Trouble psychotique secondaire à un syndrome de Fahr : à propos d’une observation

Abstract

Fahr's syndrome is a rare disorder characterized by abnormal deposits of calcium in areas of the brain that control movement, including the basal ganglia and the cerebral cortex associated with many neurological and psychiatric abnormalities such as a rigid hypokinetic syndrome, mood disorders and cognitive impairment. Fahr's syndrome is secondary to some disorders, such as hypoparathyroidism. We report the case of a 56 year-old man, with a history of cataract, who was admitted to our psychiatric hospital for the first time in his life because of psychotic symptoms associated with irritability and aggressiveness. Since the age of 38 the patient had become nervous, 10 years later he developed tonic-clonic seizures. Two months ago, he began expressing delusions of persecution against his wife and sons and making fugues. According to his family during this period, he was agitated, aggressive, and suffered from insomnia and anorexia. The general and psychiatric examination showed an upright and bronzed patient with neglected hygiene. He was indifferent to his environment and expressed poor mimics and gestures. He was anxious, suspicious and not very talkative. He was conscious but his attention was slightly decreased. Moreover, he was not aware of his problems. The neurological examination showed extrapyramidal syndrome with postural tremor and cerebellar ataxia. A cranial computed tomography brain scan found bilateral, symmetric basal ganglia calcifications, in favour of Fahr's syndrome. Phosphocalcic investigations revealed low concentration of serum calcium at 1.01mmol/L (normal 2.15 to 2.57mmol/L) and hyperphosphoremia at 2.69mmol/L (normal 0.81 to 1.55mmol/L). He also had low concentrations of 25-OH vitamin as well as decreased urinary levels of phosphate and calcium. The blood level of parathyroid hormone was 0ng/L. The diagnosis of Fahr's syndrome, revealing a hypoparathyroidism was posed. He was supplemented with calcium and alpha cholecalciferol and treated with clozapine (100mg per day). After four weeks, psychotic symptoms responded well to this treatment without expressing any side effects, notably seizures. Psychotic symptoms seen in Fahr's disease include auditory and visual hallucinations, complex perceptual distortions, delusions, and fugue state. Some of them were manifest in this patient. It is likely that the psychosis in both Fahr's disease and schizophrenia share a similar pathology. Positive psychotic symptoms, hallucinations, and paranoia are not necessarily generated by the classical hypothesis of dopamine-mediated attachment of salience to internally generated stimuli. Still, there is some evidence that disruption of the cortex involved in the pathophysiology of schizophrenia is also seen in Fahr's disease, particularly in areas of the limbic system. Psychiatrists should consider Fahr's syndrome as a differential diagnosis in the evaluation of psychosis associated with seizures. This case, along with others in the literature, further emphasizes the importance of the role of neuro-imaging and the search for disrupted phosphocalcic metabolism in patients with atypical psychotic symptoms. Moreover, further research should focus on pharmacologic interventions. The efficacy and risks of neuropharmacologic and psychopharmacologic interventions in Fahr's syndrome, and correlates of good and poor outcome with these interventions remain to be defined.