Investigating the neuroanatomical substrate of pathological laughing and crying in amyotrophic lateral sclerosis with multimodal neuroimaging techniques

Abstract

Objective: Pathological laughing and crying (PLC) is common in several neurological and psychiatric diseases and is associated with a distributed network involving the frontal cortex, the brainstem and cortico-pontine-cerebellar circuits. By applying multimodal neuroimaging approach, we examined the neuroanatomical substrate of PLC in a sample of patients with amyotrophic lateral sclerosis (ALS). Methods: We studied 56 non-demented ALS patients and 25 healthy controls (HC). PLC was measured in ALS using the Center of Neurologic Study Lability Scale (CNS-LS; cutoff score: 13). All participants underwent 3D-T1-weighted and 30-directional diffusion-weighted imaging at 3T. Voxel-based morphometry and tract-based spatial-statistics analysis was used to examine gray matter (GM) and white matter (WM) differences between ALS patients with and without PLC (ALS-PLC and ALS-nonPLC, respectively). Comparisons were restricted to regions with detected differences between ALS and HC, controlling for age, gender, total intracranial volume and depressive symptoms. Results: In regions with significant differences between ALS and HC, ALS-PLC patients showed decreased GM volume in left orbitofrontal cortex, frontal operculum, and putamen and bilateral frontal poles, compared to ALS-nonPLC. They also had decreased fractional anisotropy in left cingulum bundle and posterior corona radiata. WM abnormalities were additionally detected in WM associative and ponto-cerebellar tracts (using a more liberal threshold). Conclusions: PLC in ALS is driven by both GM and WM abnormalities which highlight the role of circuits rather than isolated centers in the emergence of this condition. ALS is suggested as a useful natural experimental model to study PLC.

Keywords:

• Pathological laughing and crying
• gray matter
• white matter
• neuroimaging

Acknowledgements

F.C. was supported by the IKY FELLOWSHIPS OF EXCELLENCE FOR POSTGRADUATE STUDIES IN GREECE - SIEMENS PROGRAM (SPHA:11118/13a) and IKY SHORT TERMS PROGRAM (2013-ΠΕ2-SHORT TERMS-18671). We acknowledge Odysseas Benekos, Giannis Spandonis and the Philips Medical System for providing all necessary research keys for MRI sequence acquisition. We also acknowledge the radiologists-technologists of Research Radiology & Medical Imaging Department (Ioannis Gkerles, Christos Lioulios, Anestis Passalis, Efstathios Xenos) for conducting and facilitating participants’ MR scanning. Part of this study was presented at the 7^th International Symposium on NeuroImaging in ALS (2016) and the 5^th International Congress on Neurobiology, Psychopharmacology & Treatment Guidance (2017) and we would like to acknowledge all attenders for their constructive comments. Finally, we would like to thank patients with ALS and their families, as well as healthy volunteers for their willingness to participate to the present study.

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this article.

Supplementary material available online.