DBS pode tornar mais lento o declínio cognitivo na doença de Alzheimer

July 22, 2016 - A multicenter phase 2 study showed that some patients with mild Alzheimer's disease (AD) who received deep brain stimulation of the fornix (DBS-f) experienced an increase in cerebral glucose metabolism, and some patients experienced a slowing of cognitive decline.

These positive effects were seen only in patients aged 65 years and older, not in younger patients.

Nevertheless, the findings are encouraging, said lead researcher Andres Lozano, MD, PhD, professor and chairman, Department of Neurosurgery, University of Toronto, Canada.

"These findings indicate that we are headed in the right direction with our research on DBS as a treatment of Alzheimer's disease. In AD, certain areas of the brain shut down and no longer metabolize glucose to the normal level, and we hope that by stimulating the circuits in the brain that are involved, that we can restore function within the fornix and that that in turn will lead to improvement in the signs and symptoms of Alzheimer's," Dr Lozano told Medscape Medical News.

The study was published online July 18 in the Journal of Alzheimer's Disease.

Age a Predictor of Response?

Dr Lozano and his group conducted an earlier phase 1 studyinvolving six patients with Alzheimer's disease. In that study, in some patients who received constant DBS to the fornix, which is a major fiber bundle in the brain's memory circuit, there was an increase in hippocampal volume after 1 year.

The current phase 2 study included 42 patients aged 45 to 85 years. Twelve patients were younger than 65 years; 30 were 65 years of age or older.

The patients had mild dementia with global Clinical Dementia Rating (CDR) scale scores of 0.5 or 1 and Alzheimer's Disease Assessment Scale–11 (ADAS-Cog 11) scores of 12 to 24 at baseline.

All patients were taking stable doses of donepezil (Aricept, Eisai Inc), galantamine (Razadyne, Janssen Pharmaceuticals, Inc), or rivastigmine (Exelon, Novartis Pharmaceutical Corporation) for at least 2 months prior to the start of the study.

The patients were implanted with DBS electrodes directed at the fornix. They were then were randomly assigned to receive either active or sham stimulation and were monitored for 12 months. Once follow-up was complete, the electrodes were turned on for all patients.

In addition to evaluating the safety of DBS-f, the investigators measured changes in cognitive function using the Alzheimer's Disease Assessment Scale–Cognitive Subscale (ADAS-Cog) and the Clinical Dementia Rating–Sum of Boxes (CDR-SB) scales at 6 and 12 months.

Secondary clinical outcomes at 6 and 12 months included the California Verbal Learning Test, Second Edition (CVLT-II), the Alzheimer's Disease Cooperative Study Activities of Daily Living scale (ACDS-ADL), and the Neuropsychiatric Inventory (NPI).

Changes in cerebral glucose metabolism were assessed with [18F]-2-deoxy-2-fluoro-D-glucose positron emission tomography (FDG-PET).

Overall, at 12 months, there was no significant difference between the patients who were receiving stimulation and those who were not. For both groups, changes in scores on the ADAS-Cog 13 and the CDR-SB were similar; both showed comparable declines. (segue...) Fonte: MedScape.

Diretrizes para referência de neurologistas: Estimulação Cerebral Profunda para a doença de Parkinson

Guidelines for Referring Neurologists: Deep Brain Stimulation for Parkinson's Disease

Who is a good candidate for deep brain stimulation for Parkinson's Disease? Guidelines for referring neurologists: 
The criteria that we use for offering patients DBS surgery for Parkinson's disease are as follows:
1.      Clear diagnosis of idiopathic PD. Patients with atypical parkinsonism or "parkinson's plus" syndromes do not respond to DBS. If there are features in the history and physical that are suggestive of atypical parkinsonism (such as very rapid progression of symptoms, autonomic failure or postural instability as early features of the disease, signs of cerebellar or pyramidal dysfunction) or an MRI suggesting an atypical syndrome, surgery is contraindicated.

2.      Intact cognitive function. A good screening test is the mini-mental status test. A score of >26 is ideal, < 24 an absolute contraindication. Patients with cognitive dysfunction have difficulty tolerating awake surgery, may have permanent worsening of cognitive function postoperatively, deal poorly with the intrinsic complexity of DBS therapy, and realize little overall functional gain even if motor performance is improved. In borderline cases, we obtain formal neuropsychological evaluation.

3.     Clear evidence of motor improvement with sinemet, with good motor function in the best on-medication state. A good screening test is the Unified Parkinson's Disease Rating Scale (UPDRS) part III, performed in 12 hours off of medication and repeated following a supratherapeutic sinemet dose. We require at least a 30% improvement in this score with sinemet. The patient should be ambulatory in the best on state without much assistance. In general surgery makes the "off" states more like the "on" states but rarely does better than the best "on" state, so a patient with poor function in best "on" (for example, nonambulatory in best "on") is a poor surgical candidate. Patients who fluctuate between good motor function while "on" and poor motor function while "off" are usually good surgical candidates. 

4.     Lack of comorbidity. Serious cardiac disease, uncontrolled hypertension, or any major other chronic systemic illness increases the risk and decreases the benefit of surgery. 

5.     Realistic expectations. People who expect a sudden miracle are disappointed with the results, and become frustrated with the complexity of the therapy.

6.     Patient age. The benefits of DBS for PD decline with advancing age, and the risks go up. Patients over 75 are informed that their benefits are likely to be modest. We have rarely implanted PD patients who are over 80.

7.     Screening MRI of the brain should be free of severe vascular disease, atrophy that is out of proportion to age, or signs of atypical parkinsonism.

8.     Degree of disability. DBS is a poor procedure to rescue someone with end stage PD, although these are the most desperate patients. It is also not appropriate for early PD when the symptoms are very well controlled on medical therapy. Patients should have an off-medication UPDRS-III score of > 25. The best time to intervene surgically is when the patient is just beginning to lose the ability to perform activities meaningful to him/her, in spite of optimal medical therapy. Often, this is associated with the development of significant motor fluctuations, dyskinesias, or both. In a patient who is still working, the time to intervene is before the patient is forced to retire on disability. 

9.     Ability to remain calm and cooperative during awake neurosurgerylasting about 2-3 hours per side of brain. A helpful "screening test" for this is how well the patient tolerates an MRI scan. For patients who are otherwise excellent candidates but could not tolerate being awake for part of the surgery, it is possible to have the DBS implantation under general anesthesia in our interventional MRI suite. 


10.  Willingness and ability to be seen for follow-up visits. Programming the DBS to find the optimal stimulation settings is very much a trial-and-error process, and the patient will need to be seen approximately once a month for at least the first few months after surgery.

Fonte: Neurosurgery.