Effect of Retinohypothalamic Tract Dysfunction on Melatonin Level in Patients with Chronic Disorders of Consciousness.

Mikhail Kanarskii,Elena Borisova,Marina V Petrova,Sergey Peshkov,Ilya Borisov,Igor Pryanikov,Pranil Pradhan,Julia Nekrasova,Olga Panasenkova,Svetlana Vitkovskaya

doi:10.3390/brainsci11050559

Abstract

Objective: The aim of this study is to compare the secretion level of nocturnal melatonin and the characteristics of the peripheral part of the visual analyzer in patients with chronic disorders of consciousness (DOC). Materials and Methods: We studied the level of melatonin in 22 patients with chronic DOC and in 11 healthy volunteers. The fundus condition was assessed using the ophthalmoscopic method. Results: The average level of nocturnal melatonin in patients with DOC differed by 80% from the level of indole in healthy volunteers. This reveals a direct relationship between etiology, the level of consciousness, gaze fixation, coma recovery scale-revised score and the level of melatonin secretion. Examination by an ophthalmologist revealed a decrease in the macular reflex in a significant number of DOC patients, which in turn correlates negatively with the time from brain injury and positively with low values of nocturnal melatonin.

Highlights

Severe traumatic brain injuries (TBIs), cerebral vascular lesions (VLs), respiratory and cardiac arrest, and gross metabolic disorders often lead to a coma—a condition characterized by the absence of a qualitative and quantitative component of consciousness, structurally or functionally caused by damage to the ascending reticular formation or rostral midbrain or extensive lesions of the cerebral hemispheres
We made equal samples of participants according to the etiology of the disorders of consciousness (DOC), with 11 patients each, reflecting anoxic and traumatic brain injury
The aim of this work was to assess the effect of dysfunction of the retinohypothalamic tract on the level of melatonin in patients with chronic DOC

Summary

Introduction

Severe traumatic brain injuries (TBIs), cerebral vascular lesions (VLs), respiratory and cardiac arrest, and gross metabolic disorders often lead to a coma—a condition characterized by the absence of a qualitative and quantitative component of consciousness, structurally or functionally caused by damage to the ascending reticular formation or rostral midbrain or extensive lesions of the cerebral hemispheres. Coma is a transient state, its outcome can be either clear consciousness or, under less favorable circumstances, death or severe disorders of consciousness (DOC), such as vegetative state (VS) or minimally conscious state (MCS) [1,2]. In these conditions, the detection of minimal signs of consciousness or communication is of great importance. A special type of ganglion cell that expresses the light-sensitive pigment melanopsin represents the main peripheral component of this tract These cells provide information on the intensity of light reaching the retina and direct their processes along the retinohypothalamic tract to the SCN of the hypothalamus [8]. The presence of melatonin receptors in almost all tissues explains the properties of melatonin as one of the key clock molecules of the body [10]

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Discussion

Conclusion