Correlation Between Orofacial Pain and Sensory and Autonomic Neuropathies

Shruti Handa,1 Megan R Heffernan,2 Summer Tan,3 David A Keith,1 Annika Rosén,4– 6 Hsinlin Thomas Cheng7 1Division of Oral and Maxillofacial Surgery, Department of Surgery, Massachusetts General Hospital and Harvard School of Dental Medicine, Boston, MA, USA; 2Department of Neurology, Massachusetts General Hospital, Boston, MA, USA; 3Department of Dentistry, Harvard School of Dental Medicine, Boston, MA, USA; 4Department of Oral and Maxillofacial Surgery, Eastman Institute, Stockholm, Sweden; 5Department of Clinical Dentistry, University of Bergen, Bergen, Norway; 6Department of Oral and Maxillofacial Surgery, Haukeland University Hospital, Bergen, Norway; 7Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USACorrespondence: Shruti Handa, Department of Surgery, Massachusetts General Hospital, 165 Cambridge Street, Suite &num;401, Boston, Massachusetts, 02114, USA, Email shanda1@mgh.harvard.eduPurpose: Orofacial Pain (OFP) affects 15% of the general population. OFP conditions can be myofascial, also known as temporomandibular disorders (TMDs) or neuropathic. The underlying pathophysiology in several chronic OFP conditions, is unknown. Small fiber neuropathy (SFN) is a disorder of thinly myelinated A-delta and non-myelinated C-fibers and can manifest as sensory and autonomic neuropathies. SFN has been demonstrated in some OFP conditions. Our study aims to assess the presence of OFP in patients with sensory and autonomic neuropathies and assess the correlation between OFP, skin biopsy and autonomic dysfunction.Patients and Methods: This is a retrospective study (2018– 2020) of patients from the SFN registry, Massachusetts General Hospital, Boston, USA, for the presence of OFP. All patients were included. Primary outcome: Prevalence of OFP in patients with chronic neuropathies. Secondary outcomes: Correlation between OFP and skin biopsy, dysautonomia, headaches, chronic nociceptive pain, psychological conditions, and patient factors, such as mean age and BMI.Results: Charts of 450 patients with sensory and autonomic neuropathies were reviewed. 22.67% (n=102) had OFP. The mean (range) age at biopsy in patients with OFP was 48.36 (20– 81) years, female: male ratio 3.25:1. More OFP patients had negative skin biopsy results (p value< 0.05) than those with sensory neuropathies. Patients with OFP had significantly higher prevalence of psychological conditions (p value 0.000), and higher BMI > 30 (p value 0.025). Dysautonomia was significantly higher in patients with TMDs when compared to the ones without TMDs (p value 0.030). There was no significant difference in mean age, gender predilection, presence of headaches, peripheral neuropathies, and nociceptive pain between patients with and without OFP.Conclusion: OFP and sensory neuropathies can be overlapping conditions. Patients presenting with concomitant TMD and dysautonomia can be further tested for SFN. This can further help us understand a correlation if any, between idiopathic TMD/OFP conditions and SFN and further our understanding of the pathophysiology of these conditions.Keywords: idiopathic facial pain, orofacial pain, temporomandibular disorders, skin biopsy, autonomic dysfunction, sensory neuropathic pain, dysautonomia, small fiber neuropathy