Interictal crossed cerebellar hyperperfusion on Tc-99m ECD SPECT

Area of Science:

• Neurology
• Nuclear Medicine
• Neuroimaging

Background:

• Crossed cerebellar hyperperfusion (CCH) is a rare phenomenon typically observed during ictal states in epilepsy patients using cerebral perfusion SPECT.
• The proposed mechanism involves remote effects via the corticopontocerebellar pathway (CPCP), leading to contralateral cerebellar hemisphere hyperperfusion secondary to unilateral supratentorial epileptic foci.
• This pathophysiology is analogous to crossed cerebellar diaschisis (CCD).

Observation:

• This report details the first documented instance of interictal CCH.
• The observation was made in a patient with epilepsy utilizing technetium-99m-ethyl cysteinate dimer (Tc-99m ECD) brain SPECT imaging.
• The CCH was identified during the interictal period, not during a seizure.

Findings:

• Demonstration of interictal crossed cerebellar hyperperfusion (CCH) in an epilepsy patient.
• Successful visualization of CCH using technetium-99m-ethyl cysteinate dimer (Tc-99m ECD) SPECT.
• This represents the first reported case of interictal CCH in the medical literature.

Implications:

• Expands the understanding of CCH beyond ictal states in epilepsy.
• Suggests that Tc-99m ECD SPECT may reveal CCH even when patients are not actively seizing.
• Highlights the potential for detecting remote cerebellar effects in epilepsy using specific neuroimaging techniques during interictal periods.