Imaging the nigrostriatal system to monitor disease progression and treatment-induced complications.

Radiotracer imaging (RTI) techniques such as positron emission tomography (PET) allow the in vivo assessment of nigrostriatal DA function in Parkinson's disease and have provided valuable insights into the mechanisms of nigrostriatal degeneration and the consequent compensatory changes. Moreover, functional imaging serves as an excellent tool in the assessment of the progression of PD and the evolution of treatment-related complications. However, various studies have shown discordance between clinical progression of PD and nigrostriatal degeneration estimated by PET or SPECT, and no RTI technique can be reliably used as a biomarker for progression of PD. Presynaptic dopaminergic imaging has consistently demonstrated an anterior-posterior gradient of dopaminergic dysfunction predominantly affecting the putamen, with side-to-side asymmetry in tracer binding. Dopaminergic hypofunction in the striatum follows a negative exponential pattern with the fastest rate of decline in early disease. Evaluation of central pharmacokinetics of levodopa action by PET has demonstrated the role of increased synaptic dopamine turnover and downregulation of the dopamine transporter in the pathophysiology of levodopa-induced dyskinesias. In PD with behavioral complications such as impulse control disorders, increased levels of dopamine release have been observed in the ventral striatum during performance of a positive reward task, as well as loss of deactivation in orbitofrontal cortex in response to negative reward prediction errors. This suggests that there is a pathologically heightened "reward" response in the ventral striatum together with loss of the capacity to respond to negative outcomes. Overall, functional imaging with PET is an excellent tool for understanding the disease and its complications; however, caution must be applied in interpretation of the results.

The nature and time course of cortical activation following subthalamic stimulation in Parkinson's disease.

We studied the time course and nature of interactions between the subthalamic nucleus (STN) and the motor cortex in 8 Parkinson disease (PD) patients with chronically implanted STN deep-brain stimulation (DBS) electrodes. We first identified the cortical evoked potentials following STN stimulation. The most consistent potential was positive wave with peak latency of 22.2 +/- 1.2 ms from stimulation of clinically effective contacts. We then stimulated the motor cortex with transcranial magnetic stimulation (TMS) at 2-15 ms and at the latency of the evoked potential ( approximately 23 ms) following STN DBS. TMS induced currents in 3 directions: lateral-medial (LM) direction activated corticospinal axons directly, posterior-anterior (PA), and anterior-posterior (AP) directions activated corticospinal neurons transynaptically. Motor-evoked potentials (MEP) elicited by AP and PA TMS were facilitated at short (2-4 ms) and medium latencies (21-24 ms). However, MEPs elicited by LM TMS were not modified by STN DBS. Short-latency antidromic stimulation of the corticosubthalamic projections and medium latency transmission likely through the basal ganglia-thalamocortical circuit led to cortical evoked potentials and increased motor cortex excitability at specific intervals following STN stimulation at clinically effective contacts. Cortical activation may be related to the clinical effects of STN DBS in PD.

Scleredema Diabeticorum with unusual presentation and fatal outcome.

We present a case of Scleredema Diabeticorum (SD) in a patient with diabetic neuropathy and restrictive respiratory disease with unusual skin lesion distribution. The onset of dermatologic symptoms heralded a progressive respiratory disease with constrictive component. Painful diabetic neuropathy was noteworthy and difficult to relieve. Predominantly, distribution of the skin lesions on the thighs makes the case exceptional. T2-weighted MRI showed abnormal hyperintensities along the muscles of the thighs in correspondence with the skin lesions. Gait and respiratory symptoms progressively worsened. After a transient remitting period, he developed sudden shortening of breath, arrested and expired at home.The atypical distribution of the skin lesions with further involvement of underlying muscles plus concomitant polyneuropathy and respiratory constrictive disease with sudden death is quite unusual and aggressive presentation of SD.

Anesthetic management of autoimmune polyglandular syndrome (Schmidt's syndrome)--a case report-.

BACKGROUND: Autoimmune polyglandular syndromes (APS) are complex diseases with diverse clinical presentations resulting from involvement of multiple endocrine glands. Surgery under anesthetic in these patients is challenging. A case of Schmidt syndrome (autoimmune polyglandular syndrome type 11) that developed adrenocortical insufficiency in the postoperative period is reported. Etiology, pathogenesis, types and anesthetic problems associated with these cases are discussed. CASE REPORT: A 41 yr old female patient, diagnosed to have APS (Schmidt syndrome) presented for uterine surgery. She had autoimmune glandular involvement of pituitary, thyroid, parathyroid, adrenals and melanocytes and was on hormone replacements for the deficiencies incurred, which were continued till the morning of surgery. Surgery was conducted under general anesthetic combined with epidural analgesia. In spite of supplementation of steroid in physiological doses prior to surgery, she developed hemodynamic instability in the early postoperative period, but could be successfully resuscitated with additional steroid dosage and fluids. CONCLUSION: This patient presented with multiglandular endocrine involvement necessitating timely, adequate hormone replacement and appropriate fluid management. These challenges require careful approach to anesthetic management.

Fibre-optic intubation in oncological head and neck emergencies.

OBJECTIVE: Although fibre-optic bronchoscopic intubation is well recognized as the most valuable adjunct for elective management of the difficult airway its precise role in oncological head and neck emergencies has not been evaluated. The objective of this study was to evaluate the role of fibre-optic intubation in such emergencies. METHODS: This was a consecutive case series study by a single surgeon (the otolaryngologist) and anaesthetist team, taking place in a regional tertiary-referral head and neck surgical oncology centre. A series of 17 consecutive oncological head and neck emergency patients underwent fibre-optic intubation with a Portex endotracheal tube of inner diameter > or =7 mm, with the aid of a 6-mm (EB-1830T2) Pentax fibre-optic video bronchoscope. The study assessed occurrence of: avoidance of tracheostomy in bleeding emergencies; a well placed, uncomplicated tracheostomy in airway obstruction; and successful intubation. RESULTS: Two cases were decannulated completely. All cases were successfully intubated and a tracheostomy was avoided in all cases in which emergency intubation was required and the patient was bleeding. We conclude that fibre-optic bronchoscopic intubation is a viable option in head and neck oncological emergencies due to upper airway obstruction and tumour bleeding. Clinical and endoscopic judgement and operator experience are the key factors determining success.

Continuous morphine infusions for cancer pain in resource-scarce environments: comparison of the subcutaneous and intravenous routes of administration.

Acute onset of severe pain in cancer patients may be due to multiple causes. Irrespective of the etiology, adequate analgesia has to be provided as quickly as possible. The standard practices of relieving pain by using syringe pumps (syringe drivers) or infusion pumps may not be feasible in resource-scarce developing nations where many cancer patients first present at advanced stages of disease for management. This study compared the efficacy of the subcutaneous and intravenous routes of morphine administration continuously using a simple and economic technique for cancer pain management. Both routes were found to be equally effective in producing good analgesia without side effects. The drip method is a cost-effective way of providing subcutaneous morphine infusion for cancer patients and is applicable for both inpatients and home care.

Cancer pain intensity measurements in outpatients: preferences and comparison of pain scales among patients, caregivers, physicians and nurses in southern India.

Pain is frequently encountered in outpatient oncology practice and its management often is inadequate. Effective analgesia often could be provided for these patients through simple practices like pain intensity monitoring, documentation and treatment accordingly. A survey was carried out among cancer patients attending outpatient pain clinic to evaluate scale preferences, comparison of different scales as well as proxy reporting by caregiver, health professionals, for pain management. The aim of the study was to determine preferences in Indian population and to compare our study subjects' preferences to those previously reported in other cultures. A total of 99 patients participated in the study. The majority preferred a visual analogue scale (VAS). The visual analogue scale and verbal descriptive scale (VDS) were found to be equally reliable pain rating tools. Proxy reports were found to equally representative of patient's pain. VAS was the preferred pain assessment tool. In the absence of VAS scale, VDS also could be used. Proxy reports could be relied upon for management of pain.