Natural History, Neuroradiological Workup, and Management Options of Chronic Atlantoaxial Rotatory Fixation Caused by Drug-Induced Cervical Dystonia

Atlantoaxial rotatory fixation (AARF) resulting from drug-induced cervical dystonia (DICD) represents an extremely rare complication of antipsychotic treatment, requiring a comprehensive assessment of pharmacologic therapy and timely radiologic workup. We report a chronic case of Fielding type I, Pang type I AARF secondary to schizophrenia treatment in a 16-year-old girl, along with a review of the literature on the management challenges posed in this condition. In this scenario, torticollis may just represent the tip of the iceberg, and only an effective multidisciplinary approach increases the chances of satisfactory correction with closed reduction, hence avoiding the burden of more invasive treatment options.


Introduction
The rotatory subluxation of the atlantoaxial joint, also known as atlantoaxial rotatory fixation (AARF), is a frequent cause of torticollis in children [1], which was firstly reported by Corner in 1907 [2]. A thorough clinical description of this condition was provided by Wortzman and Dewar in 1968 [3]; nonetheless, the term AARF was introduced only by Fielding and Hawkins who also classified AARF into 4 types (Table 1) in 1977 [4]. Over the years, this condition has been described as atlantoaxial rotatory subluxation [3,5,6], dislocation [7], or displacement [8], making the pertinent literature fairly heterogeneous until the seminal work from Pang led to the introduction and diffusion of a more modern classification and management algorithm (Table 1) [9].
Patients with AARF present with neck pain, limited neck motion, and the so-called cock-robin posture, where the head is rotated to one side and on lateral flexion con-tralaterally ( Figure 1(a)); the most common causes are trauma and infection, rheumatoid arthritis, head and neck surgery, and congenital connective disorders [10,11].
Rarely, cervical dystonia has been linked to AARF [12][13][14]. Although it is known that antipsychotics sometimes induce cervical dystonia [15,16], there have been no reports of AARF caused by drug-induced cervical dystonia (DICD). We report such a rare presentation during schizophrenia treatment, enriched by a review of the literature.

Case Report
2.1. Clinical History. A 16-year-old girl with recent diagnosis of schizophrenia was prescribed treatment with antipsychotics. After few months, she started to have neck pain and torticollis and two years later was diagnosed with antipsychotic-related tardive DICD. An antiparkinsonian agent was started, and botulinum toxin was injected twice, yielding minimal improvement. After a year of unsuccessful treatment, she was hospitalized for further treatment and was referred to our department for evaluation of the torticollis.

Examination and Diagnostic
Workup. Due to the uncontrolled schizophrenia, she had delusions, hallucinations, and disorganized thinking and behaviors. Although communication was very difficult, the patient was identified to be suffering from persistent neck pain and difficulties with eating, swallowing, and gaze. She was fixed in a typical cock-robin posture; the neck was twisted to the right and flexed to the left (Figure 1(a)). She had no neurological deficits.

Treatment Course.
Considering her mental condition, continuous traction, halo vest, and surgical intervention were not deemed appropriate in the first instance, due to safety concerns. She was mentally unstable and had a risk of taking unpredictable movements; hence, the consensus from multidisciplinary team (MDT) discussion was to perform only closed manual reduction followed by immobilization with the Philadelphia collar. Closed manual reduction was conducted under general anesthesia and fluoroscopy (Arcadis Orbic 3D, Siemens Healthineers) in the operation room. Neck alignment appeared normalized in the neutral position (Figure 2(a)), and reposition of the atlas was confirmed with fluoroscopy (Figures 2(b) and 2(c)). The patient was placed in a Philadelphia collar fixation immediately.

Outcome.
Unfortunately, few days later, torticollis recurred despite good compliance with the Philadelphia collar. The atlas was rotated 45 degrees to the right from the neutral position ( Figure 3). The strategy adopted included an immediate attempt to achieve reduction again under general anesthesia; nonetheless, this also led to an iatrogenic fracture of C2 lateral mass (Figure 4(a)) and atlantoaxial rotatory subluxation remained (Figures 4(b) and 4(c)). Family discussion was held, and surgical option to minimize the chances of recurrence or pseudoarthrosis was abandoned given the high perioperative risks. The final decision was therefore to continue conservative treatment with the Philadelphia collar and carry out a close clinical and radiological monitoring. Bony union was obtained 2 months later ( Figure 5), and during follow-up, the patient demonstrated a consistent improvement of neck pain, range of neck motion, and activities of daily living (ADL); therefore, no further spinal treatment was needed. Five months after the fracture, range of neck motion had improved to 60 degrees, which was considered to be a good result, given that the C1-C2 joint was already completely "locked" before treatments.

Discussion
There have been no previous reports of AARF with druginduced cervical dystonia. Tardive dystonia is known as one of the side effects of antipsychotics, and the most frequent type is cervical dystonia [16,18]. The first choice of treatments of cervical dystonia is oral medications such as trihexyphenidyl, benzodiazepines, or tetrabenazine. Other choices are botulinum injection and deep brain stimulation [19][20][21][22]. Although the mechanisms underlying AARF in patients with cervical dystonia are not clearly understood, it is assumed that the contraction of the sternocleidomastoid muscle causes rotatory subluxation of the atlas and the axis.
Pang's classification, which further groups patients into acute, subacute, and chronic, is particularly useful to guide the treatment strategy. Whereas acute (<1 month) and subacute (>1-<3 months) AARF can usually be treated by nonoperative treatment such as closed manipulation or cervical traction followed by bracing [10,23], the treatment strategy for chronic AARF (lasting >3 months) is controversial. Halter traction and skull caliper traction are recommended as the initial treatment in the algorithm by Pang and Li [23]. Ishii et al. reported that closed manipulation followed by halo fixation is an effective treatment. Surgical treatments are recommended for cases with C1-2 bony union, irreducible or recurrent subluxation, and Fielding type 4 [10]. Treatment options of AARF are shown in Table 2 [10,[24][25][26][27][28].
The complexity of treating patients with uncontrolled schizophrenia relates to their tendency toward unpredictable movements and higher rates of postoperative complications [29,30]. Any invasive treatments, such as traction and surgery, are therefore not recommended. When treating this challenging category of patients, it is important to ensure a comprehensive diagnostic workup and start    Case Reports in Orthopedics closed reduction at an early stage, before traction, halo fixation, or surgery becomes a necessary step. Optimization of medical treatment and immobilization in the hard collar may prove safer and relatively effective; nonetheless, a close clinical and radiological monitoring is recommended due to the inherently high risk of failure.

Conclusion
AARF resulting from DICD is a rare complication of antipsychotic treatment, requiring a comprehensive assessment of pharmacologic therapy and timely radiologic workup. In this scenario, torticollis may just represent the tip of the iceberg, and only an effective multidisciplinary management can increase the chances of a satisfactory correction with closed reduction, hence avoiding the burden of more invasive treatment options.

Consent
The patient and her parents were informed that the data from the case would be submitted for publication and gave their consent.