Revisão de anatomia e correlações clínicas do tronco encefálico, parte i: bulbo / Review of brain anatomy and clinical correlations, part i: medulla

O Tronco encefálico (TE) é uma estrutura singular do sistema nervoso central, pois nele passam tratos sensoriais ascendentes da medula espinal, tratos sensoriais da cabeça e do pescoço, os tratos descendentes motores originados no prosencéfalo (divisão mais rostral do encéfalo), e as vias ligadas aos centros de movimento dos olhos. Contém ainda os núcleos dos nervos cranianos e está envolvido na regulação do nível de consciência através de projeções ao prosencéfalo oriundas da formação reticular. Todas essas estruturas coexistem em um espaço muito exíguo, o que faz com que o TE seja um local muito sensível às alterações patológicas, sendo que os pacientes apresentam muitos sinais neurológicos mesmo com lesões muito pequenas nesse local. Compreender a anatomia interna do TE é essencial para o diagnóstico neurológico e a prática da medicina clínica. Outros profissionais da saúde também se beneficiam desse conhecimento para melhor manejo dos seus pacientes neurológicos. Essa revisão apresenta detalhes da anatomia macroscópica e microscópica do bulbo, bem como seus correlatos clínicos frente às lesões mais comuns dessa divisão particular do TE, conhecidas como síndromes bulbares.

The brainstem is a unique structure in the central nervous system, since it gives way to ascending sensory tracts from the spinal cord, sensory tracts from the head and neck, motor descending tracts originating from the forebrain, and the pathways connected to the eye movement centers. It also contains the cranial nerve nuclei and is involved in the regulation of consciousness levels through projections to the forebrain originating in the reticular formation. All these structures coexist in a very small space, which makes the brainstem very sensitive to pathological changes, with patients presenting several neurological symptoms even with very small brainstem lesions. Understanding the internal anatomy of the brainstem is essential for neurological diagnosis and the practice of clinical medicine. Other health professionals also benefit from this knowledge to better manage their neurological patients. This review presents detailed information on the macroscopic and microscopic anatomy of the medulla, as well as its clinical correlates in the face of the most common lesions of this particular division of the brainstem, known as medullary syndromes.

Microsurgical Resection of a Left Cerebral Peduncle Cavernous Malformation: 3-Dimensional Operative Video.

Brainstem cavernous malformations are challenging lesions considering the numerous eloquent structures frequently related. Surgical resection is the preferred treatment if the patient is symptomatic and the lesion can be safely resected. We present the case of a right-handed 38-yr-old female, presenting with progressive impairment of her handwriting. Physical examination showed a right-sided grade 4/5 hemiparesis. Preoperative imaging was suggestive of a left cerebral peduncle cavernous malformation with a recent area of hemorrhage. The most superficial portion of the lesion was on the surface of the brainstem in the supratrigeminal safe entry zone of the pons. A frontotemporal craniotomy was performed, followed by a pretemporal transtentorial approach. Prior to performing brainstem incision, the area was stimulated, and no motor evoked potential was recorded. The hematoma was then evacuated, and the cavernous malformation was dissected and removed. The capsule was also dissected and removed, using neurophysiological monitoring to guide this procedure. The lesion was completely resected, and the patient was discharged on postoperative day 7 with a right-sided hemiparesis grade 3/5, which improved to grade 5/5 after 4 mo. The patient presented an improvement of her symptoms, with no new neurological deficits. Brainstem cavernomas can be safely removed in selected cases, using the adequate safe entry zone and the appropriate surgical approach. The pretemporal route can be used to reach the anterolateral aspect of the upper part of the brainstem, as it combines the advantages of both transsylvian and subtemporal approaches. An informed consent was obtained from the patient for publication of this operative video.

Kernohan-Woltman Notch Phenomenon ­ Case Report

The Kernohan-Woltman notch phenomenon is a paradoxical neurological manifestation consisting of a motor deficit ipsilateral to a primary brain injury. It has been observed in patients with brain tumors and with supratentorial hematomas. It is considered a false localizing neurological sign. Magnetic resonance imaging (MRI) scan has been the test of choice. The recognition of this phenomenon is important to prevent a surgical procedure on the opposite side of the lesion. The present case report describes a case of chronic subdural hematoma with a probable finding of the Kernohan-Woltman phenomenon, and it discusses its pathophysiology, imaging findings, treatment, and prognosis.

Collagenous choristoma at the cerebellar peduncle of a Nelore bull / Coristoma colagenoso em pedúnculo cerebelar de um bovino Nelore

Choristomas are mature normal tissues in abnormal anatomical positions. Reports in domestic animals are uncommon to rare, usually restricted to cattle, with the proliferation of different tissues in various locations, such as subcutaneous tissue, thoracic cavity, retroperitoneal and ocular regions. No age range is predominantly affected, but there are more reports in young cattle. The Laboratory of Veterinary Pathology at the Universidade Federal do Rio Grande do Sul received a brainstem sample of a bull, Nelore breed, 5 years old, from the project of Supplementary Diagnostic Methods of Transmissible Spongiform Encephalopathies (TSEs). The animal presented recumbency at the time of slaughter; was alert, with a complete fracture to the right femur and without neurological signs. On gross examination, there was a white oval firm mass, located caudally to the left caudal colliculus, on the left cerebellar peduncle. In the microscopic examination, there was a well-demarcated area, unencapsulated and composed predominantly of connective tissue fibers (collagen). Immunohistochemical examination for glial fibrillary acidic protein was negative. Due to the gross and microscopic characteristics, a diagnosis of collagenous choristoma at the cerebellar peduncle was established, since the presence of collagen within the brain tissue itself is abnormal.

Coristomas são tecidos normais maduros e posições anatômicas anormais. Relatos em animais domésticos são incomuns a raros, restringindo-se geralmente à espécie bovina, com proliferação de diferentes tecidos em várias localizações, como tecido subcutâneo, cavidade torácica, região retroperitoneal e ocular. Não há uma faixa etária predominantemente afetada, porém há mais relatos em bovinos jovens. O Laboratório de Patologia Veterinária da Universidade Federal do Rio Grande do Sul recebeu uma amostra de tronco encefálico de um bovino Nelore, macho, cinco anos de idade, vinculado ao projeto de Complementação de Métodos Diagnósticos de Encefalopatias Espongiformes Transmissíveis (EETs). O animal apresentava-se no momento do abate em decúbito; estava alerta, com uma fratura completa no fêmur direito e sem sinais neurológicos. No exame macroscópico, observou-se uma massa branca oval, firme, localizada caudalmente ao colículo caudal esquerdo, sobre o pedúnculo cerebelar esquerdo. No exame microscópico, observou-se uma área bem delimitada, não encapsulada, composta predominantemente por fibras de tecido conjuntivo fibroso (colágeno). O exame imuno-histoquímico para proteína ácida fibrilar glial foi negativo. Devido às características macroscópicas e microscópicas, o diagnóstico de coristoma colagenoso foi estabelecido, visto que a presença de colágeno no encéfalo é anormal.

Collagenous choristoma at the cerebellar peduncle of a Nelore bull / Coristoma colagenoso em pedúnculo cerebelar de um bovino Nelore

Choristomas are mature normal tissues in abnormal anatomical positions. Reports in domestic animals are uncommon to rare, usually restricted to cattle, with the proliferation of different tissues in various locations, such as subcutaneous tissue, thoracic cavity, retroperitoneal and ocular regions. No age range is predominantly affected, but there are more reports in young cattle. The Laboratory of Veterinary Pathology at the Universidade Federal do Rio Grande do Sul received a brainstem sample of a bull, Nelore breed, 5 years old, from the project of Supplementary Diagnostic Methods of Transmissible Spongiform Encephalopathies (TSEs). The animal presented recumbency at the time of slaughter; was alert, with a complete fracture to the right femur and without neurological signs. On gross examination, there was a white oval firm mass, located caudally to the left caudal colliculus, on the left cerebellar peduncle. In the microscopic examination, there was a well-demarcated area, unencapsulated and composed predominantly of connective tissue fibers (collagen). Immunohistochemical examination for glial fibrillary acidic protein was negative. Due to the gross and microscopic characteristics, a diagnosis of collagenous choristoma at the cerebellar peduncle was established, since the presence of collagen within the brain tissue itself is abnormal.(AU)

Coristomas são tecidos normais maduros e posições anatômicas anormais. Relatos em animais domésticos são incomuns a raros, restringindo-se geralmente à espécie bovina, com proliferação de diferentes tecidos em várias localizações, como tecido subcutâneo, cavidade torácica, região retroperitoneal e ocular. Não há uma faixa etária predominantemente afetada, porém há mais relatos em bovinos jovens. O Laboratório de Patologia Veterinária da Universidade Federal do Rio Grande do Sul recebeu uma amostra de tronco encefálico de um bovino Nelore, macho, cinco anos de idade, vinculado ao projeto de Complementação de Métodos Diagnósticos de Encefalopatias Espongiformes Transmissíveis (EETs). O animal apresentava-se no momento do abate em decúbito; estava alerta, com uma fratura completa no fêmur direito e sem sinais neurológicos. No exame macroscópico, observou-se uma massa branca oval, firme, localizada caudalmente ao colículo caudal esquerdo, sobre o pedúnculo cerebelar esquerdo. No exame microscópico, observou-se uma área bem delimitada, não encapsulada, composta predominantemente por fibras de tecido conjuntivo fibroso (colágeno). O exame imuno-histoquímico para proteína ácida fibrilar glial foi negativo. Devido às características macroscópicas e microscópicas, o diagnóstico de coristoma colagenoso foi estabelecido, visto que a presença de colágeno no encéfalo é anormal.(AU)