Cervical Dystonia Mimics: A Case Series and Review of the Literature

Case 1

A 48-year-old gentleman presented with a 2.5-year history of abnormal posturing of the neck. The symptoms started gradually, reaching a peak at around 5 months after onset. He was diagnosed with cervical dystonia and was treated with an anticholinergic, dopa agonists, and benzodiazepines without any benefit. During this course, he underwent repetitive nerve stimulation and magnetic resonance imaging (MRI) of brain, which was normal. An MRI of the cervical spine showed degenerative disc changes without any significant compression of nerve roots or cord changes. Due to persistent symptoms and impaired activities of daily living, he was referred for botulinum toxin injections. There was no significant family history or history of exposure to antipsychotics. He had anterocollis and intermittent lower facial contractions. Passive range of movements of the neck was within normal limits. Power assessment revealed severe neck extensor weakness (Grade 0–1/5 Medical Research Council (MRC)) (Video 1). There were no other associated findings.

Further evaluation showed normal serum creatinine phosphokinase (CPK) (162 IU/dl). An MRI of the cervical muscles showed atrophy, fatty infiltration, and fibrosis of deep cervical muscles, especially at the level of C2, extending above and below. Trapezius and sternocleidomastoid muscles appeared normal (Figure 1A). Electromyogram of the Trapezius and Semispinalis showed very few motor unit potentials (MUP) and no recruitment. Bilateral sternocleidomastoid showed increased spontaneous activity (right > left), with normal recruitment. Clinically, he was considered to have head drop secondary to isolated neck extensor weakness (INEM), mimicking cervical dystonia.

Figure 1

Case 2

The 22-year-old man presented with a history of abnormal neck posture since early childhood. He was evaluated and diagnosed with cervical dystonia and treated with botulinum toxin injections. Due to limited clinical benefit, he was referred to our clinic. On evaluation, he was noted to have torticollis to the right with mild retrocollis (Video 2). In addition, he was also noted to have a thin and taut left sternocleidomastoid muscle. An MRI of the neck showed atrophy and fibrosis of the left sternocleidomastoid (Figure 1B) along with scoliosis of the cervical spine with convexity to the right side. He was diagnosed with developmental sternocleidomastoid fibrosis mimicking cervical dystonia, and a surgical release was suggested.

(1) Vascular

A number of vascular pathologies can result in true cervical dystonia, majority of them being ischemic or hemorrhagic events of the brainstem, cerebrum, and cerebellum.^2–5 However, vascular anomalies are noted to have abnormal neck posturing due to compensatory mechanisms to aid visual defects.⁶ Other vascular causes like aneurysms and arteriovenous malformations (AVM) can also result in dystonia.^6–9 An abnormal neck posture can also be seen as a compensatory mechanism to overcome visual field defects masquerading as cervical dystonia.⁶ Spinal epidural hemorrhage secondary to severe hemophilia can present with torticollis.¹⁰ The outcomes are variable, but spontaneous improvement is reported in almost half of the cases.^2–10

(2) Musculoskeletal

Any anatomical/physiological variations in the cervical musculoskeletal system can present with cervical pseudodystonia. In our series, the possible cause for incorrect diagnosis of cervical dystonia in INEM was additional movements of the facial and neck muscles in an effort to lift the head, giving rise to the interpretation of neck drop as anterocollis. Clinical assessment for muscle strength was the key clinical feature in the diagnosis. Every patient should be evaluated to rule out secondary causes. INEM mimicking cervical dystonia is a rare condition and can pose a diagnostic dilemma. This condition is also known as “dropped head syndrome,” which has a wide spectrum of causes.¹¹ Routine blood, electrophysiological, radiological, and histological investigations help in confirming isolated myopathy. Some of these causes are potentially treatable, including myasthenia, hypothyroidism, hyperparathyroidism, hypokalemia, etc. Management of INEM involves physiotherapy, orthotic collars or braces, and rarely surgical fixation.¹²

Congenital muscular torticollis is another common musculoskeletal cause of cervical pseudodystonia. It is commonly diagnosed during infancy and is caused due to intrauterine malposition or birth trauma. On palpation, the sternocleidomastoid muscle is taut and non-tender. Absence of tremor and sensory trick makes cervical dystonia less likely (see Case 2). There is a restriction in the range of movements of the neck. Some cases resolve spontaneously, while most of them respond well to physical therapy. Physical therapy involves passive stretching and encouraging active movements. Less than 10% of cases require surgery. Early treatment remains the key for better outcomes.^13–15

Various craniocervical developmental anomalies can also present with cervical pseudodystonia. Klippel–Feil syndrome is a congenital anomaly caused by the fusion of a pair or more of cervical vertebrae. It is characterized by a short neck, torticollis, limited range of movements and low posterior hairline. Symptoms become more pronounced during adolescence or young adulthood. Vertigo, tinnitus, and hearing loss are sometimes associated with this condition. It can masquerade as cervical dystonia, which becomes apparent after radiological evaluation. Treatment is mostly symptomatic. Surgery may be needed if associated with scoliosis, radiculopathy, or myelopathy. Pseudodystonic posture secondary to Klippel–feil syndrome and diastometamyelia has been reported.¹⁶ Other CVJ anomalies like Chiari malformation and basilar invagination are known to cause torticollis.^17–18 Syringomyelia associated with torticollis is a rare presentation. It requires a high degree of suspicion when head tilt is seen along with sensory loss. Dystonic movements of the rest of the body can also be seen occasionally. An MRI of the spine can confirm the diagnosis. Decompression of the syrinx relieves the symptoms.¹⁹

Acute, painful torticollis in children with a history of fall or trauma points toward atlantoaxial rotatory subluxation (AARS).^20–22 It can also be due to a local inflammatory process, or connective tissue disorders. A rare case of AARS was seen associated with familial Mediterranean fever (FMF) presenting with torticollis.²³ FMF is an autosomal recessive autoinflammatory condition, presenting with episodes of fever and serositis. Cervical dystonia in ankylosing spondylitis resulting in AARS and craniocervical osseous fusion (CCOF) has been reported.²⁴ If there is no history of trauma, it is important to look for a history of recent ENT surgeries or any inflammatory conditions of the neck, as it could be Grisel’s syndrome, which is a non-traumatic atlantoaxial subluxation resulting from an ongoing local inflammatory process.^25–27 Grisel’s syndrome is more commonly seen in children due to laxity of ligaments along with the tenderness of the spinous process, and there may be unilateral occipital pain. A spinal cord injury should be suspected if there are associated neurological symptoms such as unsteady gait or hyperreflexia.²⁵ Early diagnosis and management is the key. It is usually treated by manipulation under anesthesia and immobilization. For less severe cases, cervical soft collar with rest and analgesia may be sufficient. Delay in the diagnosis can lead to neurological complications and require surgery.^28–30

Other causes like intervertebral disc calcification, acute calcific tendinitis of longus colli, facetal hypertrophy, and nodular fasciitis of sternocleidomastoid should be considered in the differential diagnosis of musculoskeletal causes of pseudodystonia.^31–34

(3) Infections

Infections of the upper respiratory tract or soft tissues of the neck can cause torticollis to mimic cervical dystonia. These include cervical adenitis, lymphadenitis, retropharyngeal abscess, and sternocleidomastoid myositis.^35,36 Retropharyngeal abscess is a serious condition presenting with severe pain, fever, and difficulty in breathing and swallowing along with torticollis. It requires immediate treatment with antibiotics, non-steroidal anti-inflammatory drugs (NSAIDs), and sometimes surgical drainage of the abscess. Similarly, paravertebral brucellar abscess and sternocleidomastoid abscess are documented to present as cervical pseudodystonia.³⁷

Other reported causes of atypical infections presenting with cervical pseudodystonias include cat scratch disease, encephalomyelitis, bacterial meningitis, neuroborreliosis, tuberculoma, tuberculosis of the bone and joints, septic arthritis, spondylodiscitis, and osteomyelitis.^38–46

(4) Mass lesions/space occupying lesions

Central nervous system lesions can also cause cervical pseudodystonia, along with symptoms like nausea, vomiting, headache, ataxia, visual disturbances, and cranial nerve deficits. These lesions include posterior fossa and infratentorial tumors (more commonly in the cerebellum, third ventricle, and brainstem) and spinal cord tumors like astrocytomas, medulloblastomas, and ependymomas.^7,35,47,48 Cervical osteoblastoma, hemangioblastoma, osteochondroma, osteoid osteoma, fibrodysplasia ossificans progressiva, giant cell tumor, and Ewings sarcoma can all present with torticollis.^7,49–54 Torticollis in children requires brain and spinal cord imaging to avoid delay in diagnosis, which can be life threatening. Surgical removal of the tumor in most cases results in resolution of the symptoms.

Cervical pseudodystonia has been described in carcinoma larynx (following radiation therapy) due to fibrosis of neck muscles and in a Pancoast tumor of the lung due to possible segmental demyelination of the 11th cranial nerve.^55,56

(5) Traumatic

Trauma resulting in odontoid fracture, laminar fracture, condylar fracture, osteoporotic fracture, C1 dislocation with split atlas due to various causes can all present as dystonia mimics.^57–61 Appropriate management will alleviate symptoms.

Other traumatic conditions presenting with a similar picture include brachial plexus injury, pneumomediastinum, foreign body, and rarely electrical injury.^62–65

(6) Ocular causes

Ocular causes like congenital nystagmus, nystagmus compensation (blockage) syndrome, spasmus nutans, oculomotor apraxia, refractive error, blepharoptosis, superior oblique palsy, abducens palsy, vertically incomitant horizontal strabismus, Duane syndrome, Brown’s syndrome, double elevator palsy, orbital floor fracture, endocrine ophthalmopathy, congenital fibrosis syndrome, and inferior oblique muscle palsy may present with torticollis called ocular torticollis. Abnormal head position is assumed in order to maintain binocularity and/or to optimize visual acuity. Bielschowsky head tilt test is the primary test in the ocular torticollis workup. Treatment is usually surgical and depends on the underlying cause.⁶⁶

(7) Otological causes

Cervical pseudodystonias secondary to vestibular dysfunctions Contribute to otological causes. These patients have ataxia, vertigo, or nystagmus along with torticollis. Acute mastoiditis, saccular dysfunction, and Bezold’s abscess are few examples. This requires further assessment of the vestibular system and management.^67–69

(8) Gastrointestinal causes

In a child presenting with torticollis or side-to-side head movements associated with vomiting, regurgitation, or epigastric pain, Sandifer’s syndrome can be suspected. The symptoms can be intermittent and are associated with meals in most cases. The symptoms are probably due to the patient assuming a position to minimize the painful acid reflux. As the early symptoms resemble dystonia, evaluation is focused on neurological etiology, which is usually normal. Diagnosis is by monitoring esophageal pH and demonstrating reflux. Medical treatment for gastroesophageal reflux usually resolves the symptoms, but sometimes this condition requires surgery.^70,71

(9) Psychogenic dystonias

Psychogenic dystonia, also known as functional dystonia, is a controversial diagnosis commonly associated with psychiatric comorbidities like anxiety, depression, and personality disorders. Variability of symptoms suggests a psychogenic cause. The current classification has suggested categorization of psychogenic dystonias as one of the acquired dystonias.¹ Although prognosis can be poor with long-term disability, mainstay of management involves communicating the diagnosis with the patient, physiotherapy, and behavioral therapy.^72,73

(10) Others

There are various other causes of cervical pseudodystonias, which are either rarely reported or documented as single association. Among these, benign paroxysmal torticollis (BPT) of infancy is a self-limiting condition, characterized by periods of unusual, sustained posture of the head and neck, during which the head tilts to one side. Episodes are often accompanied by marked autonomic features, irritability, ataxia, apathy, and drowsiness. They last several hours to a few days and often recur every few weeks. They subside within the pre-school years. It is essential to recognize this condition and to reassure parents of its benign course and not to be misdiagnosed for other disorders, such as epileptic seizures. BPT of infancy has been linked to CACNA1A mutations and are likely to be associated with familial hemiplegic migraine, episodic ataxia, and paroxysmal tonic upgaze.^74,75 There is no approved medication for the disease. Some studies have demonstrated the uses of cyproheptadine and topiramate for BPT.⁷⁶

Other rare neurological causes presenting as cervical pseudodystonia include idiopathic intracranial hypertension, acute demyelinating encephalomyelitis, multiple sclerosis, Guillain–Barre syndrome, hypereosinophilic syndrome, widespread nevus spilus, Parry–Romberg syndrome, moyamoya disease, atypical Kawasaki disease, Behcet’s disease, Langerhans cell histiocytosis, Goldenhar syndrome, Goeminne syndrome, iatrogenic hypoparathyroidism, and allergy.^77–92 These conditions have been reported in isolated case reports.