Transthyretin-derived amyloidosis: Probably a common cause of lumbar spinal stenosis

Abstract

Background. Senile systemic amyloidosis (SSA) derived from wild-type transthyretin is a fairly common condition of old individuals, particularly men. The main presentation is by cardiac involvement, which can lead to severe restrictive cardiomyopathy. SSA is, however, a systemic disease, and amyloid deposits may appear in many other tissues but are thought to be without clinical symptoms outside the heart. Amyloid is a very common finding in cartilage and ligaments of elderly subjects, and transthyretin has been demonstrated in some deposits. Lumbar spinal stenosis is also a condition of usually elderly individuals in whom narrowing of the lumbar spinal canal leads to compression of nerves to the lower limbs.

Results. We questioned whether lumbar spinal stenosis sometimes could be a manifestation of undiagnosed SSA. In this first report we have studied the presence of amyloid in material obtained at surgery for spinal stenosis in 26 patients. Amyloid was found in 25 subjects. Transthyretin was demonstrated immunohistochemically in 5 out of 15 studied resected tissues. Four of the positive materials were analyzed with Western blot revealing both full-length transthyretin (TTR) and C-terminal TTR fragments, typically seen in SSA.

Conclusion. We conclude that lumbar spinal stenosis quite frequently may be a consequence of SSA and that further studies are warranted.

Key words::

• apolipoprotein A-I
• lumbar spinal stenosis
• senile systemic amyloidosis
• transthyretin

Acknowledgements

Thanks are due to Ellahe Charkhar and Marianne Ljungquist for skilled assistance.

Declaration of interest: Supported by the Swedish Research Council and the FAMY, FAMY Norrbotten, and Amyl foundation. The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.