A pilot study: Auditory steady-state responses (ASSR) can be measured in human fetuses using fetal magnetoencephalography (fMEG).

BACKGROUND: Auditory steady-state responses (ASSRs) are ongoing evoked brain responses to continuous auditory stimuli that play a role for auditory processing of complex sounds and speech perception. Transient auditory event-related responses (AERRs) have previously been recorded using fetal magnetoencephalography (fMEG) but involve different neurological pathways. Previous studies in children and adults demonstrated that the cortical components of the ASSR are significantly affected by state of consciousness and by maturational changes in neonates and young infants. To our knowledge, this is the first study to investigate ASSRs in human fetuses. METHODS: 47 fMEG sessions were conducted with 24 healthy pregnant women in three gestational age groups (30-32 weeks, 33-35 weeks and 36-39 weeks). The stimulation consisted of amplitude-modulated (AM) tones with a duration of one second, a carrier frequency (CF) of 500 Hz and a modulation frequency (MF) of 27 Hz or 42 Hz. Both tones were presented in a random order with equal probability adding up to 80-100 repetitions per tone. The ASSR across trials was quantified by assessing phase synchrony in the cortical signals at the stimulation frequency. RESULTS AND CONCLUSION: Ten out of 47 recordings were excluded due to technical problems or maternal movements. Analysis of the included 37 fetal recordings revealed a statistically significant response for the phase coherence between trials for the MF of 27 Hz but not for 42 Hz. An exploratory subgroup analysis moreover suggested an advantage in detectability for fetal behavioral state 2F (active asleep) compared to 1F (quiet asleep) detected using fetal heart rate. In conclusion, this pilot study is the first description of a method to detect human ASSRs in fetuses. The findings warrant further investigations of the developing fetal brain.

Ultrastructural Changes of Collagen in Different Histopathological Grades of Oral Submucous Fibrosis.

BACKGROUND AND OBJECTIVES: Oral submucous fibrosis (OSMF) is a potentially malignant disorder and a crippling condition of oral mucosa. It is usually seen in adults with areca nut chewing habit, which is characterized by changes in the connective tissue fibers leading to stiffness of the mucosa and restricted mouth opening. Patients with severe cases have distinct difficulties in chewing, swallowing, and speaking. It predominantly occurs in Indians and other population of the Indian subcontinent with a prevalence of 0.2%-0.5%. The potentiality of malignant transformation associated with OSMF is much higher with a range of 4.5%-7.6%. This article is about the ultrastructural changes pertaining to collagen and with respect to the histopathological grades of OSMF. MATERIALS AND METHODS: A total of 20 biopsy samples from clinically diagnosed OSMF subjects and 5 healthy controls were collected. After obtaining the biopsy, the specimens were divided into two halves, of which one was studied under light microscope and the other half was observed under transmission electron microscope. RESULTS: Of the 20 subjects in the study group, most of the subjects were in the 20-29 years age group with an overall male predilection (19 subjects). Four subjects were in grade 1, nine were in grade 2, and seven were in grade 3. Collagen showed sparse to dense fibrosis and normal to thick collagen bundles, and some subjects showed encroachment of collagen into the blood vessels. CONCLUSION: This study showed definitive changes with respect to collagen in the OSMF samples compared to the controls. The changes were found to be increasing with the progression of the disease to the higher grades. The changes were pertaining to the collagen and were drawing toward an increased fibrosis of the connective tissue, which compresses the blood vessels. Hence, the state of hypoperfusion and subsequent epithelial atrophy can be considered in the progression of disease to the higher grades.

Ameloblastic fibrodentinoma involving anterior maxilla: a rare case report.

Ameloblastic fibroma (AF) and related lesions comprise a complex group of mixed odontogenic tumors. Ameloblastic fibrodentinoma (AFD) is a rare tumor and is considered as a histological variant of AF showing inductive changes that lead to the formation of dentin. Although the most common site for this tumor is the posterior mandible, hereby we are reporting a case of AFD in the anterior maxillary region which is a very rare site for this group of tumors. The present case report highlights the clinical, radiological and histological presentation of AFD in order to raise awareness for the earlier diagnosis and precise management of this rare pathological entity.