Spontaneous upper limb monoplegia secondary to probable cerebral amyloid angiopathy

Cerebral amyloid angiopathy is an important yet often unrecognised cause of primary intracerebral haemorrhage (PICH). Typically amyloid β-protein (Aβ) is deposited within the walls of cortical arteries, veins, capillaries and leptomeningeal vessels [1]. Deposition of Aβ within these structures can lead to infarction and haemorrhage [2,3]. In the absence of definitive histological examination the condition cannot be diagnosed, and cases are termed "probable" or "possible" on the basis of imaging studies. Often the diagnosis is overlooked as a causative agent of PICH despite evidence that suggests up to 40% of elderly brains contain cerebrovascular amyloid [4]. Indeed post-mortem evidence suggests that up to 10% of all PICHs are attributable to cerebral amyloid angiopathy (CAA) [4]. Herein we described, to our knowledge, the unique case of a patient who presented with isolated right upper limb weakness secondary to probable cerebral amyloid angiopathy.A 77-year-old female presented to our emergency department with a history of sudden right upper limb weakness and altered sensation. The patient was previously fit and well with an unremarkable medical history. On examination, she was apyrexial, normotensive and normoglycaemic with a Glasgow Coma Scale of 15/15. Neurological examination revealed right upper limb hypotonia and power of 0/5 in all hand and wrist muscle groups, 2 over 5 power in biceps and triceps, and 3/5 power in the shoulder girdle. Hypoaesthesia was noted throughout the right upper limb. The remainder of the neurological examination did not reveal any other deficits. Baseline blood investigations were normal. An urgent CT brain was performed and demonstrated a peripheral acute haematoma involving the left perirolandic cortices with extension over the left lateral cerebral convexity (Figure 1a,b). Blood was also noted tracking within the left central sulcus on a background of modest cerebral small vessel disease and generalised cerebral volume loss. Brai