Kernohan-Woltman notch phenomenon: an exceptional neurological picture?

INTRODUCTION: Ipsilateral hemiparesis (IH) can be defined as a paradoxical dysfunction of the first motor neuron involving the extremities on the opposite side to that expected, given the location of the triggering intracranial pathology. Compression of the corticospinal tract (CSt) along its course through the contralateral cerebral peduncle against the free edge of the tentorium, known as the Kernohan-Woltman notch phenomenon (KWNP), represents the main cause of IH. METHODS: This retrospective study analyses a series of 12 patients diagnosed with IH secondary to KWNP treated at our institution, including a descriptive study of epidemiological, clinical, radiological, neurophysiological, and prognostic variables. RESULTS: In 75% of the cases, symptoms had an acute or subacute onset. Initial imaging studies showed signs of significant mass effect in half of the patients, whereas magnetic resonance imaging (MRI) identified a structural lesion in the contralateral cerebral peduncle in two thirds of them. Impairment of the motor evoked potentials (MEP) was verified in 4 patients. During follow-up 7 patients experienced improvement in motor activity, and near half of the cases were classified in the first three categories of the modified Rankin scale. CONCLUSIONS: In contrast to prior historical series, most of our patients developed a KWNP secondary to a traumatic mechanism. MRI represents the optimal method to identify both the classic cerebral peduncle notch and the underlying structural lesion of the CSt. The use of MEP can help to establish the diagnosis, especially in those cases lacking definite radiological findings.

[Frontal aneurysmal bone cyst. A case report and review of the literature]. / Quiste oseo aneurismatico frontal. Caso clinico y revision de la bibliografia.

INTRODUCTION: Cranial aneurysmal bone cyst (ABC) is a rare pathological finding that is usually diagnosed in young patients. It is defined as a benign lesion made up of intervillous spaces limited by connective bone tissue septa and osteoclast-type giant cells; these histological characteristics are common to extracranial ABC. Clinically, in most patients, they manifest as cranial tumours which may be painful and vary in size. About 100 cases of cranial ABC have been reported in the literature. We present a literature review of the cases of frontal ABC reported to date, including one that was recently treated in our own service. CASE REPORT: A 29-year-old female, with no history of traumatic brain injury, who was examined due to the presence of a fixed, painless frontal cranial lesion on the right-hand side. The results of a radiological study revealed the presence of a lytic cranial lesion with well-delimited edges and marginal sclerosis; peripheral and linear contrast enhancement was also observed in the magnetic resonance imaging of the brain. The patient was submitted to a surgical intervention and the entire lesion was removed. There were no incidents in the post-operative period and the definitive pathological diagnosis was cranial ABC. CONCLUSIONS: Cranial ABC is a pathological condition with well-defined histological and radiological characteristics, despite the fact that its aetiopathogenesis is still not fully understood. Complete excision of the tumour is considered to be the preferred treatment, which often leads to full recovery of the patient and also offers a good long-term prognosis.

How to repair an ischemic brain injury? Value of experimental models in search of answers.

The major aim of experimental models of cerebral ischemia is to study the cerebral ischemic damage under controlled and reproducible conditions. Experimental studies have been fundamental in the establishment of new concepts regarding the mechanisms underlying the ischemic brain injury, such as the ischemic penumbra, the reperfusion injury, the cell death or the importance of the damage induced on mitochondria, glial cells and white matter. Disagreement between experimental and clinical studies regarding the benefit of drugs to reduce or restore the cerebral ischemic damage has created a growing controversy about the clinical value of the experimental models of cerebral ischemia. One of the major explanations for the failure of the clinical trials is the reductionist approach of most therapies, which are focused on the known effect of a single molecule within a specific pathway of ischemic damage. This philosophy contrasts to the complex morphological design of the cerebral tissue and the complex cellular and molecular physiopathology underlying the ischemic brain injury. We believe that the main objective of studies carried out in experimental models of cerebral ischemic injury must be a better understanding of the fundamental mechanisms underlying progression of the ischemic injury. Clinical trials should not be considered if the benefit obtained in experimental studies is limited or weak.

[Cystic hemangioblastoma of the junction of the medulla and upper spinal cord associated to von Hippel-Lindau disease. Two case reports and a review of the literature]. / Hemangioblastoma quistico de la union bulbomedular asociado a enfermedad de von Hippel-Lindau. Presentacion de dos casos y revision de la bibliografia.

INTRODUCTION: Hemangioblastomas are very highly vascularised benign tumours that can present either sporadically or in association with von Hippel-Lindau syndrome in 20% of cases. Only 5-20% of hemangioblastomas are located in the brainstem, and those that occur at the junction of the medulla and upper spinal cord are the ones that are less commonly diagnosed. CASE REPORTS: Two young patients were diagnosed with von Hippel-Lindau disease after beginning with a cystic hemangioblastoma at the junction of the medulla and upper spinal cord as the first pathological manifestation. Both of them underwent a suboccipital craniotomy and the two lesions were completely removed without any kind of post-operative neurological deficits. One of the patients required a reintervention some years later due to a new recurrence of a symptomatic hemangioblastoma in the dorsal medulla. The genetic study conducted in both patients confirmed the presence of a mutation in the VHL gene, which is responsible for the syndrome they were suffering from. CONCLUSIONS: The presence of cystic hemangioblastomas of the junction of the medulla and upper spinal cord associated to von Hippel-Lindau disease is very rare. Despite the technical difficulties involved in removing them, the incorporation of the latest neuroimaging and microsurgery techniques has made it possible to significantly reduce the morbidity and mortality rate associated to the surgical treatment of such patients.

[Experimental models of cerebral ischemia]. / Modelos experimentales de isquemia cerebral.

AIM: To provide a summary of the different experimental models of cerebral ischemia designed both under in vivo and in vitro conditions. A clear and concise description of the specific types of brain lesion reproduced by each model is given together with the most frequent technical troubles associated. DEVELOPMENT: Experimental models of cerebral ischemia have contributed substantially to the understanding of the physiopathology of the ischemic brain injury and to test the beneficial effects of new therapies. Outcome of patients suffering from an ischemic stroke has improved considerably with the use of these models, particularly after the introduction of thrombolytic and neuroprotective drugs. Experimental models allow the study of the evolving ischemic brain injury under strict and controlled conditions. Usefulness of experimental models is limited by their reliability, simplicity and reproducibility among different researchers. Small rodents, especially rats, have been the preferred animals used to develop models of cerebral ischemic injury, due to their cerebral physiology and vascularisation which is closer to the human. CONCLUSION: The use of experimental models of cerebral ischemia constitutes the most suitable tool to investigate the physiopathology of this type of injury. However their simplicity prevents an exact reproduction of the cerebral damage observed in clinical settings. This could be the main reason for the discrepancies observed between the therapeutic effect in the experimental and clinical studies.

[Refractory epilepsy as the presenting symptom of a brucellar brain abscess]. / Epilepsia refractaria como presentacioón de absceso cerebral brucelósico.

INTRODUCTION: Brucellosis is a zoonotic disease that is occasionally transmitted to human beings from infected animal reservoirs. It is an important condition in endemic areas. One infrequent complication of systemic brucellosis is the infection of the central or the peripheral nervous systems. CASE REPORT: A 54-year-old male who was being studied prior to surgery for refractory epilepsy, with clinical expression in the form of complex partial seizures. Neuroimaging findings revealed an expansive lesion in the right temporal lobe, which direct serological, histopathological and microbiological evidence showed to be a chronic brucellar abscess. After combined treatment involving complete surgical resection followed by a cycle of standard antimicrobial therapy, the patient was seizure-free at one year of follow-up. CONCLUSIONS: Despite its low frequency, infection by Brucella must be considered in the differential diagnosis of intracranial expansive lesions, as well as in the case of patients whose presenting symptoms are epileptic seizures. To perform the diagnosis it is especially important to be aware of the wide range of clinical and radiological manifestations that can be produced, and which do not always correlate. Identification of risk factors on the patient record is also a crucial step.

[Reconstruction of thoracolumbar spine instability: clinical and neuroradiological results of a surgical challenge]. / Reconstrucción de la columna toracolumbar inestable: resultados clínicos y neurorradiológicos de un desafío quirúrgico.

INTRODUCTION: Surgical treatment for thoracolumbar union instability represents a challenge, due to the difficult access to this area of the spine, and to the extreme variability of morphological and biomechanical lesions observed. AIM: To describe the indications and clinical and neuroradiological results obtained with procedures of anterior or combined spinal fusion-instrumentation used for the treatment of instable thoracolumbar lesions. PATIENTS AND METHODS: 17 patients with thoracolumbar instability were treated surgically, being followed-up at least for one year. Causes of instability were classified in three groups: (i) fractures or fracture-luxations (n = 7), (ii) pathologic fractures following tumoral invasion (n = 6) and (iii) infectious or degenerative spondylodiscitis (n = 5). In order to carry out the substitution of the injured vertebral body an anterior approach to the thoracolumbar union was performed in all cases, using a modified technique of thoracophrenolaparotomy in which the diaphragmatic dome was not incised. Depending on the number of columns of Denis damaged, the vertebral corpectomy was followed by either an anterolateral or a combined spinal fusion-instrumentation. RESULTS: Pain in standing position was eliminated postoperatively in 83%. Neurological deficits were improved in 50% of cases. Surgical mortality was null and transient postoperative complications occurred in 11.7% of patients, but no lung atelectasis or respiratory infections were observed. CONCLUSIONS: Chronic pain associated to thoracolumbar instability can be treated successfully by substitution of the damaged vertebral body followed by anterior or combined spinal fusion-instrumentation. Thoracophrenolaparotomy without division of the diaphragm is feasible and it reduces the morbidity associated to postoperative respiratory complications.

[Blood brain barrier: development of a structure which supports the functional heterogeneity of the central nervous system]. / La barrera hematoencefalica: desarrollo de una estructura que permite la heterogeneidad funcional del sistema nervioso central.

AIMS: To analyze the functional reasons justifying the existence of the blood brain barrier with an emphasis on its fundamental role supporting neuroglial coupling. DEVELOPMENT: We review in an integrated manner the contributions of different research areas in physiology and metabolism of the central nervous system which allow to understand the functional need for the existence of the blood brain barrier. In particular, we describe the physiological basis of the metabolic functional coupling and the metabolic interactions between neurons and glial cells, two properties directly derived from the presence of the blood brain barrier. Likewise the blood brain barrier is presented as an important determinant of the heterogeneous activation of cerebral tissue as detected by neuroimaging technologies as positron emission tomography and functional magnetic resonance imaging. CONCLUSIONS: The main function of the blood brain barrier is to maintain a stable composition of the extracellular milieu in nervous tissue. This allows the changes in ionic composition and neurotransmitter concentration in the extracellular milieu, to reflect indirectly the generation of action potentials and the state of neurotransmission of neuronal circuits. Glial cells induce the development of the blood brain barrier and are the main sensors of neuronal function, due to their important take up capacity for extracellular potassium and neurotransmitters. Glial homeostasis of the extracellular milieu is circuit specific, limiting the functional metabolic coupling to discrete regions of the brain and generating the classical pattern of heterogeneous activity in the different modules of the nervous tissue.

[Surgical treatment of spondylodiscitis in ankylosing spondylitis. Two cases report]. / Tratamiento quirúrgico de la espondilodiscitis en la espondilitis anquilosante. Presentación de dos casos.

INTRODUCTION: Spondylodiscitis in ankylosing spondylitis has a prevalence of 5%. Mechanical and inflammatory factors are involved in its pathogenesis. Neurosurgical operation is required when neurological complications or vertebral instability occur. Surgery is complicated by the increased fragility of the vertebral column, advanced stage of the disease in many patients, and serious pulmonary complications. CLINICAL CASES: We report two patients who had had ankylosing spondylitis for over 20 years. Both presented complaining of symptoms for several months with lumbar pain and signs of spinal cord lesions. There were signs of discitis and destruction of the adjacent vertebral bodies at T11 T12 and T12 L1 on imaging investigations of the first and second patient respectively. In both cases an anterior approach was used for discectomay and resection of the adjacent vertebral plates. Then an autologous rib graft was done, and anterolateral fixation with plate and screws to the adjacent vertebral bodies. The patients condition improved. Their pain and previous clinical neurological disorder had disappeared by 5 and 1 year later. DISCUSSION AND CONCLUSIONS: The prevalence of patients operated on for spondylodiscitis in the context of ankylosing spondylitis is not known. Dorsolumbar pain with inflammatory characteristics of recent onset in patients with chronic ankylosing spondylitis should lead to suspicion of spondylodiscitis. Although it may be related to previous trauma, discitis is the fundamental mechanism. MR is the most sensitive imaging technique. There may be marked osteoporosis and stenosis of the vertebral canal together with marked ossification of all the paraspinal ligaments. This hinders the approach to the vertebral bodies and their subsequent fixation. Decompression of the vertebral canal using an anterior approach (thoracotomy or thoraco phreno laparotomy) and anterior spinal fixation is the treatment of choice in cases with neurological involvement or involvement of the anterior and medial columns of Denis.