Is the Relationship Between Paroxysmal Kinesigenic Dyskinesia and Choroidal Fissure Cyst: a Coincidence or Cause and Effect?

Abstract

Background & Significance: Paroxysmal kinesigenic dyskinesia (PKD) is diagnosed on the basis of the clinical characteristics. These include identified trigger for attacks, short duration of attacks, lack of loss of consciousness or pain during attacks, antiepileptic drug responsiveness, exclusion of other organic disease, and age of onset between 1 and 20 years if there is no family history. PKD is divided into idiopathic or secondary cases. The underlying etiology for secondary cases comprises demyelinating lesions, vascular lesions, metabolic derangement, or trauma. To our knowledge, an association with choroidal fissure cysts has not yet been reported. We present a patient with PKD who had a choroidal fissure cyst in the temporal horn.

Case: A 16-year-old man visited the hospital because he experienced episodic involuntary movements. The first episode occurred three year ago, when he developed dystonic posture on initiation of standing or running. Dystonia started on the right side, which progressed to involve the whole body within a few seconds, with his face and body eventually becoming severely twisted. During the attack, there was no loss of consciousness. The patient had no specific family history. Neurological examination was unremarkable. He was responsive to carbamazepine. Brain magnetic resonance imaging (MRI) disclosed a choroidal fissure cyst in the left temporal horn. Brain perfusion SPECT and electroencephalogram (EEG) were all normal.

Conclusions or Commentes: The pathomechanism of PKD is unclear, although channelopathy, dysfunction of basal ganglia, or epileptic phenomenon have been suggested as possibilities. Considering that PKD associates with epilepsy in terms of presence of aura, family history of epilepsy, and responsiveness to antiepileptic drug, we could not rule out the possibility of its association with the finding of a choroidal fissure cyst compressing the hippocampus. The patient did not undergo surgery because of the good outcome of PKD and benign nature of the choroidal fissure cyst. Although we could not approve the direct relationship between the choroidal fissure cyst and PKD, it is interesting that this patient with PKD had a cyst with a specific location in the temporal region.