Review Question - QID 216421

In this patient with involuntary episodes of neck movement exacerbated by voluntary action, head tremors, headache, neck pain, and a family history of movement disorders, cervical dystonia is the most likely diagnosis. Dysfunction of components of the basal ganglia such as the striatum has been implicated in the pathophysiology of this disease.

Dystonia is a spectrum of neurologic disorders that present with involuntary movements or postures due to intermittent muscle contractions. This condition is often worsened by voluntary action and may be associated with an inconsistent tremor. Although dystonia was classically believed to be due to disruption in the basal ganglia, more recent evidence suggests that dystonia is a disease that involves perturbations of a circuit comprising the basal ganglia, cerebellum, thalamus, and cortex. Abnormalities in temporal and sensory discrimination, cerebellar feedback, dopaminergic processing, and calcium signaling in the basal ganglia may all contribute to this disease. Some dystonias of a single muscle group (isolated dystonias) are associated with monogenetic lesions. For example, mutations in GNAL can lead to a deficit in dopaminergic signaling in the striatum which can lead to cervical dystonia with autosomal dominant inheritance. Treatment for cervical dystonia includes a trial of levodopa and botulinum toxin injections.

Balint et al. provide a review of the pathophysiology, clinical presentation, and treatment of dystonias with a focus on isolated dystonias. Figure 1 provides a historical perspective of this disease, including the recognition of this disease as an organic, not a psychiatric disorder. Figure 4 provides a useful summary of the pathophysiology of dystonia, including the role of dystonia-associated genes such as GNAL. The authors recommend the use of anticholinergics, intramuscular botulinum toxin injection, and deep brain stimulation to help treat dystonias.

Incorrect Answers:
Answer 1: Atlantoaxial subluxation is a misalignment of C1 and C2 which can mimic dystonia and present with neck pain, headache, and intermittent spinal cord compression. This disease can occur from major trauma or in patients with rheumatologic disorders. In this otherwise healthy patient with episodes of involuntary movement and no history of trauma, dystonia due to basal ganglia dysfunction is more likely.

Answer 2: Autoimmune response to Group A Streptococcus (GAS) infection in children can cause Sydenham chorea. This presents with rapid, involuntary, dance-like jerking movements affecting both the face and extremities between 1 week and 6 months after acute GAS infection. Adult-onset Sydenham chorea is very rare. In this 37-year-old patient with no childhood history of Sydenham chorea, dystonia due to basal ganglia dysfunction is more likely.

Answer 3: Congenital shortening of the sternocleidomastoid is the hallmark of congenital muscular torticollis, a disease that presents in infants or young children with an ipsilateral head tilt. The etiology of this disorder is poorly understood but may be related to intrauterine positioning. This disease usually presents with restricted head movement and ipsilateral head tilt, and would not present with the new onset of abnormal movement in an adult patient.

Answer 5: Functional movement disorders (FMD) are mimics of true dystonias characterized by involuntary movements incongruous with known neurologic causes. Although not pathognomonic, features that suggest a FMD include a previous history of somatization, inconsistent dystonic movements, dystonia at rest, and pain as a prominent aspect. In this patient with a family history of movement disorders, dystonia worsened by movement, and no previous psychiatric history, true dystonia due to basal ganglia dysfunction is more likely.

Bullet Summary:
Dystonia is a movement disorder characterized by abnormal muscle contractions and is associated with dysfunction of the basal ganglia.