Biomedical subjects

Bertil F M Blok

Publications and source records attributed to Bertil F M Blok.

4 recordsLinked to original sources

PubMed2006

Different brain effects during chronic and acute sacral neuromodulation in urge incontinent patients with implanted neurostimulators.

OBJECTIVE: To compare changes in regional cerebral blood flow (rCBF), using positron emission tomography (PET), during chronic and acute sacral neuromodulation (SN). SN is an effective long-term treatment for chronic urge incontinence due to urinary bladder hyperactivity, as sensory nerves, spinal and supraspinal structures are probably responsible for the action of SN. It is not known which brain areas are involved, and the optimum benefit of SN is not immediate, suggesting that induced plasticity of the brain is necessary. PATIENTS AND METHODS: Brain activity was measured in two groups: 12 urge incontinent patients (11 women and one man; mean age 52 years) in whom an implanted unilateral S3 nerve neurostimulator had been effective for >6 months (mean time after implantation 4.5 years); and eight urge incontinent patients (seven women and one man; mean age 49 years) in whom the neurostimulator was activated for the first time in the PET scanner. RESULTS: During SN in chronically implanted patients, there were significant decreases in rCBF in the middle part of the cingulate gyrus, the ventromedial orbitofrontal cortex, midbrain and adjacent midline thalamus, and rCBF increases in the dorsolateral prefrontal cortex. During acute SN in newly implanted patients, there were significant decreases in rCBF the medial cerebellum, and increases in the right postcentral gyrus cortex, the right insular cortex and the ventromedial orbitofrontal cortex. Group analysis between chronic and newly implanted patients showed significant differences in the associative sensory cortex, premotor cortex and the cerebellum, all three involved in learning behaviour. CONCLUSIONS: These findings suggests that chronic SN influences, presumably via the spinal cord, brain areas previously implicated in detrusor hyperactivity, awareness of bladder filling, the urge to void and the timing of micturition. Furthermore, SN affects areas involved in alertness and awareness. Acute SN modulates predominantly areas involved in sensorimotor learning, which might become less active during the course of chronic SN.

Acute Disease↗

PubMed2006

Urological surveillance and management of patients with neurogenic bladder: Results of a survey among practicing urologists in Canada.

OBJECTIVE: To determine current trends in management and surveillance of the neurogenic bladder population by Canadian urologists who routinely work with and provide care for these patients. METHODS: A questionnaire was mailed to members of the Canadian Urological Association. The assessment and follow-up of upper and lower urinary tract function in neurogenic bladder patients, their optimal frequency and management of related infections were the topics of inquiry. RESULTS: One hundred and five of 602 urologists responded, for a response rate of 18%. Twenty-three (22%) of the respondents did not treat neurogenic bladder patients. Four out of five urologists who treated these patients favored a yearly renal ultrasound for routine surveillance of the upper urinary tract and routinely performed urodynamic studies for evaluation of the lower tract. Only a relatively small percentage used videourodynamics. Clean intermittent catheterization (CIC) was preferred for the management of neurogenic bladder in patients with emptying difficulties. Asymptomatic urinary tract infection (UTI) was preferably not treated. Symptomatic UTI was treated with antibiotics for 7 to 10 days by about 75% of the responding urologists, while 23% of female patients and 9% of male patients were treated for less than 7 days. Although most of the urologists had access to established treatment modalities, like CIC education and bladder augmentation, only 30% made use of botulinum toxin injections. CONCLUSIONS: This study confirms that most urologists in Canada, working with neurogenic bladder patients, follow principles reported in the literature regarding the need for evaluation, surveillance, and management of the urinary tract. However, there is no consensus on the specific methods used for surveillance of the urinary system. The results emphasize the need for clear guidelines in this field of urology in Canada.

Adult↗

PubMed2002

Central pathways controlling micturition and urinary continence.

The central control of micturition and urinary continence in cats and humans is organized in a similar manner. In cats, 4 areas in the brainstem and diencephalon are implicated in the control of micturition: (1) the pontine micturition center or Barrington area directly excites bladder motoneurons in the sacral cord during micturition; at the same time, it inhibits indirectly, via inhibitory gamma-aminobutyric acidergic and glycinergic interneurons in the medial sacral cord, the external urethral sphincter motoneurons; (2) the pontine continence center activates the external urethral sphincter motoneurons during continence; (3) the midbrain periaqueductal gray receives bladder filling information; and (4) the hypothalamus, in the beginning of micturition. According to positron emission tomography studies, in humans, the same supraspinal regions are active during micturition. Furthermore, the human cingulate and prefrontal cortices are activated during both micturition and continence, indicating that these areas are important for the onset of micturition, but not for the reflex itself. The primary motor cortex of the pelvic floor is important for voluntary pelvic floor contraction, but it is not involved in normal urinary continence.

Animals↗

PubMed2002

Brain control of the lower urinary tract.

The knowledge on neural pathways involved in micturition and continence has been expanded greatly the last ten years. The aim of the present review is to summarize results obtained from animal and human experiments and to discuss the pathophysiology of relevant urological dysfunction. Four specific parts of the mammalian neural system are important for the control of micturition and continence: 1) ganglion cells in the bladder wall and sympathetic chain (autonomic) and dorsal root chain (sensory); 2) motoneurons and sensory interneurons in the caudal spinal cord; 3) the caudal brainstem; and 4) the cortical and subcortical areas. The parts 1) to 3) comprise the basic components of the micturition reflex and are interconnected via peripheral nerves and central fiber tracts. Normally, we are continent for urine continuously, except for the necessary emptying of the bladder five to eight times a day. Specific lesions of the neural pathways can result in distinct types of urological dysfunction: hypoactivity or hyperactivity of the micturition or continence pathways, and a loss of control of the beginning of micturition.

Animals↗