The condition, named after German neurologist Karl Theodor Fahr, was first documented in 1930. This is a rare neurological condition characterized by abnormal idiopathic calcification of the basal ganglia and is usually inherited in an autosomal dominant manner. Etiology remains to be elucidated.

The association between Fahr’s disease and intracranial aneurysms is exceedingly rare, with only five cases documented in the literature to date (Table 1). This report represents the sixth such case. Furthermore, all previously reported aneurysms were confined to the anterior circulation; thus, this is the first documented instance of Fahr’s disease presenting with an aneurysm in the posterior circulation.

We present a case of Fahr’s disease complicated by a ruptured basilar tip aneurysm, detailing its management and the associated challenges encountered during treatment.

A 40-year-old gentleman arrived at the emergency department with a sudden, intense headache and vomiting that had persisted for one day. On Clinical Examination, he was conscious, disorientated, and cooperative. Pupils were isochoric, bilateral light reflex was positive, and there was no motor deficit. Glasgow’s Coma Score was E4V4M6 and the pain score was 10/10. An urgent computed tomography (CT) Head was done which showed Extensive subarachnoid hemorrhage (SAH) on a background of Fahr’s disease (Fig. 1). A corroborative CT Angio showed a wide-necked tubular aneurysm arising from the tip of the Basilar artery directed superiorly. It measured 15×8.9×6 mm with a neck of 4.5 mm.

Since the patient had presented with acute bleed, a plan was made to deploy a neck bridging device along with coiling to facilitate occlusion of the aneurysm. The decision was based on the surgeon’s expertise, aneurysm morphology, and patient’s preference. During the procedure, the angiography showed a single tubular aneurysm with irregular wall arising from the basilar tip (Fig. 2). The posterior cerebral and superior cerebellar arteries were arising below the neck of the aneurysm. A Neqstent endosaccular device 11 mm (Stryker-NQS21411-17, Portage, MI, USA) was selected according to the size chart provided. It was advanced through the microcatheter (Headway 0.021, Terumo Neuro, Aliso Viejo, CA, USA) and deployed just above the aneurysm neck while another microcatheter (Select LP- 0.0165, Cerenovus, Irvine, CA, USA) was jailed within the aneurysm sac. During placement of the first framing coil, contrast extravasation was noted most likely associated with Intraprocedural aneurysm rupture. There was a sudden increase in the BP of the patient. Additional coils were placed to completely occlude the aneurysm sac. Immediate reversal of Heparin was done and prophylactic external ventricular drain (EVD) was placed. Once coiling was completed, the microcatheter was withdrawn from the aneurysmal sac. The Neqstent was detached using its detachment system, after confirming its proper position.

Post-coiling cerebral angiogram showed complete occlusion of the basilar tip aneurysm with good flow across the bilateral posterior cerebral arteries, and the superior cerebellar arteries (Figs. 3, 4).

Since the patient presented to us for the first time in emergency department, initial management was done to treat the SAH as she had a poor grade SAH. Post aneurysmal treatment, the patient was worked up for Fahr’s disease and the family was also screened for the same.

Routine blood investigations and complete metabolic panel were normal, including the absence of any biochemical abnormalities suggestive of disorders of calcium metabolism, endocrinopathies, mitochondrial or systemic disorder, and heavy metal poisoning.

A cerebrospinal fluid (CSF) analysis was done which was negative for any infective etiology and autoimmune markers. On detailed family history evaluation, the patient’s father was found to have features of Parkinsonism and bilateral basal ganglia calcification on non-contrast head CT (NCCT) head. Since the patient had a poor grade SAH, and due to cost and infrastructure constraints a detailed genetic evaluation could not be carried out.

But due to the absence of any metabolic and somatic features suggestive of mitochondrial or metabolic disease, absence of any infectious, toxic, or traumatic cause, and presence of Parkinsonism symptoms and bilateral basal ganglia calcification in family members, a diagnosis of Fahr’s disease was most strongly considered.

Fahr’s disease, known as familial idiopathic calcification of the basal ganglia, is a rare condition that can be inherited in an autosomal dominant manner, transmitted through families, or appear sporadically. In addition to genetic influences, this disease may arise from anoxia or issues related to calcium metabolism during development [2]. Fahr’s disease is extremely rare with a prevalence of less than 1/1000,000 [7]. In adults without specific risk factors, the prevalence of aneurysms is about 2%. The majority of these aneurysms are small and have a yearly risk of rupture of about 0.7% [12]. However, the incidence of intracranial aneurysms in patients with Fahr’s disease is still unreported.

Idiopathic Fahr’s disease, characterized by basal ganglia calcifications, can be linked to various neurological and metabolic conditions. A genetic defect that occurred in the short arm of chromosome 14 is thought to be responsible [11]. Calcifications frequently appear in radiological images of asymptomatic individuals. Some level of basal ganglia calcification is regarded as a normal aspect of aging after the age of 50 and may be incidentally detected in 15-20% of asymptomatic patients undergoing CT scans [4].

The unusual calcium deposition observed in Fahr’s disease is believed to arise from disruptions in brain calcium metabolism or metastatic deposits due to localized changes in the blood-brain barrier. Deficiencies in iron transport mechanisms may lead to tissue damage, initiating calcification around a central core. Microscopic and biochemical studies of brain deposits in Fahr’s disease indicate that the stroma primarily consists of calcium and protein, lacking the collagen or mucopolysaccharides typically found in the walls of arterioles, veins, capillaries, and perivascular spaces [3]. These deposits are usually symmetrical and may be associated with inflammatory processes in the vessels [5]. There is loss of the media interna and elastic lamina, thinning of the vessel wall, and intimal thickening in the parent artery. In larger aneurysms, calcification can occur either in the vessel wall or at the neck of the aneurysm [16]. As calcification advances, it can compress adjacent vessels, leading to reduced blood flow and establishing a cycle of diminished perfusion, tissue damage, and further mineral deposition.

Patients with Fahr’s disease may be asymptomatic, but symptoms typically begin in the fourth or fifth decade of life. Calcifications predominantly occur in the Globus Pallidus, potentially resulting in gradual cognitive decline, psychiatric problems, or movement disorders such as Parkinson’s tremor, dystonia, cerebellar ataxia, or seizures. In the case mentioned, the patient presented only with headaches. CT imaging is the preferred diagnostic tool for Fahr’s disease because of its effectiveness in detecting calcifications.

Acute presentations of Fahr’s disease are most often characterized by seizures, and some patients may experience recurrent episodes of impaired consciousness alongside pseudo-hypoparathyroidism, with correction improving their clinical condition [15]. Subarachnoid haemorrhage due to a ruptured intracranial aneurysm generally carries a poor prognosis, featuring a 50% mortality rate, with 20% of survivors facing severe disabilities [9]. In such cases, vessel wall MRI is valuable for assessing calcification and inflammation in the aneurysm wall and its neck, helping to predict the risk of rupture during surgical intervention.

Despite the significant calcification visible on imaging, our patient remained asymptomatic prior to the event. This may suggest a subset of individuals who develop intracerebral vessel issues before manifesting cognitive or psychiatric symptoms. At presentation, the patient experienced severe headache and vomiting, with imaging revealing a subarachnoid hemorrhage and a basilar tip aneurysm. Posterior circulation aneurysms are challenging to access transcranially. The decision for endovascular intervention was guided by the surgeon’s expertise and the patient’s preferences. Coiling is associated with a shorter recovery time and early discharge than clipping, and it may be safer for high-risk patients. However, coiling can have complications, as seen in our case. Intraoperative rupture may have been exacerbated by vessel pathology associated with Fahr’s disease. The likely cause of rupture could be

1. Sudden change in intra-aneurysmal hemodynamics after placement of Neqstent which changed the shear stress on the aneurysmal wall.

2. Microcatheter displacement during coiling. The jailed microcatheter may have pushed across the aneurysmal wall as the rupture happened during the first coil placement.

3. Underlying Fahr’s disease causes weakening of the vessel wall which predisposes to rupture.

Managing a rupture during coiling is challenging. Aneurysmal rupture is indicated by clinical signs, such as the Cushing reflex, or by fluoroscopic evidence showing that a device (coil, guidewire, or microcatheter) is located outside the aneurysm. Confirmation of the rupture is done through contrast injection, which reveals extravasation. If a balloon-assisted technique is employed, the balloon is promptly inflated across the neck of the aneurysm to temporarily control bleeding, allowing time to securely close the breach. If a balloon is not used, the protocol includes reversing heparin with intravenous protamine sulphate, lowering blood pressure, placing a ventricular drain if necessary, and sealing the breach endovascularly with additional coil placement. A ventricular drain is also indicated if there are signs of increased intracranial pressure or hydrocephalus.

Although intraventricular haemorrhage was addressed with EVD insertion, it has a poor prognosis with a mortality rate of 50-80% [8]. Fahr’s disease vasculitis causes reduced blood flow and establishes a cycle of diminished perfusion, tissue damage, and further mineral deposition. This further worsens the patient’s prognosis. Our patient, although recovered postoperatively, expired after a few days.

The exact mechanisms underlying Fahr’s disease are not fully understood, but it is believed to play a role in the development of aneurysms due to mineral deposits in blood vessels. This condition is chronic and progresses slowly over time. While there are some rare case reports, a clear connection between Fahr’s disease and aneurysms has not yet been definitively established. For patients experiencing unexplained recurrent episodes of loss of consciousness, brain CTA should be performed to rule out an aneurysm, even if they have a known diagnosis of Fahr’s disease, to prevent misattributing these episodes to epilepsy. Family of the patient should also be screened since it is inherited in an autosomal dominant manner. Additionally, vessel wall MRI should be conducted preoperatively in cases of aneurysms linked to Fahr’s disease or vasculitis to improve management planning.