Klinische Neurophysiologie 2014; 45 - P5
DOI: 10.1055/s-0034-1371218

Mesencephalic raphe alterations depicted by transcranial sonography do not result in serotonergic functional impairment assessed by loudness dependence of auditory evoked potentials in healthy persons

C Krogias 1, G Fischer 2, S Meves 1, R Gold 1, G Juckel 2, C Norra 2
  • 1Ruhr Universität Bochum – St. Josef-Hospital, Neurologie, Bochum, Deutschland
  • 2Ruhr-Universität Bochum – LWL-Universitätsklinik, Psychiatrie, Bochum, Deutschland

Background:

Transcranial sonography (TCS) has become a new diagnostic tool in the evaluation of neuropsychiatric disorders. Hypoechogenic signal of mesencephalic raphe structures has been described as a frequent finding in unipolar depression. It remains unclear, if raphe hypoechogenicity represents a correlate for an altered serotonergic system. The loudness dependence of auditory evoked potentials (LDAEP) has been proposed as an indirect indicator of central serotonergic activity. Aim of this study was to evaluate TCS and LDAEP as independent variables of the human cerebral serotonergic system.

Methods:

Sonographic and electrophysiological investigations of TCS and LDAEP were performed in 44 healthy subjects (28.7+/-7.0 years; 24 females). Echogenicity of basal ganglia and of brainstem raphe (BR) were assessed blindly according to examination protocol for neurodegenerative disorders using a Siemens Sonoline® Elegra system. Psychometric assessment of depressive symptoms and psychological distress was also performed.

Results:

A hypoechogenic signal of brainstem raphe was detected in six subjects (13.6%). Three probands (6.8%) exhibit hyperechogenicity of Substantia nigra. LDAEP values ranged between -2.80 and 8.40mVeff/10dB (mean = 2.31 +/- 2.44 mVeff/10dB). No correlations between LDAEP and sonographic findings were found. There were no significant correlations with the psychometric assessments.

Conclusions:

At least in healthy subjects, our findings do not support the hypothesis, that abnormal structural finding of hypoechogenic BR in TCS is accompanied by a functional impairment of serotonergic system as assessed by LDAEP. Further functional and multimodal imaging studies on patients with depressive disorders are needed to elucidate the impact of the hypoechogenic raphe signal in the pathophysiology of depression.