Vitamin A deficiency in Crohn''s disease

Fifty two patients with Crohn's disease (31 outpatients and 21 inpatients) were investigated for evidence of vitamin A deficiency. Eleven (21%) had low plasma retinol concentrations (less than 1.2 mumol/l (34.3 micrograms %)). Five of these were outpatients and plasma retinol was only slightly reduced (greater than 1.0 mumol/l (28.6%)). All outpatients weighed 80% or more of ideal, and were considered at low risk of developing vitamin A deficiency. In contrast, of the six inpatients with low plasma retinol concentration, five had a level of less than 1.0 mumol/l (28.6 micrograms %) and weighed less than 80% ideal. Three of these had impaired dark adaptation and a plasma retinol concentration of less than 0.8 mumol/l (less than 22.9 micrograms %). As a group, the inpatients were more protein depleted than the outpatients, with respect to serum albumin (p less than 0.01), transferrin (p less than 0.001), and prealbumin (p less than 0.001) but retinol binding protein levels were not significantly lower. It is suggested that patients with extensive small bowel Crohn's disease, who weigh less than 80% of ideal weight, merit measurement of plasma retinol concentration. Those with plasma retinol less than 0.8 mumol/l (less than 22.9 micrograms %) run a high risk of night blindness. Vitamin supplements should be given and protein depletion corrected.     

Improvement in a quantitative measure of bradykinesia after microelectrode recording in patients with Parkinson's disease during deep brain stimulation surgery.

It is widely accepted that patients with Parkinson's disease experience immediate but temporary improvement in motor signs after surgical implantation of subthalamic nucleus (STN) deep brain stimulating electrodes before the electrodes are activated, although this has never been formally studied. Based on anecdotal observations that limb mobility improved just after microelectrode recording (MER) during deep brain stimulation (DBS) procedures, we designed a prospective study to measure upper extremity bradykinesia using a quantitative measure of angular velocity. Measurements were made pre- and post-MER and during intraoperative DBS. Analysis of 98 STN DBS procedures performed on 61 patients showed that MER did not create adverse clinical symptoms despite concerns that MER increases morbidity. Quantitative upper extremity bradykinesia improved after MER alone, and further improvement was seen during intraoperative DBS. Electrophysiological data from each case were then compared to the improvement in bradykinesia post-MER alone and a significant correlation was found between the improvement in arm bradykinesia, the number of passes through the STN with somatosensory driving, and also with the number of arm cells with somatosensory driving in the STN, but not with total number of passes, total number of passes through the STN, or total number of cells with somatosensory driving in the STN. This study demonstrates that there is a significant improvement in upper extremity bradykinesia just after MER, before inserting or activating the DBS electrode in patients with Parkinson's disease who undergo STN DBS.     

Intra-operative STN DBS attenuates the prominent beta rhythm in the STN in Parkinson's disease

Power spectra from local field potentials (LFPs) recorded post-operatively from the deep brain stimulation (DBS) macroelectrode show prominence of the beta rhythm (11-30 Hz) in untreated Parkinson's disease (PD). Dopaminergic medication and movement attenuate this beta band in PD. In this pilot study of six sides in four patients, we recorded LFPs from the DBS electrode in untreated PD patients in the operating room. In all cases, there was a peak in the time-frequency spectrogram in the beta frequency range when the patients were at rest, which was associated with attenuation in the same range with movement. The actual frequency range and the strength of the beta peak varied among cases. In two patients, intra-operative constraints permitted recording of LFPs at rest, before and immediately after subthalamic nucleus (STN) DBS. In both patients we documented that STN DBS caused a significant attenuation in power in the beta band at rest that persisted for 15-25 s after DBS had been turned off (P < 0.01). From one case, our data suggest that the beta rhythm attenuation was most prominent within the STN itself. This study shows for the first time that STN DBS attenuates the power in the prominent beta band recorded in the STN of patients with PD. These pilot findings raise the interesting possibility of using this biomarker for closed loop DBS or neuromodulation.