there can be a variety of underlying causes such as a head injury, that can occur at any age; a birth injury, such as a lack of oxygen during birth; fever convulsions, encephalitis, meningitis or childhood measles; and metabolic or biochemical disturbances or imbalances.

ku nga va na muxaka wa swivangelo leswi tumbeleke swo tanihi ku vaviseka ka le nhlokweni, loku ku nga humelelaka eka malembe hi vukhale wahi kumbe wahi; ku vaviseka eku velekiweni, ko tanihi ku pfumaleka ka moyatenga hi nkarhi wa ku velekiwa, milombyana ya ku hisa miri, mpfimbabyongo, mpfimbo wa nkuva wa byongo kumbe ximungwamungwana xa vutsongwana; mikavanyeto kumbe mikandzingano ya mpfuvelaseleni kumbe bayokhemikali.
