Lumbar spinal canal stenosis: An early sign of amyloid transthyretin related amyloidosis

Amyloid transthyretin-related amyloidosis (ATTR) onsets due to the extracellular multiorgan deposition of misfolded transthyretin, a serum protein that synthesizes mainly in the liver. Two different forms of the disorder have been identified to date, namely wild-type ATTR (wtATTR), previously referred to as “senile” since it was mainly diagnosed in the elderly; and an inherited ATTR (hAATR), caused by mutant transthyretin. ATTR amyloidosis is often overlooked or misdiagnosed owing to its non-specific presentation. Amyloid deposits can determine musculoskeletal manifestations, such as carpal tunnel syndrome (CTS), lumbar spinal canal stenosis (LSCS), or distal biceps tendon rupture (DBTR) several years before any cardiac manifestations, particularly in patients with wtATTR. Cardiac manifestations of wtATTR (wtATTR-CA) include aortic stenosis, hypertrophic cardiomyopathy, heart failure with preserved ejection fraction, and hypertensive cardiomyopathy, although the cardiac signs and symptoms resemble those of other cardiovascular conditions of different etiology during the course of the disease [1]. We present radiological images of an 80-year-old man who had wtATTR-CA and LSCS. At the age of 65, he had had bilateral CTS. Ten years later, he began to report pain and loss of strength in the lower limbs mainly localized in the buttocks and quadriceps. Computed tomography (CT) of the spine showed a LSCS due to ligamentum flavum hypertrophy (LFH) considered to result from fibrous degeneration (Figure 1A). ATTR-CA was diagnosed (Figure 1C) four years later. Genetic investigations yielded a negative result for hATTR. Upon further investigation, spinal magnetic resonance imaging (Figures 1D, E) and a second CT scan of the spine (Figure 1B) showed significant LFH with narrowing of the spinal canal.