Primary cerebellopontine angle melanocytoma: review.

Introduction Primary cerebellopontine angle melanocytomas (PCPAMs) are very rare. Their natural history and prognosis are not fully understood. We reviewed the literature and add a new case to analyze PCPAM's presentation, radiological features, and outcome of treatment. Methods We performed a literature review using Medline, Embase, PubMed, and Cochrane databases. We searched for melanocytoma, melanoma, and pigmented tumors in the posterior cranial fossa and CPA to identify PCPAM. We have also searched our institution's neuro-oncology database. Results We identified 23 PCPAM from the literature and one case of our own. The mean age at presentation was 44.4 years with slight male preponderance. PCPAM presented with cerebellopontine angle (CPA) syndrome with or without hydrocephalus. Preoperative diagnosis was difficult; they appeared hyperintense on T1 and isointense on T2 magnetic resonance imaging (MRI) and enhanced with gadolinium. However, the final diagnosis was only made by immunohistochemical examination. Total surgical resection of PCPAM was associated with prolonged survival while subtotal excision was associated with frequent recurrence. Conclusion PCPAM are very rare and should be considered in the differential diagnosis of all CPA lesions that appear hyperintense on T1 and isointense on T2 MRI images. Patients with PCPAM should undergo total surgical resection to avoid fatal recurrences

Asphericity and finiteness for certain group presentations

We study diagrammatic reducibility for the relative group presentations Rn(k, l, ε) = H, x | t 3 x k t 2 x ε(k+l) where H = t | t n , n ≥ 7, k ≥ 1, l ≥ 0 and ε = ±1. We apply our results to classify finiteness for the group Gn(k, l, ε) defined by Rn(k, l, ε) apart from the two exceptional cases (n, k, l, ε) = (7,2,1,-1) and (9,1,1,-1)

Equations over groups

If G is a none trivial group and t is an element distinct from G then r(t) =g_1 t^l_1 …......g_kt^l_k= 1 , k ≥1, g_i in G\{1}, l_i in Z\{0} is said to be an equation over G. There has been much research aimed to investigate solvability of such equations over groups and these researches adopted two main approaches. The first considers the properties of G. The other direction which we are following here is to put restrictions on r(t). The results obtained in this direction was of length restriction at first. More resent more results have been obtained and the concept of isolated t-exponent has been introduced and used to study a generalized form of equations of unlimited length. In this study we investigate r(t) which has the generalized form w_1t^l_1w_2t^l_2w_3t^l_3w_4t^l_4 where w_i = g_{i,1} t^m_{i,1} .....t^m_{i,k_i-1}g_{i,k_i}. In Chapter 1 we introduce the concept of equations over groups and we give some of the known results and the geometric method of proof is explained. We also state our main theorem and the main lemma which will be proved in the following chapters and some technical lemmas are proved. In Chapter 2, Chapter 3, and Chapter 4 the Cases I, II, III are discussed and the distribution is shown. In Chapter 5 the main lemma is proved and the proof of the main theorem is completed

The role of women in establishing and developing small business projects, and their participation in the development process: A field study of a group of small business projects in Libya

Small business projects are an important aspect of the structure of the Libyan economy. It has recently appeared that there is a real trend towards economic reform and diversification of income sources, apart from the main source of income which is oil. Using human capital theory, this study aims to identify the role played by Libyan women in establishing and developing small businesses and the extent to which such projects contribute to supporting the development process. It highlights the impact of culture and religion as main barriers to Libyan women starting their own businesses. This study uses mixed methods. Ninety-five Libyan female business owners participated in the questionnaire. The results show that there is a lack of follow-up from the financing authorities. There were difficulties and challenges in relation to training, internal and external competition, professional technological management, and materials. Participants in qualitative research state that the main reasons for choosing to run their own businesses are that they give them the opportunity to show their inventions, express their ideas, and display their talents. Some believe that small business projects in Libya enable them to gain access to international markets, owing to their relative advantage and unique traditional peculiarity. Concerning obstacles Libyan women face when establishing their small business projects, participants declare that the obstacles were mainly financial, cultural, there is also a lack of government support and weak infrastructure in all Libyan cities. Women believe that the opportunities to engage in business are enough and available for Libyan women but it needs more care and attention from the competent authorities. This study contributed to the literature through the justification of the phenomenon and the ability to overcome the limitation that women face when starting their own businesses. Moreover, it also fills part of the gap in the literature by identifying the types of small business projects within the Libyan economic sectors that are either neglected or conflated in previous studies. The study has specific implications for researchers and practitioners

1H MR Spectroscopy in Gliomatosis: Is there a Sensitivity Issue?

Objective. 1H MR spectroscopy (MRS) is widely performed for assessment of brain tumours and is considered a highly sensitive technique capable of differentiating benign from malignant conditions and tumour grading. Method. We present a case of a 69 year old woman who was suspected to have gliomatosis on MRI. Results. MRS performed using single voxel and chemical shift/multivoxel techniques was within normal limits. A repeat scan 6 months later showed progressive disease, and biopsy was performed that proved the diagnosis of glioblastoma. Conclusion. Normal MRS in a patient with suspicion of gliomatosis on MRI should not reassure clinicians into assuming a benign aetiology or a good prognosis in short term

Evaluation of Thiel cadaveric model for MRI-guided stereotactic procedures in neurosurgery

BACKGROUND: Magnetic resonance imaging (MRI)-guided deep brain stimulation (DBS) and high frequency focused ultrasound (FUS) is an emerging modality to treat several neurological disorders of the brain. Developing reliable models to train and assess future neurosurgeons is paramount to ensure safety and adequate training of neurosurgeons of the future. METHODS: We evaluated the use of Thiel cadaveric model to practice MRI-guided DBS implantation and high frequency MRI-guided FUS in the human brain. We performed three training sessions for DBS and five sonications using high frequency MRI-guided FUS in five consecutive cadavers to assess the suitability of this model to use in training for stereotactic functional procedures. RESULTS: We found the brains of these cadavers preserved in an excellent anatomical condition up to 15 months after embalmment and they were excellent model to use, MRI-guided DBS implantation and FUS produced the desired lesions accurately and precisely in these cadaveric brains. CONCLUSION: Thiel cadavers provided a very good model to perform these procedures and a potential model to train and assess neurosurgeons of the future