Abstract

Background

Cervical dystonia (CD), or spasmodic torticollis, is a hyperkinetic movement disorder characterised by sustained, involuntary muscle contractions involving the cervical muscles. It presents as repetitive twisting or tilting of the neck and is the most common form of dystonia. The etiology of secondary CD is diverse and includes drug-induced dystonia, trauma, Parkinson’s and Wilson’s disease, though many cases are ultimately labelled as idiopathic. Lesions in the basal ganglia and thalamus have been classically implicated, though recent studies have shifted the focus to the cerebellum, brainstem, and the cerebello-thalamo-cortical circuit.

While pontine pathologies have been documented as causes of generalised or segmental dystonia, isolated focal CD linked to a discrete pontine insult is exceedingly rare. We report a striking case of isolated CD as the presenting feature of central pontine haemorrhage.

Case Presentation

A 48-year-old female with no known comorbidities presented with episodic, involuntary rightward head nodding and twisting for one week. Examination revealed involuntary contractions of the right sternocleidomastoid and left splenius capitis, consistent with focal CD. Notably, there were no cerebellar signs, brainstem deficits, or other localising signs. MRI identified a subacute hematoma and microhemorrhages confined to the central pons, with features suggestive of pontine capillary telangiectasias. Symptomatic treatment with low-dose trihexyphenidyl, baclofen, and clonazepam was begun. The patient experienced near-complete resolution of symptoms within two weeks.

Discussion

Recent studies have implicated the cerebellum and brainstem in dystonia. The olivocerebellar pathway, reticulospinal tract, pedunculopontine nucleus, and dentate-rubro-olivary pathways have been considered. Most existing reports highlight generalised or hemidystonia following pontine pathologies. One series of four patients reported tegmental pontomesencephalic hemorrhage in three cases—all had hemidystonia. Another case described torticollis after radiosurgery, with necrosis across the pons and cerebellum. In our case, CD was the presenting feature that led to unravelling the diagnosis. The temporal association suggests, though does not prove, causality.

Treatment

A number of therapeutic options are available for focal and generalised dystonia. Botulinum toxin remains the mainstay. Clonazepam, trihexyphenidyl, and baclofen were effective in our patient, avoiding escalation to invasive interventions. Reports on hemidystonia following pontine lesions also show improvement with oral medications. Pallidal DBS is effective but reserved for refractory cases. A pooled meta-analysis noted that both GPi and STN were equally effective targets. Literature guiding therapeutic decisions in this cohort remains sparse, justifying further studies.

Conclusions

This case highlights isolated cervical dystonia as a rare presenting feature of pontine hemorrhage and reinforces the pons’ role in the pathomechanism of dystonia. Treatment options, though limited, are often effective.