Referred Sensation Areas in a Bilateral Toes Amputee

Various mechanisms in generating phantom limb pain (PLP) have been hypothesized in the literature. However, there still is no clear understanding of how PLP develops and why it presents. Amputation leads to permanent anatomical and physiological changes of the neural path previously supplying the brain with sensory input, as well as to formation of referred sensation areas (RSAs) on the stump or its vicinity. Sensations may be evoked in the lost body part upon stimulation of RSAs that may be exploited as artificial sensory input. In this work, we present the analysis of RSA maps from a 45-year-old female with bilateral toes amputation. Maps of the RSAs were identified in eight sessions over 107 days, characterized by dynamics in both location and type of associated evoked sensation. The evoked sensations were reported to be felt like current through and brushing of the phantom toes at low intensities close to the sensation threshold. Sensations evoked by electrical stimuli delivered through electrodes covering one or more RSAs approximated the sensation of summation of sensations evoked by mechanical stimuli (light brushing). No painful evoked sensations were observed

The Fascicle Undulation Effect on the Activating Function in Magnetic Stimulation of Peripheral Nerves with Transverse and Longitudinal Fields

Analysis of activating function for a long, myelinated nerve fiber with undulating path in transverse and longitudinal induced electric fields was performed. The induced electric field was computed using a finite element model composed by a round coil beneath a bath with saline solution. Longitudinal and transverse components of the induced electric field were computed along two axes, one tangential and the other axial to the coil. The influence of a transverse field on the modified activating function was analyzed when the fiber path was determined by the fascicle undulation, and by the fascicle undulation plus the fiber undulation inside the fascicle. For the first path type, undulation wavelength of 40 to 90 mm and 0.8 mm amplitude determined a classic activating function with: (a) multiple virtual cathodes that could generate two or three stimulation sites for axially oriented coil, and (b) virtual cathode with distorted shape in amplitude up to 35% and location up to 67% for tangentially oriented coil. For axially oriented coil, the transverse field term of the modified activating function was comparable in amplitude with the classic activating function, however significant attenuation could occur due to perineurium. For the second path type with wavelength of tenths of millimeters and amplitudes of a quarter of the wavelength, the classic activating function had such a dramatic increase in the spatial frequency that could not predict the stimulation site with the usual interpretation of the virtual cathode. Similarity between the results obtained with the first path type and the ones obtained in a previous in-vitro experiment suggests that the undulating fascicles within the nerve trunk can be responsible for stimulation with transverse fields

Effect of cisapride on gastric emptying in premature infants with feed intolerance

ObjectiveTo assess the effect of cisapride on gastric emptying and gastro-oesophageal reflux (GOR) symptoms in preterm infants with feed intolerance.MethodsSixteen preterm infants (gestational age 24-35 weeks) with feed intolerance were enrolled in the study. Infants were randomized to receive 7 days of cisapride 0.2 mg/kg four times a day, immediately followed by 7 days of placebo or vice versa. Gastric emptying was measured using the [13C]-octanoic acid breath test prior to study entry and repeated on day 5, 6 or 7 after randomization and 5, 6 or 7 days after crossover. The symptoms of GOR were monitored during the study period using a standardized reflux chart. Weight was recorded daily.ResultsThere was no change in gastric emptying in infants prescribed cisapride (gastric half-emptying time (t1/2) 31.9 +/- 4.7 vs 34.2 +/- 3.9 min for placebo vs cisapride, respectively; P = 0.65). Infants on cisapride had slower growth and there was no change in reflux symptoms.ConclusionsThe use of cisapride in preterm infants with feed intolerance cannot be recommended