A Diagnosis of Idiopathic Basal Ganglia Calcification in an 82‐Year‐Old Man (2013)

To the Editor: Idiopathic basal ganglia calcification (IBGC, also known as Fahr's disease) is defined by the presence of brain calcification affecting at least the basal ganglia, with no cause found after extensive etiological assessment.1 The age of clinical onset is classically in the fifth or sixth decade. We report a case with an unusually late onset. An 82-year-old man was seen for a memory trouble that had begun within the 2 years preceding the consultation. His medical history included a cardiac conduction disorder requiring pacemaker implantation. He had no personal or familial history of neuropsychiatric disorders. The presence of a subtle asymmetric akinetic-hypertonic syndrome without tremor was noted upon examination. The rest of the neurological and general examination was unremarkable. Neuropsychological assessment revealed impaired verbal episodic memory characterized by impaired encoding (free recall, 16/48; threshold, 17), with efficient cueing (total recall, 39/48; threshold, 39) on the Free and Cued Selective Recall Reminding Test (FCSRT). This pattern is consistent with frontal subcortical dysfunction.2 Executive function assessment was normal, as was evaluation of other cognitive functions (oral naming, gestural praxis, Rey figure copy), with normal global scores (Mattis dementia rating scale score 132/144, Mini-Mental State Examination score 28/30). Neither he nor his wife or children reported deterioration in daily living skills (Functional Activities Questionnaire score 0). It was therefore concluded that the patient had amnestic mild cognitive impairment (MCI).3 Computed tomography (CT) revealed the presence of striopallidodentate and supratentorial white matter calcification (Figure 1) together with diffuse mild cortical and subcortical atrophy. An extensive etiological assessment (as described elsewhere1) found no significant abnormalities, leading to the diagnosis of IBGC. No mutation was found in the SLC20A2 or PDGFRB genes. Heterozygous mutations in these genes are causes of dominantly inherited IBGC in some families, but other genes remain to be determined.1 The symptoms associated with IBGC are diverse, the most common including movement disorders, psychiatric signs, cognitive impairment, dysarthria, gait disorder, cerebellar syndrome, pyramidal signs, and seizures.4 The association between cognitive impairment and movement disorders such as akinetic-hypertonic syndrome and hyperkinetic movements is suggestive of basal ganglia involvement, especially when the pattern of the memory impairment on FCSRT is consistent with subcortical dysfunction. Here, CT led to immediate consideration of the diagnosis of IBGC, which was confirmed after excluding known causes of basal ganglia calcification. In addition, the other common causes of amnestic MCI in older adults seemed unlikely: the patient had neither history of stroke nor vascular lesions on CT scan;5 the memory impairment was characterized by efficient cueing, which does not suggest the cortical memory impairment seen in Alzheimer's disease;6 and he did not fulfill the criteria for dementia with Lewy bodies.7 The age of clinical onset of IBGC is typically in the fifth or sixth decade, but symptoms can begin at any age, ranging from early childhood to late adulthood. Nevertheless, such a late presentation has very rarely been reported.8 The clinical penetrance of IBGC is incomplete, which is consistent with such late clinical presentation. Because intrafamilial diversity is classic in IBGC, it is possible that some of his relatives may have asymptomatic IBGC and may develop clinical signs later, possibly before their 80s. Moreover, it is not possible to date the beginning of calcification. Neurologically uncomplicated aging can be associated with basal ganglia calcification, typically restricted to the lenticular nuclei.9 Normative data would be useful to help diagnose cases with calcification of borderline severity.10 Nevertheless, in this case, lenticular calcification was associated with caudate, dentate, and white matter calcification (Figure 1), which is not consistent with normal aging. In conclusion, this clinical report illustrates that the range of age and clinical severity in IBGC is broad. In addition to the individual presenting with the first signs of the disease at an unusually advanced age, he presented with a rather mild form of the disease (MCI with faint extrapyramidal signs). Diagnosing pathological basal ganglia calcification is important even in old age, for at least three reasons: etiological assessment can allow a cause to be identified and then influence the clinical outcome and treatment, diagnosing IBGC permits the large spectrum of clinical expression of IBGC to be considered, and younger relatives can be informed about IBGC because there is greater intrafamilial diversity in terms of age of clinical expression. Conflict of Interest: The editor in chief has reviewed the conflict of interest checklist provided by the authors and has determined that the authors have no financial or any other kind of personal conflicts with this paper. Author Contributions: Study concept and design: Nicolas. Acquisition of subjects and data: Nicolas, Wallon, Salle, Dreano, Martinaud, Borden, Campion, Hannequin. Analysis and interpretation of data: Nicolas, Wallon, Salle, Dreano, Martinaud, Borden, Campion, Hannequin. Preparation of manuscript: Nicolas, Wallon, Borden, Hannequin. Sponsor's Role: No specific role of the funding source.