Post-Pump Chorea—Choreiform Movements Developing after Pulmonary Thromboendarterectomy for Chronic Pulmonary Hypertension Presenting as “Functional” Movement Disorder

The known and unknown of post-pump chorea: a case report on robust steroid responsiveness implicating occult neuroinflammation

Post-pump chorea (PPC) is characterized by the development of choreiform movements following cardiopulmonary bypass (CPB) surgery. PPC occurs almost exclusively in children, and its pathophysiology remains unclear. Here we present an adult case of PPC after bovine aortic valve replacement (AVR) which exhibited dramatic and reproducible response to steroid, suggesting the presence of occult neuroinflammation. This observation suggests a novel underlying mechanism in certain subgroups of PPC, which is likely a heterogeneous condition to start with. Further research into the pathomechanisms of PPC could offer insights into managing this otherwise symptomatic control-only condition.

Risk factors and prognosis of adult-onset post-pump chorea

OBJECTIVES

Post-pump chorea (PPC), defined as the development of chorea after major cardiac surgery utilizing cardiopulmonary bypass (CPB), has been rarely reported in adults.

METHODS

We compared 17 patients with adult-onset PPC to controls who did not develop chorea after cardiac surgery with CPB. Two patients were enrolled using hospital based data and 15 were collected by a systematic literature review. The controls without chorea after CPB (n = 4208) were collected using hospital based data. We described the clinical and surgical features of adult-onset PPC and compared them with those of the controls.

RESULTS

Ten of 17 PPC patients were male, the mean age was 46.8 years, and the mean onset latency was 6.0 days. The adult-onset PPC patients were younger (46.8 ± 16.7 vs. 59.1 ± 15.0, p = 0.001), had a lower minimum body temperature (23.3 ± 5.5 vs. 29.7 ± 3.7, p < 0.001) and a longer total circulatory arrest time (63.7 ± 7.5 vs. 21.0 ± 14.6, p < 0.001) than controls. Forty-three percentage of patients with adult-onset PPC had persistent chorea on follow-up, and these patients showed a higher rate of abnormal initial brain MRI compared with the patients with good clinical outcomes (p = 0.041).

CONCLUSIONS

The onset age, onset latency, underlying disease, treatment response, and surgical features were variable among PPC patients, while abnormal initial brain MRI was associated with persistent chorea. Pooling more cases through multicenter efforts will hopefully provide more knowledge on the underlying pathophysiology, prevention, and management of PPC.

Is postoperative encephalopathy with choreoathetosis an acquired form of neuroacanthocytosis?

Postoperative encephalopathy with choreoathetosis ("postpump chorea") is a rare complication of open-heart surgery and, in particular, the employment of a cardiopulmonary bypass pump. It almost exclusively occurs in young children. While risk factors and the underlying histopathology have been identified, the pathogenesis of postpump chorea, crucially, remains largely unknown. Transient cerebral hypoperfusion associated with cardiopulmonary bypass is considered a likely candidate mechanism, but the evidence is insufficient and inconclusive. It is hypothesized in this article, that postpump chorea may be caused by mechanical trauma to red blood cells and resulting acanthocytosis. These dysfunctional erythrocytes could then lead to damage to the globus pallidus and disease development akin to that presumed in neuroacanthocytosis. In patients with neuroacanthocytosis an association between acanthocytosis and basal ganglia pathology has been suggested. To test the mechanism hypothesized here, the effects of cardiopulmonary bypass on erythrocyte morphology and function could be systematically tested in children undergoing cardiac surgery. Ideally, the extent of erythrocyte damage could be correlated with the risk of developing postpump chorea. Finally, if the proposed hypothesis is supported by empirical findings, efforts to reduce blood cell damage during extracorporeal circulation in children might prevent this devastating complication.