The Premonitory Phase of Migraine – What Can We Learn From It?

This review aims to understand the prevalence of premonitory symptoms in migraine, postulate their mechanisms, and compare these with functional imaging studies. A thorough literature review was conducted using PubMed for prevalence studies of premonitory symptoms in migraine and functional imaging studies in the premonitory phase. The majority of studies have been retrospective reporting a prevalence of 7‐88% for premonitory symptoms in migraine. Only one study has investigated premonitory symptoms prospectively and used preselected patients with recognized premonitory symptoms. The majority of patients were able to predict correctly the onset of migraine headache. Only one functional imaging study has been conducted in the premonitory phase that showed activation of posterolateral hypothalamus, midbrain tegmental area and substantia nigra, periaqueductal gray, dorsal pons, and various cortical areas including occipital, temporal, and prefrontal cortex. Subgroup analysis of patients with photophobia more than without photophobia in the premonitory phase showed activation of the occipital cortex. Comparison of patients with nausea more than without nausea in the premonitory phase showed activation in upper dorsal medulla and periaqueductal gray. Premonitory symptoms are common in migraine, although the true prevalence cannot be stated with certainty in the absence of prospective studies in unselected patients. Hypothalamic involvement can explain many of the premonitory symptoms. Activation of the the brainstem structures and hypothalamus before pain suggests a pivotal role of these structures in the pathogenesis of migraine. Hypersensitivity to light and occurrence of nausea in migraine is associated with activation of central brain structures involved in these pathways, and this can occur in the absence of pain.     

The origin of nausea in migraine–A PET study

Background

Nausea is a common and disabling symptom of migraine. The origin of nausea is not well understood although functional connections between trigeminal neurons and the nucleus tractus solitarius may explain occurrence of nausea with pain. However, nausea occurs as a premonitory symptom in about a quarter of patients, suggesting that a primary brain alteration unrelated to the experience of pain may be the reason for nausea.

Methods

We performed positron emission tomography scans with H₂¹⁵O PET in premonitory phase of nitroglycerin-induced migraine and compared patients with and without nausea.

Results

The results showed activation in rostral dorsal medulla and periaqueductal grey (PAG) in the nausea group, which was absent in the no nausea group. The rostral dorsal medullary area included the nucleus tractus solitarius, dorsal motor nucleus of the vagus nerve and the nucleus ambiguus, all of which are thought to be involved in brain circuits mediating nausea.

Conclusions

The results demonstrate that nausea can occur as a premonitory symptom in migraine, independent of pain and trigeminal activation. This is associated with activation of brain structures known to be involved in nausea. We conclude that nausea is a centrally driven symptom in migraine.     

Choanal Atresia: Surgical Management by Hegar’s Dilators

Choanal atresia is one of the more commonly observed congenital abnormalities of the nose. The condition is predominantly found in females with a M:F ratio of 1:2. 65–75 % of patients with choanal atresia are unilateral, and the rest are bilateral. About 50 % of the cases are associated with other congenital anomalies, the most common being coloboma, Heart disease, choanal atresia, mental and growth retardation, genital hypoplasia, ear deformities syndrome. The embryonic origin of choanal atresia is due to persistent bucco-pharyngeal or naso-buccal membrane. Our study was a retrospective study of 14 cases of choanal atresia. All the cases were operated by the first author. Each patient was investigated in detail and recorded by stratifying in sex of patient, age of presentation, type and site of atresia, and associated other congenital anomalies. Patient were operated under general anesthesia and Hegar’s dilators were used to perforate the atretic plate as Hegar’s dilators are believed to have ideal curvature with respect to the sloping contour of the nasal floor. Out of the total 14 cases, 9 (64 %, n = 14) cases were male and 5 (36 %, n = 14) females. The age variations varied from youngest of 3 days to the oldest 31 year old female. Stents were kept for a period of 6–8 weeks and regular follow up nasal endoscopy was done weekly for suctioning and visualizing the size of the airway. There are five different surgical approaches that have been described for surgical treatment of choanal atresia: (1) trans-nasal, (2) trans-palatal, (3) trans-septal, (4) trans-antral and (5) sublabial–transnasal. In our study M:F ratio was 1.8:1 which is comparable Gosepath et al. (Rhinology 45:158–163, 2007) (2:1). In our study bilateral atresia was seen in 43 % (6, n = 14) and unilateral in 57 % (8, n = 14) which is comparable to Newman et al. (44 % bilateral cases, n = 43). Amicable and prompt referral to the ENT surgeon can be of immense value so as to buy adequate time for the surgeon to decide and act as per the patient’s clinical and radiological findings. Hegar’s dilator is passed along the floor of the nose, pushed against the septum so as to avoid penetrating the basal sphenoid.     

Oral cancer databases: A comprehensive review

Cancer database is a systematic collection and analysis of information on various human cancers at genomic and molecular level that can be utilized to understand various steps in carcinogenesis and for therapeutic advancement in cancer field. Oral cancer is one of the leading causes of morbidity and mortality all over the world. The current research efforts in this field are aimed at cancer etiology and therapy. Advanced genomic technologies including microarrays, proteomics, transcrpitomics, and gene sequencing development have culminated in generation of extensive data and subjection of several genes and microRNAs that are distinctively expressed and this information is stored in the form of various databases. Extensive data from various resources have brought the need for collaboration and data sharing to make effective use of this new knowledge. The current review provides comprehensive information of various publicly accessible databases that contain information pertinent to oral squamous cell carcinoma (OSCC) and databases designed exclusively for OSCC. The databases discussed in this paper are Protein‐Coding Gene Databases and microRNA Databases. This paper also describes gene overlap in various databases, which will help researchers to reduce redundancy and focus on only those genes, which are common to more than one databases. We hope such introduction will promote awareness and facilitate the usage of these resources in the cancer research community, and researchers can explore the molecular mechanisms involved in the development of cancer, which can help in subsequent crafting of therapeutic strategies.     

Visible region absorption in TMDs/phosphorene heterostructures for use in solar energy conversion applications

Heterostructures of pristine black phosphorene (P) with transition metal dichalcogenides (TMDs) monolayers of MoS₂, MoSe₂, MoTe₂, WS₂, and WSe₂ are investigated using density functional theory based simulations. The results suggest that individual MoS₂, MoSe₂, MoTe₂, WS₂, WSe₂, and black phosphorene have high absorption in some portions of the visible region (∼390–430 nm) and in the entire ultraviolet (UV) region. All the heterostructures results into redshift phenomena where absorption peaks are seen to shift to lower energies of the spectrum. The absorption coefficient is seen to increase with the wavelength and appears to be shifted towards the red end of the spectrum. High absorption is also observed in the entire visible region (λ ∼ 410 to 780 nm) of the spectrum for all heterostructures. This high absorption in the desired visible range may find many potential applications for the heterostructure, such as in the fabrication of optoelectronic devices and solar cells. The refractive index and dielectric constant of the heterostructure are also calculated and are found to be in line with trends in dielectric constant. Furthermore, it is observed that most of the resultant heterostructures have type-II band alignment which is ideal for solar energy conversion and optoelectronic applications.

Heterostructures of pristine black phosphorene (P) with transition metal dichalcogenide (TMD) monolayers of MoS₂, MoSe₂, MoTe₂, WS₂, and WSe₂ are investigated using density functional theory based simulations.