Long-term success of low-frequency subthalamic nucleus stimulation for Parkinson's disease depends on tremor severity and symptom duration

Patients with Parkinson’s disease can develop axial symptoms, including speech, gait and balance difficulties. Chronic high-frequency (>100 Hz) deep brain stimulation can contribute to these impairments while low-frequency stimulation (<100 Hz) may improve symptoms but only in some individuals. Factors predicting which patients benefit from low-frequency stimulation in the long term remain unclear. This study aims to confirm that low-frequency stimulation improves axial symptoms, and to go further to also explore which factors predict the durability of its effects. We recruited patients who developed axial motor symptoms while using high-frequency stimulation and objectively assessed the short-term impact of low-frequency stimulation on axial symptoms, other aspects of motor function and quality of life. A retrospective chart review was then conducted on a larger cohort to identify which patient characteristics were associated with not only the need to trial low-frequency stimulation, but also those which predicted its sustained use. Among 20 prospective patients, low-frequency stimulation objectively improved mean motor and axial symptom severity and quality of life in the short term. Among a retrospective cohort of 168 patients, those with less severe tremor and those in whom axial symptoms had emerged sooner after subthalamic nucleus deep brain stimulation were more likely to be switched to and remain on long-term low-frequency stimulation. These data suggest that low-frequency stimulation results in objective mean improvements in overall motor function and axial symptoms among a group of patients, while individual patient characteristics can predict sustained long-term benefits. Longer follow-up in the context of a larger, controlled, double-blinded study would be required to provide definitive evidence of the role of low-frequency deep brain stimulation.

Effect of Low versus High Frequency Subthalamic Deep Brain Stimulation on Speech Intelligibility and Verbal Fluency in Parkinson's Disease: A Double-Blind Study

BACKGROUND

Subthalamic deep brain stimulation (STN-DBS) is an established treatment for late stage Parkinson's disease (PD). Speech intelligibility (SI) and verbal fluency (VF) have been shown to deteriorate following chronic STN-DBS. It has been suggested that speech might respond favourably to low frequency stimulation (LFS).

OBJECTIVE

We examined how SI, perceptual speech characteristics, phonemic and semantic VF and processes underlying it (clustering and switching) respond to LFS of 60 and 80 Hz in comparison to high frequency stimulation (HFS) (110, 130 and 200 Hz).

METHODS

In this double-blind study, 15 STN-DBS PD patients (mean age 65, SD = 5.8, 14 right handed, three females), were assessed at five stimulation frequencies: 60 Hz, 80 Hz, 110 Hz, 130 Hz and 200 Hz. In addition to the clinical neurological assessment of speech, VF and SI were assessed.

RESULTS

SI and in particular articulation, respiration, phonation and prosody improved with LFS (all p < 0.05). Phonemic VF switching improved with LFS (p = 0.005) but this did not translate to an improved phonemic VF score. A trend for improved semantic VF was found. A negative correlation was found between perceptual characteristics of speech and duration of chronic stimulation (all p < 0.05).

CONCLUSIONS

These findings highlight the need for meticulous programming of frequency to maximise SI in chronic STN-DBS. The findings further implicate stimulation frequency in changes to specific processes underlying VF, namely phonemic switching and demonstrate the potential to address such deficits through advanced adjustment of stimulation parameters.

Resuscitation practices for infants in the NICU, PICU and CICU: results of a national survey

OBJECTIVE

Infants requiring resuscitation at birth are resuscitated using neonatal resuscitation guidelines. Sometime after birth, resuscitation practice must transition to pediatric guidelines. There is no evidence on when this transition should occur. The objective of this study was to describe infant resuscitation practices in Neonatal Intensive Care Units (NICUs), Pediatric Intensive Care Units (PICUs) and Cardiac Intensive Care Units (CICUs).

STUDY DESIGN

An electronic survey was sent to medical directors of NICUs, PICUs and CICUs in the U.S. The survey examined resuscitation practices, and preference for use of neonatal or pediatric guidelines, for different postnatal ages, clinical scenarios and etiologies of arrest.

RESULTS

A total of 152 responses were received, including 118 NICUs, 19 PICUs and 15 CICUs. The majority of NICU responders used greater than 28 days as the time to change from neonatal to pediatric guidelines. The majority of PICU and CICU transitioned to pediatric guidelines immediately after birth. Pediatric guidelines were preferred in the PICU and CICU regardless of the arrest etiology. NICU responders favored pediatric guidelines only if the arrest was cardiac.

CONCLUSIONS

Our results suggest that infants are resuscitated using neonatal guidelines in the NICU and pediatric guidelines in the PICU and CICU, even if they are the same age and have the same etiology of arrest. There is no agreement on the time to change from neonatal to pediatric guidelines. Further research comparing the outcomes of infants resuscitated in these different units could inform future guideline refinement.

Assessment of total thrombus load in symptomatic patients with venous thromboembolism

Pulmonary embolism (PE) and Deep vein thrombosis (DVT) are separate but related aspects of the same dynamic process termed as venous thrombembolism (VTE). The existing Asian literature has shown a wide variation in the prevalence of VTE, with very limited data from the Indian subcontinent. Between January 2001 and July 2004, 1,552 patients with clinically suspected lower limb DVT underwent a combined ascending radionuclide venogram and lung perfusion scan for assessment of the total thrombus burden. Of 744 patients with radionuclide venography proven DVT, 294 (40%) had a high probability lung scan. Nearly half of these patients were asymptomatic for pulmonary embolism. The high prevalence of PE in patients with DVT suggests the need for evaluation of thrombus load in the venous as well as pulmonary circulation. A combination radionuclide ascending venography with lung perfusion scan is a useful and reliable single test for this purpose.

Immediate adverse reactions to chemotherapy: Experience of a large ambulatory treatment center

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Background: In recent years there has been a proliferation of Ambulatory Chemotherapy Treatment Centers (ATC). The incidence of hypersensitivity and other immediate adverse drug reactions (IADR) in these ATC units have not been well studied. We aim to describe our experience with IADR in our ATC. Methods: Retrospective chart review was conducted for all patients in the Adverse Drug Reaction Report database (Maxsys II) for the year 2004. Data was abstracted for demographics, risk factors, clinical characteristics, and outcomes of IADR. Overall frequency of different chemotherapeutic and monoclonal agents infused was obtained for the same period through the pharmacy database. Results: In 2004, 81,580 chemotherapy infusions were given and 256 IADR (0.31%) were reported. The mean age was 55 years and 45% were males. The most common drugs used were fluorouracil (12.9%), paclitaxel (9.4%), docetaxel (6.1%), carboplatin (5.9%), and gemcitabine (5.8%). The table shows the most prevalent agents that led to IADR. Common symptoms included flushing (52.3%), dyspnea (27.3%), chest discomfort (27%), pruritus (22.7%), and hypertension (18.4%). Diphenhydramine (85.5%), hydrocortisone (37.1%), and dexamethasone (17.2%) were the most common drugs used for treatment of IADR. Common risk factors included previous allergy to medications (43.4%), previous IADR (19.5%), previous reactions to iodide (7.8%), allergies to seafood (1.6%), allergic rhinitis (1.2%), urticaria (1.2%), and asthma (0.8%). Most patients had their chemotherapy resumed and completed (87.9%) on the same day. Discussion: IADR were rare. Most cases were easily treated and chemotherapy was restarted and completed in the same day. However, they still pose a significant burden to cancer patients. Prospective studies are needed to further evaluate the identified risk factors and most common offending agents in outpatient settings. This will help develop pathways for more effective prevention and treatment of these IADR.

[Table: see text]

No significant financial relationships to disclose.

A fatigue clinic in a comprehensive cancer center: design and experiences

Cancer-related fatigue is now the most prevalent symptom of cancer, occurring in 60-90% of patients. Fatigue has been identified by cancer patients as a factor influencing functionality and quality of life. Our objectives in developing a fatigue specialty clinic at The University of Texas M. D. Anderson Cancer Center were to improve our patients' quality of life by decreasing fatigue; educate health care providers, patients, and patients' families about cancer-related fatigue; develop an appropriate clinical and diagnostic evaluation for this symptom; correlate objective measures of fatigue with its clinical evaluation; and develop innovative treatment plans for cancer-related fatigue. This article describes the general clinic design and operations and the preliminary analysis of the first 40 patients evaluated in the fatigue clinic.

Establishment of Paediatric and Neonatal Intensive Care Units at Patan Hospital, Kathmandu: Critical Determinants and Future Challenges

Introduction: Although preventive medicine and primary care are priorities in developing countries, they must be supported by appropriate care of sick and extremely sick children in the medical facilities. Lack of resources and absence of skilled physicians and nurses may lead to poor outcomes in critically ill patients. Intensive care of newborns and children is thought to be very expensive with a low cost-benefit ratio. This presentation discusses the critical factors that facilitated the establishment of PICU and NICU in an urban public hospital in Nepal, where a good standard of Level 2 care was already provided. Aims and objectives: A cooperative model of creation and transfer of technology from the West to a resource-poor country was envisaged. PICU and NICU with six beds each were established. Design and setting: The Nick Simons Foundation, USA provided financial support for design, building and furnishing of a new Mother and Child Wing at Patan Hospital. A generous grant of $300,000 again by the Nick Simons Foundation helped equip the units. Donated equipments also included procedures, medication and storage carts. Methodology: A total of 22 volunteers, 21 from USA and one from Netherlands, were recruited to complete the three months of training. An extensive curriculum was prepared. The trainer team had monthly teleconferences and regular communications with the Chief of Paediatric Services and Nursing Director of Patan Hospital via e-mails and telephone. Responsibilities of volunteers and the host hospital were identified. Results: After 3 years of preparation, the project started in June 2009. All day lectures on topics in critical care, mock case scenarios, practical equipment training and simulated procedures led to the graduation of 60 nurses. Twenty five physicians were trained for three months. The expert team worked with the locals in preparing the units, arranging furniture and equipment, stocking carts, making inventory and preparing protocols. A protocol handbook was developed on topics such as mechanical ventilation, sedation, admission/discharge criteria, procedures and management of different disease states. Various charts such as nurse observation charts, notes by residents, procedure hand offs at change of shifts were designed and printed. Infection control practices and methods of sterilizing non disposable articles were identified and protocols written. At the end of three months the units were functioning with trained local manpower and reasonable modern equipment. Conclusion: Developing nations may not have enough resources to establish much needed critical care facilities. Developed countries can help by funding basic infrastructure and providing expertise in order to transfer knowledge and technology. Involvement in planning from the beginning and training at the host site is a preferred model of transfer of technology. Key words: Paediatric Intensive Care Unit (PICU); Neonatal Intensive Care Unit (NICU); Patan Hospital DOI: 10.3126/jnps.v31i1.4161J Nep Paedtr Soc 2010;31(1):49-56