Assertion: nightmare's cause | /r/HasProperty | understood
Facets:
value: poorly
type: DEGREE
Source sentences:
text: This telltale degeneration can first manifest as tremors, slowness of movement, gait problems and/or rigidity, but the underlying causes of cell death are poorly understood, despite the fact that descriptions of the symptoms date back to Egyptian papyrus, Ayruvedic medical treatises and the writings of Galen.