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fahr 's disease is a rare disorder that was first described by karl theodor fahr in 1930 .
it usually presents with either slow progressive cognitive decline , psychiatric disturbance , or movement disorders .
we describe a patient with an acute deterioration in the level of consciousness and a ct scan demonstrating both subarachnoid blood and idiopathic basal ganglia calcification ( ibgc ) .
further investigations showed a right posterior communicating artery aneurysm to be the source of the hemorrhage .
we postulate that the extensive calcification in fahr 's disease negatively affects both brain parenchyma and intracranial vessels predisposing these individuals to such an acute presentation .
a 54-year - old housewife without any significant previous medical history , or any neurological problem presented with a transient loss of consciousness followed by headache and confusion .
her blood investigation , which included coagulation profile , blood cell count and serum electrolytes , was normal .
brain computerized tomography ( ct ) showed two major findings : first , diffuse bilateral subarachnoid hemorrhage involving the basal cisterns and both sylvian fissures ; and second , extensive calcification involving the basal ganglia , thalamus , corona radiata , and deep cerebellar nuclei [ figure 1 ] .
axial noncontrast ct scan of the brain shows extensive symmetrical calcification at the level of the ( a ) cerebellum , ( b ) basal ganglia , ( yellow arrow ) ( c ) thalamus and ( d ) white matter .
formal cerebral angiography revealed a right posterior communicating artery aneurysm as the probable source of the sah .
an attempt at coiling this aneurysm failed because of a tortuous internal carotid artery precluding safe access to the aneurysm [ figure 2 ] .
right internal carotid angiogram showing a multilobulated right posterior communicating artery aneurysm measuring 7.8  5.7  4.2 mm with the neck of the aneurysm measuring 3.3 mm ( white arrow ) .
the patient was thereafter taken to the operating room where she underwent a right pterional craniotomy and clipping of the posterior communicating artery aneurysm .
her postoperative course was complicated by a right - sided upper extremity monoparesis due to a small middle cerebral artery territory ischemic infarct . however , over the following days she improved but experienced mild vasospasm that was treated medically with euvolemia and milrinone .
she was also investigated for disorders that may cause abnormal calcium deposition which proved negative .
the patient was eventually discharged from the hospital to a rehabilitation program where she showed significant improvement .
the 6-month follow - up angiogram revealed no new aneurysms and no recanalization of the clipped aneurysm .
fahr 's disease , or idiopathic basal ganglia calcification is a rare syndrome that is characterized by abnormal intracranial calcification in the absence of any systemic calcium disorder .
different names have been given to abnormally excessive calcification within the brain parenchyma and cerebral vessels , reflecting the confusion regarding what causes this disorder [ table 1 ] .
names of ibcg with vascular predilections calcification has been described in the globus pallidus , caudate nucleus , putamen , thalamus , dentate nuclei , cerebellar lenticular nucleus , thalamus , the white matter of the cerebral cortex , as well as major intracranial vessels and those supplying the basal ganglia and the cerebellum .
typical presentation starts in the 4th to 5th decade of life with a slow cognitive decline , psychiatric abnormalities or movement disorders such as parkinson 's tremor , dystonia or cerebellar ataxia .
microscopic and biochemical analysis of brain deposits in fahr 's disease reveals that the stroma contains mainly calcium and protein without collagen or mucopolysaccharides .
these deposits occur in vessel walls of arterioles , capillaries , veins , and in the perivascular spaces .
the calcium deposits are generally symmetrical and may be seen in the walls of small and medium sized vessels that could have resulted from inflammatory processes in the vessels . an acute deterioration in the level of consciousness
a potential cause may be a complex - partial seizure as reported in a patient who had had a mild psychiatric disturbanceprior to a seizure episode . in another case , simone et al .
, described a 69- year - old patient who presented with recurrent episodes of deterioration in the level of consciousness and who was found to have classical radiological findings of fahr 's disease , in addition to pseudo - hypoparathyroidism , the correction of which improved his clinical status .
subarachnoid hemorrhage from a ruptured intracranial aneurysm has a poor prognosis with mortality rate of 50% , with 20% of survivors remaining severely disabled .
histopathologically , aneurysms are associated with a loss of the media interna along with the elastic lamina as well as a thinning of the wall .
there is also an associated intimal thickening in the parent artery . in larger aneurysms calcification
may be seen either in the wall of the vessels or at the neck of the aneurysm .
earlier descriptions of fahr 's disease postulate a vascular pathophysiological process with calcification in both small and large vessels .
our case represents ibgc presenting with an sah as a first presentation . despite the heavy calcification seen on imaging she was asymptomatic before the event .
we suggest that this could represent a subset of patients in whom there may be a predilection for intracerebral vessel symptomatology prior to the eventual onset of cognitive and psychiatric disturbances .
the association of ibgc and an intracranial aneurysm has to date remained unreported in the literature .
this case represents a first for fahr 's disease presenting with an aneurysmal subarachnoid bleeding .
fahr 's disease is a chronic slowly progressive neurodegenerative disorder that most commonly will present with acute deterioration in the level of consciousness , secondary to seizures .
we report a case of fahr 's disease in which this acute deterioration was secondary to an aneurysmal subarachnoid hemorrhage .
this observation suggests that a brain cta should be performed in patients with unexplained recurrent episodes of loss of consciousness , to rule out an aneurysm , even if they are known to have ibgc , so as to not attribute it to an epilepsy disorder .
fahr 's disease is a rare disorder of slowly progressive cognitive , psychiatric , and motor decline associated with idiopathic basal ganglia calcification ( ibgc ) and widespread calcification in the brain and cerebellum . 
 acute presentation of ibgc is most often as a seizure disorder ; however , we present a case of an acute ibcg presentation in which the cause of the deterioration was an aneurysmal subarachnoid hemorrhage .