Antecollis, Lingual Dystonia, and Mutism Secondary to Risperidone

Ms. B. a 12-year-old female was initially brought to psychiatric unit of our hospital 3 years back for persistent learning difficulties. Her parents reported significant delay in motor development and language acquisition. Her vocabulary consisted of few words and simple sentences. She ate and took bath on her own but required mother’s help for dressing. Comprehensive assessment revealed severe mental retardation (IQ: 27). The parents were counseled about her prognosis and remedial education was suggested. Subsequent consultation took place 1 1/2 years back when she developed behavioral problems in the form of irritability, aggression and impairment of sleep. She was admitted and prescribed risperidone 2 mg/day and trihexyphenydyl 4 mg/day, with good initial improvement. She was discharged in 2 weeks after which she remained asymptomatic for 5 months. About a year back, Ms. B. experienced gradually increasing forward bending of neck which interfered with chewing and reduced her oral intake significantly. Her speech production also suffered and she became silent. Antecollis was relieved only during sleep. There was no history of high grade fever, vomiting, seizures or head and neck injury before the presenting illness. There was no history of movement disorder in the family.

During the assessment she followed simple commands but remained mute. Her neck was flexed and chin was pressed hard against the sternum. Rigidity was present only in the neck while trunk and limbs were free from rigidity, tremors, bradykinesia or other abnormal movements. Deep tendon and superficial plantar reflexes were normal. Oral examination revealed depressed tongue pressed against the base of the mouth and lower incisors; it bore indentation marks anteriorly. She was able to protrude her tongue with much difficulty. No oro-mandibular-lingual dyskinetic movements were observed. Investigations including- creatinine phosphokinase (CPK), Magnetic resonance imaging (MRI) of head and neck, electroencephalography (EEG) and cerebrospinal fluid examination (CSF) were normal. X-ray of cervical spine showed severe antecollis but was otherwise normal. Slit lamp examination of eyes did not show Keyser-Fleisher rings. Based on the above findings her condition was diagnosed as segmental cranio-cervical tardive dystonia, manifesting as severe antecollis and tongue dystonia.

After detailed discussion with her parents about diagnosis, available treatment options and on obtaining their informed consent, risperidone was slowly tapered down while clonazepam (2 mg/day) and vitamin E (400 mg/day) were added to trihexyphenydyl. Treatment with botulinum toxin was suggested but declined by the parents. Because of her chewing difficulties she was initially given semisolid diet, but as her dystonia and oral intake improved over the next 2 months solids were added. She was closely observed for emergence of behavioral problems; however, she remained well without risperidone. She was discharged after 2 months and assessed periodically. After nearly 6 months of commencement of treatment, parents reported significant improvement as she was able hold her head erect for longer periods; her tongue movements and speech output also improved substantially. Her oral intake and weight returned to her usual levels. At the time of writing this report Ms. B has been well for more than 10 months on the same treatment without any recurrence of dystonia or behavioral problems.

Tardive dystonia begins focally in the cranio-cervical region and progresses to segmental distribution; generalized involvement being quite rare.^2,6 This case illustrates at least three unusual presentations of tardive dystonia. First is antecollis, which is rarely reported and to our knowledge there is only one report where three cases of severe antecollis are described in detail.⁴ Antecollis is often reported in primary neurological illnesses like multiple system atrophy (MSA), Parkinson’s disease and progressive supranuclear palsy^7–9 but rarely as tardive phenomenon. The static nature of muscle involvement in antecollis, as opposed to hyperkinetic presentations in majority of cases of tardive dystonia, could be the reasons for its low detection.⁴

In tardive dystonia, tongue involvement typically manifests as protrusion or dyskinesias.⁵ Sustained tongue depression with mutism as manifestation of tongue dystonia has not been described till date. Mutism, in fact led us to consider catatonia as initial diagnosis; a strong possibility, seeing that the patient had mutism and rigidity. However, rigidity was not generalized and the patient lacked negativism; hence catatonia was ruled out.