Evaluation of the retrosigmoid approach for fourth nerve neuroma excision

Schwannomas originating from the trochlear nerve without neurofibromatosis are extremely rare. Thirty four cases have previously been reported in the literature, and only 25 cases were pathologically diagnosed, five of them had a large cystic component and a smaller solid portion. Complex skull base approaches have been usually applied for their removal. The aim was to report two cases of trochlear schwannomas operated in the international neuroscience institute in Hannover, Germany. This is a retrospective report on two cases of trochlear schwannomas operated in the international neuroscience institute in Hannover, Germany, first case was a 62 years old female patient who presented to us complaining of, decreased hearing on the right ear and decreased sensation over the right side of the face, with vertigo gait instability for more than one year. The magentic resonance imaging examination revealed an intensely enhancing well circumscribed 3 cm large extra axial lesion, compressing the brain stem at the lower midbrain and upper pons level. Second case was a 49 years old female with long history of trigeminal neuralgia attacks, with a failed medical treatment for such problem. Lately one year ago she started to complain of hearing difficulty on the left ear, with decreased of the trigeminal pain with decreased sensation on the left side of the face which was attributed to the trigeminal ganglion block done one year ago Magnetic resonance imaging revealed a 2.5 cm left sided extra axial lesion compressing the brain stem at the lower midbrain and upper pontine level. Total resection was performed via a retrosigmoid craniotomy appraoach. In the two cases the trochlear nerve was fanned out and unified with the tumor. The tumor was diagnosed as a schwannoma. The Retrosigmoid approach is a safe surgical approach for removal of the trochlear schwannomas in comparison to the other surgical approaches. Total tumor removal without additional morbidity can be achieved through that approach, especially for lesions in the middle incisural space can be safely removed via the retrosigmoid approach. The gradual development of trochlear nerve palsy is well compensated for by other extraocular muscles. Normal vision is not impaired or returns soon postoperatively

Ultraestructura del ganglio trigémino en la esquizofrenia: primeros resultados / Ultraestructure of the trigeminal ganglion in schizophrenia: first results

La posibilidad de que el ganglio trigémino constituya un primer escalón en la diseminación del virus herpes simplex hominis tipo 1 (HSV1) al sistema nervioso central es una evidencia demostrada en trabajos experimentales en animales. La proximidad anatómica del ganglio de Gasser a estructuras del sistema límbico hace de este ganglio una localización clave en la extensión de un agente infeccioso a otras estructuras vecinas especialmente en el caso del HSV1. El ganglio de Gasser constituye un reservorio de la forma latente del HSV1 en personas normales. En la esquizofrenia –donde hay déficit en la respuesta inmunológica– aumentaría más la posibilidad de que se favorezca una afectación del complejo amígdala-hipocampo por este virus. Los genes, las situaciones de estrés y los cambios hormonales de la pubertad pudieran actuar como factores desencadenantes en este proceso de interacción virus-célula nerviosa. A pesar de todos los elementos señalados no existe en la literatura médica especializada ninguna publicación en donde se refiera haber estudiado el ganglio trigémino en la esquizofrenia por técnicas ultraestructurales. En el presente trabajo se presentan los primeros resultados del estudio ultraestructural post-mortem de este ganglio en una paciente esquizofrénica paranoide fallecida por causa no infecciosa del sistema nervioso central. Los resultados obtenidos mediante técnicas inmuno-electromicroscópicas demostraron la presencia de antígeno de HSV1 en las muestras estudiadas de este ganglio, las que tenían características similares a las observadas en esquizofrénicos adultos fallecidos, en fetos de madres esquizofrénicas y en animales experimentalmente inoculados con líquido cefalorraquídeo (LCR) de pacientes esquizofrénicos.

The possibility that the trigeminal ganglia constitutes a first step in the dissemination of the herpes simplex hominis type 1 virus (HSV1) to the central nervous system is an evidence demonstrated in experimental works in animals. The anatomical vicinity of the ganglion of Gasser to structures of the limbic system makes a key localization of this ganglion in the extension of an infectious agent to other neighbouring structures especially in the case of the HSV1. The ganglion of Gasser constitutes a reservoir in the latent form of the HSV1 in normal people. In schizophrenia, –where there is deficit in the immunologic response– it would increase more the possibility of an affectation of the amygdala hippocampus complex by this virus. Genes, stress situations and the puberty hormonal changes could act as break loose factors in this process of virus nervous cell interaction. In spite of all the pointed out elements any publication exist in the specialized medical literature where refers to have studied the trigeminal ganglia in schizophrenia by ultrastructural techniques. In the present work the first results of a post-mortem ultrastructural study of this ganglion of a paranoid schizophrenic patient deceased of non central nervous system infectious cause is presented. The results obtained by means of immuno-electronmicroscopic techniques demonstrated the presence of HSV1 antigen in the studied samples of this ganglion those that had similar characteristics to those observed in dead adults schizophrenics, foetuses from schizophrenic mothers and experimental animals inoculated with cerebrospinal fluid from schizophrenic patients.