Primary Hypoparathyroidism Mimicking Ankylosing Spondylitis in a Young Man with Fahr's Syndrome: A Case Report

Abstract

Patients with chronic idiopathic hypoparathyroidism may develop neurological complications, including calcification of the basal ganglia and other areas of the brain. In Fahr's syndrome, intracranial calcification is associated with an underlying disorder such as hypo or hyperparathyroidism. We report the case of a 37-year-old gentleman, with a history of bilateral cataract surgery and seizures, who presented with a new episode of seizure and was found to have severe hypocalcemia and bilateral symmetric intracranial calcification due to previously diagnosed primary hypoparathyroidism. He had symptoms and signs mimicking ankylosing spondylitis (AS), but with negative radiological and serological findings, not fitting into the diagnosis of axial spondyloarthropathies (SpA), as per standard criteria. Patients with long-standing idiopathic hypoparathyroidism can have severe calcification of soft tissues and bones, including vertebrae and paravertebral soft tissues, causing inflammatory back pain and stiffness. It is vital to report such cases as their occurrence is rare, and physicians should be aware of the possibility while evaluating patients with inflammatory back pain. Treatment in these cases is directed towards hypocalcemia and underlying primary pathology rather than spondyloarthropathy.

Keywords: fahr’s syndrome; hypocalcemia; hypoparathyroidism; spondyloarthropathies.

Figure 1. Brain imaging shows intracranial calcification

Computed tomography (CT) scan of the brain shows, (A) - bilateral tiny deep white matter calcifications (arrows), (B) - prominent basal ganglia, thalami and posterior juxtacortical calcifications (arrows), and (C) - pontine, and cerebellar folia calcifications (arrows). Brain magnetic resonance imaging (MRI) demonstrates, (D) - expected blooming hypo intensity of the calcifications on susceptibility-weighted imaging (SWI), (E) - hyperintensity on T1 weighted imaging (arrows), and (F) - abnormal hyperintensity in the deep white matter on fluid-attenuated inversion recovery (FLAIR) sequence (arrows) of brain MRI, surrounding the tiny calcifications seen on the CT scan.

Figure 2. (A) Radiograph and (B) coronal T2 weighted fat suppressed inversion recovery MRI shows normal sacroiliac joints bilaterally (arrows)

Figure 3. Lateral radiographs of the (A) cervical, (B) thoracic and (C) lumbar spine show no evidence of syndesmophytes, bamboo spine, or ossification of spinal ligaments, joints, or discs excluding ankylosing spondylitis

Figure 4. Ultrasound images showing no parathyroid lesions and a small nodule in the left lobe of an otherwise unremarkable thyroid gland