What are some common causes of microhaemorrhages?
Chronic hypertension and amyloid angiopathy are the most common. Multiple cavernoma syndromes can also cause multiple microhaemorrhages but this is much rarer (and will have other imaging features).
What cause do you favour in this case?
Given the predominant involvement of the basal ganglia and brainstem chronic hypertension is the most likely cause. Amyloid angiopathy microhaemorrhages occur in the periphery of the lobes.
Heterogeneous T1 and T2 signal in the left internal capsule is in keeping with the previously demonstrated haematoma, which is resolving. Confluent periventricular and deep white matter high T2/FLAIR signal. Generalised cerebral atrophy with mild ventriculomegaly. Foci of susceptibility artefact predominantly centred on the basal ganglia with a few in the pons/cerebellum. There are a few supratentorial subcortical foci of susceptibility artefact but these are less prominent.