysfunctional posture often have a negative impact on quality of life. It is also referred to as spasmodic torticollis.
Definition & Facts
A type of dystonia, cervical dystonia is categorized as a focal dystonia because it is localized to one area: the neck and head. It is the most common focal dystonia. Cervical dystonia can affect people of all ages and ethnic backgrounds but is most common among individuals between 40 and 60 years old. The exact number of people living with this disorder is unknown; however, it approximately affects 60,000 people in the US and presents two times more among women than men.
Symptoms & Complaints
- Repetitive or continuous muscle spasms that pull the head into abnormal positions. Also known as clonic.
- Sustained overactivity in muscles that cause the muscle to contract and hold an abnormal posture. Also known as tonic.
Whether clonic or tonic the abnormal head postures may vary and include:
- Head rotation with chin coming toward the shoulder.
- Head tilt forward or tilt backward.
- Head tilt side with ear coming toward shoulder
- Head shift forward or backward.
The most common head posture is chin toward the shoulder. Most of the time head postures and movements are a combination of the different angles and positions.
Most cases of cervical dystonia are idiopathic, meaning the underlying cause is unknown. Although it can present with or without a family history, there is evidence that a genetic component exists due to a positive family history in 10%-25% of cases. It has also been associated with several genetic mutations including THAP1, CIZ1, ANO3. Unfortunately, genetic testing may be difficult to conduct and of limited use because genetic mutations account for such a small portion of cervical dystonia cases.
Secondary causes of cervical dystonia may include certain medications such as antipsychotics or drugs that block dopamine receptors, as well as exposure to toxins and degenerative brain disease. Physical trauma can also be a precursor; however, it is unknown whether trauma to the neck specifically may result in cervical dystonia.
Diagnosis & Tests
Currently there are no high quality diagnostic tests to confirm diagnosis of cervical dystonia. Most cases are diagnosed with a highly detailed family history, physical examination, and the knowledge, experience and insight of the clinician. Though MRIs and other imaging techniques are used to diagnose similar diseases, there are no imaging studies that help in the diagnosis of cervical dystonia. In fact, MRI scans of the brain and neck of affected individuals often show up clear without any abnormalities.
Given that there are no imaging studies or lab tests that will confirm diagnosis, a critical part of an accurate diagnosis is to rule out other conditions that present similarly. An experienced physician will be able to rule out other conditions that cervical dystonia is often misdiagnosed as, such as a strained neck from sleeping incorrectly, pulled muscles, or mental disorders.
Treatment & Therapy
Just as diagnosis will take the patience, insight, and experience of the treating physician, so will treatment. There is no standard therapy for cervical dystonia and it can be a long arduous process to find the correct method of treatment. Current treatments focus on alleviating pain, reducing overactivity of muscles, and restoring normal head posture. Three options for treatment include: Botox injections, oral medication, or surgery with or without complementary physical therapy.
Botox, botulinum toxin, is the top treatment option. The neurotoxin is injected into the affected neck muscles in small doses and causes muscle weakness due to an inhibition of the neurotransmitter, acetylcholine. When present in muscles, acetylcholine causes the muscle to contract. Botox stops the release of acetylcholine and therefore prevents muscle contractions.
Treatment begins to work about two to three days after the injection, and its effects are most prominent around week four. Botox is effective for two to six months, and when it wears off, symptoms return. There are four brands of FDA-approved botox for cervical dystonia. Each is distinct and may not be used interchangeably. For this and other reasons it is very important that the treating physician is very familiar with head and neck anatomy, and has experience dosing and administering botox for cervical dystonia. Oral medications for cervical dystonia include:
- Baclofen- Causes muscle relaxation and reduces tone in spastic muscles.
- Clonazepam (Klonopin®)- Used to treat seizure and panic disorders but causes muscles weakness.
- Anticholinergics (benztropine, trihexyphenidyl)- Acetylcholine blocker commonly used to treat generalized dystonia.
- Dopaminergic agents - Commonly used to treat Parkinson's disease and generalized dystonias by increasing dopamine levels.
Surgical treatments are the final and the last recourse for treating cervical dystonia. One surgery that has shown effectiveness is cutting the peripheral nerve of the involved dystonic muscles. Surgery is often a less attractive treatment option because access to the nerve is difficult, and finding a surgeon that is experienced in this procedure may be a challenge. Lastly, deep brain stimulation has been effective, especially in people who stop responding to botox injections.
Prevention & Prophylaxis