Longevity of batteries in internal pulse generators used for deep brain stimulation

The longevity of batteries in internal pulse generators (IPGs) used clinically for deep brain stimulation is not known. We conducted a study to assess the life span of these batteries. From 1993 to 2000, 163 single-channel batteries were surgically implanted in our institution. The electrical settings utilized in patients who had battery failures were assessed and the total electrical energy delivered (TEED) was calculated and correlated with battery longevity. Fourteen IPGs had battery failure requiring replacement. The median life span of the batteries was 45 months. Batteries with high energy consumption as assessed by TEED had a reduced life span (r = -0.82, p < or = 0.001). Patients with essential tremor who required battery replacement needed higher settings to control their symptoms and therefore presented a shorter battery life when compared to patients with Parkinson's disease. In our series of patients who needed battery replacement, battery longevity varied with stimulation parameters but was longer than expected from the manufacturer's specifications.     

Allorecognition and effector pathways of islet allograft rejection in normal versus nonobese diabetic mice

Islet transplantation is becoming an accepted therapy to cure type I diabetes mellitus. The exact mechanisms of islet allograft rejection remain unclear, however. In vivo CD4(+) and CD8(+) T cell-depleting strategies and genetically altered mice that did not express MHC class I or class II antigens were used to study the allorecognition and effector pathways of islet allograft rejection in different strains of mice, including autoimmunity-prone nonobese diabetic (NOD) mice. In BALB/c mice, islet rejection depended on both CD4(+) and CD8(+) T cells. In C57BL/6 mice, CD8(+) T cells could eventually mediate islet rejection by themselves, but they produced rejection more efficiently with help from CD4(+) T cells stimulated through either the direct or indirect pathway. In C57BL/6 mice, CD4(+) T cells alone caused islet rejection when only the direct pathway was available but not when only the indirect pathway was available. In contrast, in NOD mice, CD4(+) T cells alone, with only the indirect pathway, could mediate islet and cardiac allograft rejection. These findings indicate that different mouse strains can make use of different pathways for T cell-mediated rejection of islet allografts. In addition, they demonstrate that NOD mice, which develop autoimmunity and are known to be resistant to tolerance induction, have an unusually powerful CD4(+) cell indirect mechanism that can cause rejection of both islet and cardiac allografts. These data shed light on the mechanisms of islet allograft rejection in different responder strains, including those with autoimmunity.     

Bispectral index in a 3-year old undergoing deep hypothermia and circulatory arrest

We report a 3-year-old girl who presented with Scimitar syndrome and underwent hypothermic circulatory arrest for correction of anomalous pulmonary veins and an atrial septal defect. In this case the Bispectral Index (BIS) correlated significantly with the gradual onset of hypothermia and circulatory arrest. However, BIS remained low during the rewarming phase of cardiopulmonary bypass, in spite of adequate pump flows and stable haemodynamics. We postulate that this significant lag in BIS during the rewarming phase of deep hypothermic circulatory arrest may represent neuronal bewilderment or perhaps stunning, and differs from previous studies that show significant increase in BIS during rewarming from mild hypothermia.     

Cutaneous signs

Cutaneous signs play a significant role in clinical medicine. Signs have often been named after the initial observer. They may indicate either dermatologic or systemic illness and aid the examiner in diagnosis and relevant investigations. Some are specific, some have been described in other conditions, and few have lost their relevance. Most of the signs are related to the pathogenesis of the disease but the cause of some is not clear.     

Epidermoid cyst radiologically mistaken as a left sided subpulmonic effusion

A 33-year-old female had a left sided chest pain for the last 3 months. Chest X-ray showed a left basal opacity. Computed tomography chest suggested a left sided subpulmonic effusion (17.5x12.2x13 cm) with thick enhanced walls with marked collapse of the left lower lobe and displacement of the heart and mediastinum to the right side. Trial of thoracocentesis was done and it was positive. Trial of intercostal tube insertion was done with a sense of very thick pleura and the patient developed a vasovagal attack. Accordingly, exploratory thoracotomy was decided. Intraoperative assessment showed a huge anterosuperior mediastinal cyst attached to the pericardium and was successfully resected. The pathological findings were compatible with epidermoid cyst.     

Free vascularized fibula graft for a cystic femoral head and neck lesion in the West Indies

A case is presented of an 18-year-old athlete with fibrous dysplasia of the femoral neck and head. The approach was by joint plastic and orthopaedic teams, which minimized operating time and allowed the option of vascular bone grafting. The lesion was curetted through a greater trochanteric window and the defect reconstructed with a free vascularized fibula graft with excellent result. Weight bearing was achieved in six months and there was minimal donor site morbidity. We believe the free vascularized fibula graft to be a reconstructive option, in difficult orthopaedic problems, facilitated by microsurgery and there is immense benefit of a joint effort between the orthopaedic and plastic surgical teams.     

Percutaneous endoscopic gastrostomy in Trinidad and Tobago

Percutaneous endoscopic gastrostomy tube placement is rapidly becoming the preferred method of gastrostomy tube placement. We describe our experience with this procedure in nine patients. The main complications were minor and due to local infection. This report demonstrates the simplicity and safety of this technique.