The effect of weight loss on OSA severity and position dependence in the bariatric population.

BACKGROUND: The aims of this study were to determine the prevalence of positional obstructive sleep apnea (POSA) in patients undergoing bariatric surgery and to evaluate the effect of weight loss brought about by bariatric surgery on POSA. Furthermore, the authors investigated whether body mass index (BMI), neck circumference, apnea-hypopnea index (AHI), and age are predictors for POSA. METHOD: A retrospective cohort study was conducted with data collected from patients who were screened for OSA pre-bariatric surgery and completed a follow-up polysomnography post bariatric surgery from August 2008 to November 2012. Descriptive statistics were used to characterize the prevalence of POSA patients, and the Mann-Whitney and Wilcoxon signed-rank tests were used to examine differences between the POSA and non-POSA groups. A logistic regression model was used to determine predictors for POSA. RESULTS: Thirty-four percent of patients had POSA, which is significantly lower (p<0.001) than in the general population. BMI, neck circumference, and AHI were significantly lower in POSA patients. AHI was the only significant independent predictor for POSA. Of the 91 patients analyzed following bariatric surgery, 35.2% (n=32) no longer had OSA. CONCLUSION: The prevalence of POSA in patients undergoing bariatric surgery is significantly lower than the prevalence noted in the general population. A low AHI was shown to be the only significant independent predictor for the presence of POSA.

The auditory oddball paradigm in patients with vascular cognitive impairment: a prolonged latency of the N2 complex.

OBJECTIVE: The event-related potential (ERP) evoked by the auditory oddball paradigm has been investigated mainly in patients with Alzheimer's disease and in patients with different causes of subcortical dementia. Subcortical ischemic vascular disease (SIVD) seems to be an important cause of vascular cognitive impairment (VCI) frequently not fulfilling the criteria for dementia. Recognition of VCI is needed in order to provide adequate care and therapy. The aim of this study was to investigate the diagnostic value of the different elements of this response (N(1), N(2) complex and P(3) latencies) in a group of elderly patients with VCI caused by SIVD. METHODS: The study population consisted of patients with a clinical and neuropsychological diagnosis of VCI caused by SIVD (n = 38) and healthy control subjects (n = 53) aged 60 years or older. The mean Mini Mental State Examination score of both groups was 27.6, and the mean HIV Dementia Scale score was 6.1 in the patient group and 12.3 in the control group. In all subjects, the ERP was recorded under standardized conditions, and the latencies and amplitudes of N(1), N(2) and P(3) were analyzed by two clinical neurophysiologists in consensus. Both were blinded to the diagnosis. RESULTS: The N(2) latency was significantly longer in patients with VCI than in age-matched controls, whereas the latencies of the P(3) and N(1) were not significantly different. The peak-to-peak amplitude of the N(2) complex to the P(3) wave was significantly lower in the patient group. White matter abnormalities on MRI were not significantly correlated with the N(2) latency. CONCLUSION: Our findings suggest that the latency of the N(2) complex is prolonged and the peak-to-peak amplitude of the N(2) complex to the P(3) wave is lowered in patients with VCI caused by SIVD.

Identification of patients at risk for ischaemic cerebral complications after carotid endarterectomy with TCD monitoring.

OBJECTIVES: Transcranial Doppler (TCD) monitoring for micro embolic signals (MES), directly after carotid endarterectomy (CEA) may identify patients at risk of developing ischaemic complications. In this retrospective multicentre study, this hypothesis was investigated. METHODS: Centres that monitored for MES after CEA were identified by searching Medline. Individual patient data were obtained from centres willing to collaborate. The number of emboli in 1h was computed. Uni- and multivariate logistic regression analyses were performed for the variables gender, age and number of MES. Discriminative ability of MES monitoring was investigated in a ROC curve. RESULTS: Nine hundred and ninety-one patients were monitored in the first 3h after CEA. Two percent developed ischaemic cerebral complications. Univariate analysis revealed statistically significant associations between ischaemic cerebral complications and both gender and MES, but not age. In a multivariate analysis, > or =8 MES/h showed a statistically significant relationship with cerebral complications (OR 8.1, 95% CI 1.8-36), in contrast to gender (OR 2.2, 95% CI 0.9-5.5). The ROC curve yielded an AUC of 0.83 for monitoring of MES. CONCLUSIONS: These results support the use of TCD monitoring for MES shortly after CEA in order to identify patients at risk of developing ischaemic cerebral complications.

Emboli rate during and early after carotid endarterectomy after a single preoperative dose of 120 mg acetylsalicylic acid--a prospective double-blind placebo controlled randomised trial.

PURPOSE: To investigate whether a single pre-operative dose of 120 mg acetylsalicylic acid (ASA) decreased either (1) emboli rate, as detected by transcranial Doppler (TCD), during and early after carotid endarterectomy (CEA) and (2) clinical intra- and post-operative signs suggestive of embolism or increased bleeding tendency. DESIGN: Prospective, double-blind placebo controlled trial. PATIENTS AND METHODS: One-hundred consecutive patients were randomised to receive either 120 mg ASA (n = 48) or placebo (n = 49) by suppository on the night before CEA; three patients were excluded. Emboli were counted and expressed as emboli rate (ER). The incidence of bleeding complications was assessed. Surgeons were asked to indicate which patients had received ASA or placebo. RESULTS: There were no significant differences between the ASA and placebo groups in ER in the intraoperative and postoperative periods. ER higher than 0.9 min(-1) was associated with a significantly increased risk of complications (26 vs. 0%, P < 0.01). No extra bleeding complications were observed in the ASA group. Surgeon assessment of whether or not ASA had been administered had a sensitivity of 42% and a specificity of 70%. CONCLUSION: A single pre-operative dose of ASA (120 mg) did not reduce significantly the emboli rate during and after CEA and surgeons could not correctly identify whether or not ASA had been administered.

Is cardiovascular disease a risk factor in the development of axonal polyneuropathy?

OBJECTIVES: To determine if cardiovascular disease may be a risk factor in the development of chronic idiopathic axonal polyneuropathy (CIAP). METHODS: In this incidence case-control study, the prevalence of cardiovascular disease and risk factors in 97 patients with CIAP (mean age 67.5 (SD 7.9) years) and the prevalence of neuropathic features in 97 patients with peripheral arterial disease (PAD) (mean age 67.1 (SD 7.3) years) were investigated. The results were compared with those for 96 age and sex matched controls without diagnosed PAD or polyneuropathy (mean age 67.5 (SD 9.1) years). In a randomly chosen subgroup of 23 patients with CIAP, 42 patients with PAD, and 48 controls, an electrodiagnostic investigation was performed. RESULTS: Patients with CIAP more often had manifest cardiovascular disease and cardiovascular risk factors than controls (stroke 18% v 6% of patients, odds ratio (OR) 3.2 (95% confidence interval (CI) 1.8 to 5.9); heart disease 29% v 15%, OR 2.4 (95% CI 1.2 to 4.9); family history of cardiovascular disease 42% v 21%, OR 2.8 (95% CI (1.5 to 5.2); hypertension 56% v 39%, OR 2.0 (95% CI 1.1 to 3.6); hypercholesterolaemia 46% v 21%, OR 3.3 (95% CI 1.5 to 7.3); current smoking 38% v 23%, OR 2.1 (95% CI 1.1 to 3.9)). The prevalence of cardiovascular disease and cardiovascular risk factors was lower than in patients with PAD. Patients with PAD more often had polyneuropathy than controls (15% v 5%, OR 3.3 (95% CI 1.1 to 10.0)). There was a trend towards lower nerve conduction velocities and lower amplitudes on electrodiagnostic investigation compared with controls. CONCLUSION: This study shows that cardiovascular disease and CIAP often coexist, and therefore cardiovascular disease may be a cofactor in the development of CIAP.

EEG evidence for shunt requirement during carotid endarterectomy: optimal EEG derivations with respect to frequency bands and anesthetic regimen.

Currently there is no consensus on the derivations that should be used for EEG monitoring during carotid endarterectomy (CEA). The aim of this study was to determine which derivations distinguish the best between patients requiring a shunt and patients who do not need a shunt. Four predefined frequency bands and two regimens for general anesthesia (isoflurane versus propofol) were used. EEG data (16 channels) were obtained from 152 EEGs recorded during carotid endarterectomy. Analog EEG signals of preclamp and clamp periods of 100 seconds were digitized to compute power spectra. Changes in power during clamping were calculated for all possible derivations in four predefined frequency bands and were expressed as Z-scores. For each derivation, the area under the receiver operating characteristics curve was calculated. Derivations with the greatest area under the receiver operating characteristics curve were considered to distinguish the best between the shunt and the nonshunt groups formed in retrospect on the basis of consensus between three independent and experienced board-certified electroencephalographers. The two different anesthetic regimens resulted in different patterns of EEG changes because of clamping. The optimal derivations to differentiate between the shunt and the nonshunt groups also differed for the two anesthetic regimens, although for both conditions, anterior head regions were especially preferred. The optimal derivations are given for each anesthetic regimen.

Neuromuscular findings in thyroid dysfunction: a prospective clinical and electrodiagnostic study.

OBJECTIVES: To evaluate neuromuscular signs and symptoms in patients with newly diagnosed hypothyroidism and hyperthyroidism. METHODS: A prospective cohort study was performed in adult patients with newly diagnosed thyroid dysfunction. Patients were evaluated clinically with hand held dynamometry and with electrodiagnosis. The clinical features of weakness and sensory signs and the biochemical data were evaluated during treatment. RESULTS: In hypothyroid patients 79% had neuromuscular complaints, 38% had clinical weakness (manual muscle strength testing) in one or more muscle groups, 42% had signs of sensorimotor axonal neuropathy, and 29% had carpal tunnel syndrome. Serum creatine kinase did not correlate with weakness. After 1 year of treatment 13% of the patients still had weakness. In hyperthyroid patients 67% had neuromuscular symptoms, 62% had clinical weakness in at least one muscle group that correlated with FT4 concentrations, but not with serum CK. Nineteen per cent of the patients had sensory-motor axonal neuropathy and 0% had carpal tunnel syndrome. The neuromuscular signs developed rapidly, early in the course of the disorder and were severe, but resolved rapidly and completely during treatment (average time 3.6 months). CONCLUSIONS: Neuromuscular symptoms and signs were present in most patients. About 40% of the hypothyroid patients and 20% of the hyperthyroid patients had predominantly sensory signs of a sensorimotor axonal neuropathy early in the course of thyroid disease. Weakness in hyperthyroidism evolved rapidly at an early stage of the disorder and resolved completely during treatment, suggesting a functional muscle disorder. Hand held dynamometry is sensitive for the detection of weakness and for the clinical evaluation of treatment effects. Weakness in hypothyroidism is more difficult to treat, suggesting myopathy.

Distal neuralgic amyotrophy.

Neuralgic amyotrophy consists of severe pain around the shoulder and arm followed by weakness in one or several muscles of the same area. We describe four patients with distal neuralgic amyotrophy in whom acute, severe, and transient pain around the shoulder or arm was followed by weakness of the forearm and hand muscles only. Minor sensory symptoms were present in only one patient. The presence of structural lesions causing the extent of the forearm and hand motor deficit was excluded by ancillary examinations. Electrophysiological studies showed a motor axonopathy and minimal sensory axonopathy. A follow-up of 2 years or longer showed either spontaneous improvement or residual motor deficit. Unfamiliarity with a clinically distal localization of neuralgic amyotrophy may result in misdiagnosis of lower cervical (poly)radiculopathy in view of the distal localization of the motor deficit and the high prevalence of coincidental abnormalities of the lower cervical spine on plain radiography, computed tomography, or magnetic resonance imaging.

Influence of caffeine and caffeine withdrawal on headache and cerebral blood flow velocities.

Caffeine consumption may cause headache, particularly migraine. Its withdrawal also produces headaches and may be related to weekend migraine attacks. Transcranial Doppler sonography (TCD) has shown changes in cerebral blood flow velocities (BFV) during and between attacks of migraine. In order to examine whether headache and changes in BFV could develop from controlled caffeine alterations, 20 healthy volunteers without a headache history, underwent clinical evaluation, TCD and serum caffeine measurements on four occasions, comparing conditions of regular caffeine intake, caffeine withdrawal and "re-caffeination". After 24 h of complete caffeine abstinence, 10 suffered from moderate to severe headaches with complete recovery within 1 h after caffeine intake. The BFVs in both middle cerebral, both posterior cerebral and basilar arteries were higher following the withdrawal period, reaching statistical significance in the left middle cerebral basilar and both posterior cerebral arteries. BFVs decreased significantly within half an hour after caffeine intake in all subjects, and were similar to baseline values after 2 h. Our results emphasize the relationship between caffeine withdrawal, the development of headache and alterations in cerebral blood flow velocities. Also, these findings indicate that accurate interpretation of TCD measurements should account for the influence of caffeine on BFVs.

Normal values of patellar and ankle tendon reflex latencies.

The clinical value of latency measurement of tendon reflexes in neurological patients has been reported by several authors. However, normal values are not readily comparable. In the present study, latencies and amplitudes of patellar (PTR) and ankle tendon reflexes (ATR) were measured at rest and after facilitation in 102 normal controls. A manually operated reflex hammer, tipped with electrically conductive rubber, ensured an immediate start of the sweep of the oscilloscope. Latencies showed a significant correlation with height (r = 0.70 for PTR and r = 0.72 for ATR, P < 0.0001) and to a lesser degree with age (r = 0.16 and r = 0.30, P < 0.0001). While amplitudes were highly variable, rendering them less useful for diagnostic purposes, latencies showed minimal intra-individual variability (CV 1.5 and 0.8%, respectively). Correlation of ATR-latency with the H-reflex latency of the soleus muscle was very high (r = 0.97, P < 0.0001). Comparison with three other hammer types yielded corresponding results with a hammer supplied with a piezo-electric element; however, significantly shorter latencies were found with a hammer with a microswitch, and with another hammer with a spring-contact, due to a delay from the tap on the tendon until the start of the sweep of the monitor.

EMG before and after cervical anterior discectomy.

INTRODUCTION: In patients with cervical root syndromes, the relation between clinical findings and EMG results, the value of the registration of the H-reflex latency of the flexor carpi radial muscle (HFCR) and the rate of recovery of EMG abnormalities following surgery are unclear. METHODS: In 68 patients with cervical radicular syndromes caused by intervertebral disc lesions, EMG was made shortly before anterior cervical discectomy and four months later. EMG consisted of needle myography and bilateral determination of the HFCR. RESULTS: Results of HFCR were unrelated to findings on needle myography. Preoperative EMG abnormalities were related to more severe clinical and myelographic findings. A preoperative abnormal HFCR correlated with good clinical outcome. No relation was found between the clinical outcome and EMG-findings during follow-up. CONCLUSION: Determination of HFCR is a useful EMG-test, but further comparison to tendon reflexes is necessary. EMG identifies patients with more severe root lesions, but cannot be used for evaluation of persistent complaints within the first half year following surgery.

Somatosensory evoked potentials after iohexol myelography.

Tibial nerve and S1 dermatome somatosensory evoked potentials (SSEPs) were recorded before and after iohexol lumbar myelography in order to evaluate possible neurotoxic effects of this contrast medium. No significant change in SSEP latencies nor amplitudes was noted after iohexol myelography, supporting the low neurotoxic profile of this contrast agent. Results were compared to those of a control group of patients before and after lumbar puncture (LP), without injection of contrast agent. In this group also no significant change in SSEP components was found, indicating that a preceding LP does not affect this electrophysiological examination.

A rare cause of lumbosacral plexus neuropathy.

This is the second report of a case in which a uterine myoma, one of the most common benign tumours of women, was the cause of a lumbosacral plexus neuropathy. The possibility of uterine myoma should be considered in the differential diagnosis of neuropathy of the lumbosacral plexus in women.

Thyroid crisis presenting as coma.

Coma is a rare complication of thyrotoxicosis. A patient with coma due to a thyroid crisis is reported. The EEG showed extremely slow and low voltage activity, which gradually returned to normal. Coma as a presenting symptom of thyroid crisis has not been reported before.