Proton magnetic resonance spectroscopy in childhood brainstem lesions

Background Diagnosis of brainstem lesions in children based on magnetic resonance imaging alone is a challenging problem. Magnetic resonance spectroscopy (MRS) is a noninvasive technique for spatial characterization of biochemical markers in tissues and gives information regarding cell membrane proliferation, neuronal damage, and energy metabolism. Methods We measured the concentrations of biochemical markers in five children with brainstem lesions and evaluated their potential diagnostic significance. Images and spectra were acquired on a 1.5-T imager. The concentrations of N-acetylaspartate, tetramethylamines (e.g., choline), creatine, phosphocreatine, lactate, and lipids were measured within lesions located at the brainstem using Point-resolved spectroscopy sequences. Results Diagnosis based on localized proton spectroscopy included brainstem glioma, brainstem encephalitis, demyelination, dysmyelination secondary to neurofibromatosis type 1 (NF 1), and possible infection or radiation necrosis. In all but one patient, diagnosis was confirmed by biopsy or by clinical follow-up. Conclusions This small sample of patients suggests that MRS is important in the differential diagnosis between proliferative and nonproliferative lesions in patients without neurofibromatosis. Unfortunately, in cases of NF 1, MRS can have a rather misdiagnosis role.     

Multiple pilocytic astrocytomas of the cerebellum in a 17-year-old patient with neurofibromatosis type I

Objective Approximately 10% of patients with neurofibromatosis I (NFI) patients will have central nervous system (CNS) tumors. The most common of these are hypothalamic–optic gliomas, followed by brainstem and cerebellar pilocytic astrocytomas. While isolated pilocytic astrocytomas in NFI are well described, the appearance of multiple pilocytic astrocytomas in an individual patient is less common. The most frequent combination in NFI patients with more than one pilocytic astrocytoma is optic tract/hypothalamic and brainstem. Other combinations are exceedingly rare; multiple pilocytic astrocytomas have only been reported once in the cerebral hemispheres in a patient with NFI. This report presents the first documented case, to our knowledge, of multiple pilocytic astrocytomas in the cerebellum of a patient with NF1. Methods Case report. Conclusion The finding of multiple cerebellar pilocytic astrocytomas in a patient with NF1 is important because it expands the spectrum of presentations for patients with NF1 and also highlights specific diagnostic and therapeutic challenges faced by the treating physicians. The genetic and molecular basis of NF1 is reviewed. Strategies of diagnosis and treatment outlined here are relevant to both patients with NF1 and all patients with multiple posterior fossa tumors.     

Reconstruction of the wrist pseudoarthrosis due to radioulnar fractures with vascularized fibular graft in a child with neurofibromatosis

Nonunion in the forearm following a radioulnar fracture is one of the nightmares of the orthopedic surgeon. Fortunately, it is rare. We treated a large bone defect of the forearm, using a vascularized fibular graft after excision of the unhealed bone segment in a 10-year-old boy with neurofibromatosis. This situation followed a double fracture that had been operated on several times using conventional methods. Following the debridement of the unhealthy tissues in the pseudoarthrotic region, the vascularized fibula was placed on the dorsal surface of the proximal radius fragment. The distal fragment of the radius was inserted into the fibular cavity and fixation was established with a Kirschner wire distally and with a plate proximally. Only two screws were used to fix the plate. The peroneal artery was anastomosed with the radial artery; one of its venae comitantes was anastomosed with the cephalic vein in an end-to-end fashion. After surgery, the elbow was immobilized at 90 degrees of flexion with a splint for 6 weeks. One year after surgery, forearm stabilization and elbow and hand functions were very satisfactory. However, because the distal epiphyses of the bones were destroyed following the repeated surgery and the original trauma itself, a very prominent difference between the two forearms occurred, suggesting the need for bone lengthening in the future. By presenting this case we would like to conclude that one can expect good bone healing with a vascularized bone transfer in these cases when there is not enough space to place screws, but support can be provided by an external splint and K wire.     

Hypercalcemic hyperparathyroidism and hypophosphatemic osteomalacia complicating neurofibromatosis

Summary Neurofibromatosis is sometimes complicated by impaired renal tubular reabsorption of phosphate, hypophosphatemia, and osteomalacia. Hyperparathyroidism has also been reported in patients with neurofibromatosis. When hypercalcemia and elevated levels of parathyroid hormone are found in osteomalacia, however, it may be difficult to determine if the hyperparathyroidism was primary or tertiary. We describe a patient with neurofibromatosis, hypercalcemic hyperparathyroidism, hypophosphatemic osteomalacia, vitamin D deficiency, and clear-cell hyperplasia of all four parathyroid glands. Serial biomechanical, bone biopsy, and densitometric studies confirmed that treatment with ergocalciferol, calcium, and phosphate supplements significantly improved the osteomalacia but caused increased parathyroid overactivity. After subtotal parathyroidectomy, the parathyroid hormone concentration became normal and the bone mineral content increased at the spine and hip, but inappropriate phosphaturia persisted. The findings indicate that hyperparathyroidism, osteomalacia, and vitamin D deficiency adversely affect each other.     

Spontaneous hemothorax associated with von Recklinghausen''s disease

Spontaneous hemothorax is a rare and life threatening complication of neurofibromatosis. Two types of vascular involvement have been described: (a) stenotic or aneurysmal alterations in large vessels such as the aorta and its branches; and (b) dysplastic features in smaller vessels. Thoracotomy and surgical ligation of the bleeding vessels is primarily indicated in the presence of active bleeding with associated hemodynamic compromise. A more conservative approach with endovascular embolization or non-operative management have also been reported in case of hemodynamic stability. We present a rare case of spontaneous hemothorax treated conservatively in a patient with von Recklinghausen's disease.     

Malignant evolution of presumed benign lesions in the brain in neurofibromatosis: case report

We report a patient suffering from neurofibromatosis type 1 in whom neoplasms developed from the areas of altered signal which are generally considered benign and typical of the disease. MRI, despite two previous examinations 3 and 2 years before development of the tumour, gave no clue to an unfavourable outcome. Received: 18 January 1996 Accepted: 24 October 1996     

Spontaneous regression of optic pathways gliomas in three patients with neurofibromatosis type I and critical review of the literature

Case reports The authors report their experience about three children (two girls, one boy; average age 1.6 years) with a spontaneous regression of optic gliomas. All of them had a previous diagnosis of neurofibromatosis type 1 (NF 1). None of them underwent surgery or biopsy nor received chemotherapy or radiotherapy. The complete regression was documented by MRI scans performed during a mean follow-up of 6.3 years.Literature review Moreover, the authors analyze the features of the 16 cases previously reported in English literature of spontaneously regressed optic gliomas with an overview of the different therapeutic strategies. The knowledge that this kind of tumor, particularly in young patients, may regress is important in the decision of the best therapeutic approach.     

Neurogenic polyps

A neoplastic proliferation of peripheral nerve sheath cells (Schwann cells, fibroblasts and perineurial cells) and ganglion cells in the colorectum may give rise to the mucosal or submucosal polyps. Depending upon the predominant cell types, these neurogenic polyps can be classified as schwannomas, granular cell tumours, neurofibromas, perineuriomas, mixed nerve sheath tumours, ganglioneuromas or paragangliomas. Morphologically, the neoplastic cells repeat or mimic the corresponding nerve sheath cells or neurons in terms of growth pattern, histology and immunoreactivity. They are uncommon, but the polyps can occur in any age group, although the vast majority of patients are adults. The polyps can be either solitary (most peripheral nerve sheath tumours) or multiple, especially if associated with systemic diseases (i.e. syndromes involving the peripheral nerve tissue). They are usually incidental findings or may be accompanied by gastrointestinal symptoms. Almost all colorectal neurogenic polyps are benign, and they rarely undergo malignant transformation unless they are part of a syndromatic manifestation. However, these polyps may cause a diagnostic problem during screening for colorectal cancer. An accurate diagnosis of these entities will help clinicians to make appropriate management decisions.     

Resolution of spinal epidural vascular pseudotumor following balloon occlusion of a postoperative vertebral arteriovenous fistula

Summary We describe a case of a vascular mass arising secondary to a postoperative vertebral arteriovenous fistula mimicking recurrent cervical neurofibroma on CT in a patient with neurofibromatosis. Angiography was required for diagnosis. The recurrent tumor resolved following balloon embolization of the fistula.     

多道听觉脑干植入的临床应用

目的　探讨多道听觉脑干植入的手术方法及其对恢复双侧听神经瘤所致全聋患者听力的效果。方法　 7例双侧听神经瘤患者 ,在肿瘤摘除后将 2 1道听觉脑干植入 (auditorybrainstemimplant,ABI)电极植入于第四脑室外侧隐窝内 ,直接刺激脑干耳蜗核 ,术中以面神经电图、舌咽神经肌电图及电诱发听觉脑干反应 (electricallyevokedauditorybrainstemresponses,EABR)确定电极的正确位置。术后 6周开通装置并调试 ,定期行言语识别能力测试。结果　 6例患者术中均能准确定位外侧隐窝 ,并能记录到典型的EABR ;术后均能获得不同程度的言语识别能力 ,其中 2例获得开放句识别能力。另 1例患者术中解剖定位困难 ,术中未能记录到EABR。术后电极刺激 1例无非听觉反应、5例部分电极产生非听觉反应、1例全部电极均产生非听觉反应 ,有非听觉反应的相应电极被关闭。结论　多道听觉脑干植入能使因双侧听神经瘤而全聋的患者产生有意义的听觉 ,术中正确定位脑干耳蜗核为手术成功的关键。