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. 2023 Jun 5;17(6):e0011383.
doi: 10.1371/journal.pntd.0011383. eCollection 2023 Jun.

Evidencing leprosy neuronal inflammation by 18-Fluoro-deoxy-glucose

Patricia Sola Penna  1 , Sergio Augusto Lopes De Souza  2 , Paulo Gustavo Limeira Nobre De Lacerda  2 , Izabela Jardim Rodrigues Pitta  3 , Clarissa Neves Spitz  1   3   4 , Anna Maria Sales  3 , Flavio Alves Lara  5 , Ana Caroline Siquara De Souza  1   3 , Euzenir Nunes Sarno  3 , Roberta Olmo Pinheiro  3   6   7 , Marcia Rodrigues Jardim  1   3   4   6   7
Affiliations

Evidencing leprosy neuronal inflammation by 18-Fluoro-deoxy-glucose

Patricia Sola Penna et al. PLoS Negl Trop Dis. .

Abstract

Background: Leprosy is caused by multiple interactions between Mycobacterium leprae (M. leprae) and the host's peripheral nerve cells. M. leprae primarily invades Schwann cells, causing nerve damage and consequent development of disabilities. Despite its long history, the pathophysiological mechanisms of nerve damage in the lepromatous pole of leprosy remain poorly understood. This study used the findings of 18F-FDG PET/CT on the peripheral nerves of eight lepromatous patients to evaluate the degree of glucose uptake by peripheral nerves and compared them with clinical, electrophysiological, and histopathological evaluations.

Methods: Eight patients with lepromatous leprosy were included in this study. Six patients were evaluated up to three months after leprosy diagnosis using neurological examination, nerve conduction study, 18F-FDG PET/CT, and nerve biopsy. Two others were evaluated during an episode of acute neuritis, with clinical, neurophysiological, and PET-CT examinations to compare the images with the first six.

Results: Initially, six patients already had signs of peripheral nerve injury, regardless of symptoms; however, they did not present with signs of neuritis, and there was little or no uptake of 18F-FDG in the clinically and electrophysiologically affected nerves. Two patients with signs of acute neuritis had 18F-FDG uptake in the affected nerves.

Conclusions: 18F-FDG uptake correlates with clinical neuritis in lepromatous leprosy patients but not in silent neuritis patients. 18F-FDG PET-CT could be a useful tool to confirm neuritis, especially in cases that are difficult to diagnose, such as for the differential diagnosis between a new episode of neuritis and chronic neuropathy.

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Conflict of interest statement

The authors have declared that no competing interests exist.

Figures

Fig 1
Fig 1. Coronal and axial slices of 18F-FDG PET/CT show no uptake at the peripheral nerves (patients 1 and 3), such as the sural nerve (blue asterisk).
Fig 2
Fig 2. Coronal and axial slices of 18F-FDG PET/CT show different levels of uptake at the peripheral nerves (blue asterisks), such as the sural and tibial nerve (patients 2 and 4), and ulnar and cutaneous nerve (patient 6), as seen at the color scale as orange to white.
Fig 3
Fig 3. Maximum intensity projection (MIP).
18F-FDG PET/CT shows high uptake (patient 8) in bilateral ulnar (blue arrows), sural, and superficial peroneal nerves.
See this image and copyright information in PMC

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