Cervical dystonia (CD) is a neurological movement disorder characterized by involuntary contractions of the neck muscles, which cause the head to twist, tilt, or pull into abnormal postures. The diagnosis of CD is primarily clinical, relying heavily on the detailed observations and expertise of a physician, particularly a movement disorder specialist. There is no single blood test or scan that can definitively confirm CD; instead, the process involves a careful review of symptoms and the systematic exclusion of other conditions.
Initial Clinical Evaluation and Symptom Review
The diagnostic process begins with a detailed medical history. The physician focuses on documenting the exact nature of the involuntary movements, including their onset, frequency, and severity. Patients often describe symptoms such as head pulling, twisting (torticollis), tilting (laterocollis), forward flexion (anterocollis), or backward extension (retrocollis).
A comprehensive history also includes questions about a family history of dystonia or tremors, as some forms of the disorder can be inherited. Physicians review all current and past medications, as certain drugs, particularly dopamine-blocking agents, can induce secondary dystonia. The patient’s description of when the movements occur—intermittent, constant, or only during specific activities—helps frame the diagnosis.
The Neurological and Physical Examination
The hands-on assessment identifies the physical hallmarks of cervical dystonia. This examination involves observing the head and neck posture while the patient is at rest, walking, and performing specific tasks. The physician looks for specific patterns of muscle contraction, such as the enlargement or hypertrophy of overactive neck muscles.
A highly characteristic finding is the “geste antagoniste,” often called a sensory trick. This is a simple, voluntary maneuver, such as lightly touching the chin, cheek, or the back of the head, that temporarily reduces the involuntary muscle contractions. The presence of this sensory trick strongly suggests a diagnosis of dystonia, as it is not typically seen in other movement disorders. The examination also assesses the severity of the abnormal head position and the presence of an associated tremor.
Imaging and Laboratory Tests to Exclude Mimics
While the diagnosis of primary cervical dystonia is clinical, various tests are performed not to confirm the condition, but to rule out secondary causes that can mimic its symptoms. These structural or acquired conditions are often referred to as “mimics” and must be excluded before a diagnosis of primary CD is finalized. Structural issues, such as tumors, strokes, or lesions in the brain’s basal ganglia, can cause secondary dystonia, making neuroimaging necessary.
Magnetic Resonance Imaging (MRI) or Computed Tomography (CT) scans of the brain and cervical spine are commonly used to check for these structural abnormalities. Additionally, laboratory tests, including blood and urine analyses, are conducted to exclude underlying systemic causes. These tests screen for metabolic disorders, such as Wilson’s disease, or the presence of specific toxins or infections that can induce a secondary form of dystonia. The goal of this phase is strictly one of exclusion.
Finalizing the Diagnosis
After a thorough clinical evaluation and exclusion of secondary causes, the diagnosis is confirmed by a neurologist, typically a movement disorder specialist. This specialist utilizes the collected clinical data to definitively classify the condition as cervical dystonia.
To provide an objective measure of the disorder’s impact, the physician may use standardized rating scales, such as the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS). This scale documents the severity of the dystonia, the degree of disability, and the associated pain, helping to track progression. Although not required for diagnosis, electromyography (EMG) may be used to confirm which specific neck muscles are overactive, which is useful for guiding subsequent treatment with botulinum toxin injections. Confirmation of the diagnosis allows the medical team to develop a tailored treatment strategy.