Corpus cavernosum electromyography (CC-EMG): a new technique in the diagnostic work-up of impotence

We have studied cavernous electrical activity in 42 subjects, healthy volunteer controls and groups of impotent patients using a nonspecific electromyographic device (PICO-MENFIS) and a specific one, the SPACE-recorder 7500 designed to achieve electric recordings from the corpora cavernosa. In all of the patients, we detected under basal conditions a mean amplitude of 583 +/- 323 microV, a mean duration of 4.9 +/- 7 s, a mean polyphasicity of 3.5 +/- 1.4. It should be emphasized that a significant reduction of potential amplitudes was recorded after pharmacological stimulation in both the controls and the impotent patients. The healthy controls showed amplitudes significantly higher than the impotent patients after radical cystectomy (715 +/- 141 microV versus 381 +/- 227 microV, p < 0.01). The patients after a "nerve-sparing" radical cystectomy with a mean amplitude similar to the controls (500-700 microV) reacted well to the intracavernous drugs in a high percentage of cases. In our experience, CC-EMG seems to be a reliable method which can pinpoint directly lesions to the cavernous smooth muscle and penile autonomic nerves. It has also been able to assess the effects of stress, anxiety and pain on the erectile mechanisms.     

Repeated tetanic stimulation in piriform cortex in vitro: epileptogenesis and pharmacology

1. Focal cortical epilepsy was investigated by applying tetanic stimulation repeatedly (100 Hz. 2 s in duration, once every 10 min, 10 episodes) to layer III association fibers in rat piriform cortex slices and recording both extracellular and intracellular responses from the endopiriform nucleus. To promote excitability, piriform slices were incubated in artificial cerebrospinal fluid (ACSF) containing 0.9 mM Mg2+ and 5 mM K+, at an initial temperature of 10-12 degrees C, which was allowed to warm passively to room temperature. 2. Responses recorded extracellularly in the endopiriform nucleus consisted of two types: weak stimulation evoked an early-occurring, small-amplitude, negatively deflecting potential; strong stimulation evoked a more complex response comprising both an early potential of maximal amplitude and a later-occurring epileptiform potential of greater amplitude and longer duration. Late-occurring epileptiform potentials were not observed in slices incubated in ACSF at room temperature. 3. Both the early potential and the late-occurring epileptiform responses were abolished by the non-N-methyl-D-aspartic acid (non-NMDA) subtype of glutamate receptor blocker, 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX; 10 microM). Application of D(-)-2-amino-5-phosphonopentanoic acid (APV; 50 microM) to block NMDA receptors was without effect on the early potential but diminished the late-occurring epileptiform potential. The late-occurring potential was unable to follow stimulation delivered at a frequency of 1 Hz. These results suggest that the early potential was generated monosynaptically and dependent solely on the activation of non-NMDA receptors, whereas the late-occurring epileptiform potential was polysynaptic in origin and possessed both a CNQX- and an APV-sensitive component. 4. Responses increased progressively in both amplitude and duration after tetanic stimulation. The threshold intensity required to evoke the complex dual-component potential was reduced by tetanic stimulation. An increase in multiunit spiking activity, indicating an increase in synchronous discharges, was also observed. A residual potential could be evoked in the presence of CNQX (10 microM) after the tetanic stimulation procedure. 5. Spontaneous discharges occurred as early as after the first episode of tetanic stimulation and persisted for the duration of the experiment. Spontaneous discharges were abolished by either CNQX or by a fourfold increase in extracellular Mg2+ concentration, the latter reversibly. APV reduced the frequency of spontaneous discharges by 38.6 +/- 9.3% (mean +/- SE). The conventional anticonvulsant drug 5,5-diphenylhydantoin, the benzodiazepine receptor agonist midazolam, and the benzodiazepine receptor antagonist flumazenil were without effect on the frequency of spontaneous discharges. Evoked responses were also unaffected by either 5,5-diphenylhydantoin or midazolam. Slices not exposed to cold ACSF, although demonstrating potentiation of evoked responses after tetanization did not produce spontaneous epileptiform discharges. 6. Intracellular recordings from endopiriform neurons revealed the cellular correlates of the extracellular responses. Weak stimulation evoked a small-amplitude depolarizing potential. Increasing the intensity of stimulation increased the amplitude of this response and also evoked a second depolarizing potential of greater amplitude occurring at variable latencies. Maximal stimulation evoked an action potential. After tetanic stimuli, responses resembling a paroxysmal depolarizing shift consisting of a depolarizing potential with superimposed multiple action potentials were evoked reliably. Passive membrane properties after repeated tetanic stimulation were not different when compared with control. 7. This novel model of in vitro focal cortical epilepsy has many features characteristic of conventional kindling including 1) progressive nature; 2) reduced threshold to evoke discharges; and 3) persist     

Recording of atrial and ventricular signal averaged ECGs in patients with mitral valve prolapse syndrome

The aim of the study was to assess the time-domain parameters of atrial signal-averaged ECG (ASAECG) and ventricular signal-averaged ECG (SAECG) in patients with mitral valve prolapse (MVP) and healthy ones. Fifty patients with MVP (15 men, 35 women, mean age--37.1 +/- 8.9 years) and 50 healthy controls (36 men, 14 women, mean age 38.2 +/- 4.7 years) were studied). The following time-domain parameters of ASAECG were analysed: the root mean square voltage of the terminal 10, 20, 30 ms of filtered P wave (RMS10, 20, 30) and the total duration of filtered P wave (PWD). The atrial late potentials (ALP) were defined as the presence: RMS10 < 4 microV i PWD > 123 ms. As the time-domain parameters of SAECG we analysed: the root mean square voltage of the terminal 40, 50 ms of the filtered QRS (RMS 40, 50), the total filtered QRS duration (t-QRS) and the low-amplitude signal duration < 40 microV in the terminal QRS (LPD). The ventricular late potentials (VLP) were defined as the presence of at least two of the following criteria: t-QRS > 114 ms, RMS 40 < 20 microV i LPD > 38 ms. There was no difference in the time-domain parameters of ASAECG between patients with MVP and controls: RMS 10: 4.5 +/- 1.8 microV vs 4.8 +/- 1.9 microV, RMS 20: 6.3 +/- 2.2 microV vs 6.1 +/- 2.2 microV, RMS 30: 8.3 +/- 2.5 microV vs 7.1 +/- 2.7 microV and PWD 113 +/- 11.7 ms vs 116 +/- 15.2 ms, respectively. Three patients with MVP (6%) and 5 controls (10%) revealed ALP. THE time-domain parameters of SAECG did not differ in patients with MVP and controls: RMS 40: 40.2 +/- 29.1, microV vs 35.5 +/- 18.2 microV, RMS 50: 68.2 +/- 40.1 microV vs 64.4 +/- 33.6 microV and t-QRS-101.4 +/- 10.7 ms vs 101.8 +/- 10.9 ms i LPD--28.7 +/- 10.0 ms vs 28.3 +/- 10.0 ms, respectively. VLP were found in 7 patients with MVP (14%) and 5 controls (10%). Our findings suggest that time-domain parameters of ASAECG and SAECG could not differentiate patients with MVP and healthy ones. Moreover, the presence of ALP and VLP in MVP group did not correlate with supraventricular and ventricular arrhythmias recorded on ambulatory ECG.     

Microelectrode recordings from transected nerves in amputees with phantom limb pain

Intraneural microelectrode recordings were made from the nerve supplying the phantom area in two patients suffering from phantom limb pain. Spontaneous activity was prominent in both cutaneous and muscle fascicle of the nerves. Tapping the neuromata which accentuated the phantom limb pain, induced afferent discharges with both short and long latencies, the latter from fibres with a conduction velocity of only 0.5 m/sec. Blocking the neuromata with lidocaine completely abolished the tap-induced afferent discharges and the tap-induced accentuation of the phantom pain. The spontaneous pain was, however, unchanged, as was the spontaneous activity recorded.     

HCV/HGV coinfection and cryoglobulinemia

OBJECTIVE: To determine the rates of spontaneous pregnancies among women whose infertile male partners had sperm surface antibodies. DESIGN: Retrospective analysis. SETTING: Infertility clinic of a university referral center. PATIENT(S): One hundred fifty-seven infertile couples; the male partner had IgA and/or IgG sperm surface antibody concentrations of >10%. INTERVENTION: None. MAIN OUTCOME MEASURE(S): Spontaneous pregnancy rates (PRs) over 6 years. RESULT(S): Spontaneous PRs correlated negatively with antibody concentrations. CONCLUSION(S): Although the chance of spontaneous pregnancy among women whose partners had sperm antibody concentrations of <50% was good, intracytoplasmic sperm injection should be recommended to patients with concentrations of >90%.     

Normal median near nerve potential

In routine studies of sensory nerve conduction, only fibers > or = 7 microns in diameter are analyzed. The late components which originate from thinner fibers are not detected. This explains why a normal sensory action potential (SAP) may be recorded in patients with peripheral neuropathies and sensory loss. In the present study we investigated the late component of the median SAP with a near nerve needle electrode technique in 14 normal volunteers (7 men and 7 women), aged 34.5 +/- 14.8 years. The stimulus consisted of rectangular pulses of 0.2-ms duration at a frequency of 1 Hz with an intensity at least 6 times greater than the threshold value for the main component. Five hundred to 2000 sweep averagings were performed. The duration of analysis was 40 or 50 ms and the wave analysis frequency was 200 (-6 dB/oct) to 3000 Hz (-12 dB/oct). We used an apparatus with a two-channel amplifier system, 200 M omega or more of entry impedance and a noise level of 0.7 microVrms or less. The main component mean amplitude, conduction velocity and latency and the late component mean amplitude, conduction velocity and latency were respectively (mean +/- SD): 26.5 +/- 5.42 microV, 56.8 +/- 5.42 m/s, 3.01 +/- 0.31 ms, 0.12 +/- 0.04 microV, 16.4 +/- 2.95 m/s and 10.6 +/- 2.48 ms. More sophisticated equipment has an internal noise of 0.6 microVrms. These data demonstrate that the technique can now be employed to study thin fiber neuropathies, like in leprosy, using commercial electromyographs, even in non-academic practices.     

Median nerve somatosensory evoked potentials during isoflurane anaesthesia

PURPOSE: The effect of isoflurane on the subcortical P14 component of the median nerve somatosensory evoked potential (SEP) is poorly known. We studied whether the P14 wave from the upper brainstem, recorded with a nasopharyngeal electrode, was attenuated at the isoflurane-induced EEG burst-suppression level. We also compared the effect of isoflurane on the P14, cervical N13 and cortical N20, N35 and N6, components. METHODS: Seventeen elective patients were anaesthetized with isoflurane. Somatosensory evoked potentials were recorded prior to anaesthesia, at 0.5 MAC and 1 MAC end-tidal isoflurane as well as at the level when EEG was in burst-suppression (mean 1.9 vol% end-tidal isoflurane). RESULTS: Isoflurane had varying effects on the subcortical components of median SEP. The amplitude of nasopharyngeal P14 was stable, but the mean latency increased from 14.4 +/- 1.2 msec at 0.5 MAC to 15.2 +/- 1.1 msec at burst-suppression level (P < 0.05). In contrast, the N13 neck response amplitude was attenuated from 3.3 +/- 0.6 microV to 2.6 +/- 0.5 microV (P < 0.005) without latency changes. The latency of the cortical N20 wave was increased from 19.7 +/- 1.1 msec at awake to 24.4 +/- 1.6 msec at burst-suppression level (P < 0.0001) and amplitude was reduced from 3.3 +/- 1.1 microV to 1.3 +/- 0.6 microV (P < 0.0001). The later cortical components were attenuated even during 0.5 MAC isoflurane and were not recordable during EEG burst-suppression. CONCLUSION: We conclude that P14 can reliably be recorded with nasopharyngeal electrodes during isoflurane anaesthesia, even during EEG burst-suppression, when the N20 wave is attenuated. In contrast, the middle-latency SEP components are sensitive to isoflurane anaesthesia.     

Birthweight and neonatal outcome at the Muhimbili Medical Centre, Dar es Salaam, Tanzania

BACKGROUND: The level of residual noise in auditory brainstem responses (ABR) depends not only on the number of averages but also on the amplitude of background noise and on the frequency of artifacts. This paper describes the influence of digital filtering and of different methods of artifact suppression on the residual noise of ABRs. METHOD: Amplitude of background noise was estimated for 1033 ABRs recorded under suprathreshold stimulation (70 and 90 dB nHL) in 251 subjects. In 45 ABR recordings in 15 subjects, all 4000 individual sweeps were stored for off-line simulation. The power spectrum of background noise was investigated using an FFT analyzer. RESULTS: A great variability of mean noise amplitude was found both between subjects and in the recordings for each subject. Depending on the slope of the analogue 100-Hz high-pass filter, mean RMS values of background noise of 4.2 microV (6 dB/Oct.) and 2.5 microV (12 dB/Oct.), respectively, were found. Digital high pass filtering before averaging was found to increase the signal-to-noise ratio (SNR) considerably. CONCLUSIONS: Results indicate that (i) effective suppression of low-frequency noise components can only be achieved by zero phase digital filtering and (ii) if clipping of noise amplitude to 25 microV is used, optimized artifact rejection as weighted averaging or adopted artifact rejection levels have only small effect on the SNR.     

Activation of muscarinic receptors during blockade of GABA(A)-mediated inhibition induces synchronous epileptiform activity in immature rat hippocampus

We investigated the effects of the cholinergic agonist carbachol (25 microM) on the synaptic potentials recorded extracellularly and intracellularly from the CA3 area of immature hippocampal slices of the rat (postnatal days 10-20). In control conditions, carbachol reduced the amplitude of evoked synaptic responses (n=8) and did not induce any spontaneous synchronous activity (n=12); the depressant effect of carbachol was mimicked by acetylcholine (100 microM, in eserine 10 microM, n=5) and was reversed by the muscarinic antagonist atropine (1 microM, n=2). The GABA(A)-receptor antagonist bicuculline (10 microM) enhanced the amplitude and duration of the evoked synaptic responses and induced infrequent (0.016-0.045 Hz) spontaneous synchronous discharges in 23/37 of the slices. Application of carbachol in the presence of bicuculline reduced the amplitude of the evoked synaptic responses (n=21) and in addition induced synchronous discharges with rates of occurrence 0.075-0.225 Hz, in 64/68 slices. Both effects were mimicked by acetylcholine and eserine, and antagonized by atropine. The specific muscarinic antagonists pirenzepine (M1-type), tripitramine (M2-type), 4-diphenylacetoxy-N-methylpiperidine methiodide (M3-type) and tropicamide (M4-type) (all tested at 0.1-1 microM) reversibly reduced the frequency of synchronous carbachol-induced discharges. In addition, these discharges were reversibly blocked by high Ca2+ perfusion medium (7 mM CaCl2, n=4) and by the glutamate receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (10 microM, n=7). Synchronous epileptiform discharges were recorded from both CA1 and CA3 areas in intact slices (n=3), but only from CA3 following disruption of the CA1-CA3 synaptic connections (n=3). These experiments suggest that activation of muscarinic receptors during blockade of GABA(A)-mediated potentials, may enhance synchronous epileptiform activity in immature (postnatal days 10-20) hippocampus, through activation of local excitatory circuits and that endogenous acetylcholine may be sufficient to play this role.     

Persistence of porcine reproductive and respiratory syndrome virus in intensive farrow-to-finish pig herds

We analyzed signal-averaged electrocardiograms (ECG) obtained in 50 patients with recent myocardial infarction (RMI: 25 anterior and 25 inferior) and 20 normal subjects to determine the relationship between the initial portion of the signal-averaged QRS complex and cardiac function and infarct size. We examined (1) the root mean square voltage (RMS10-40, microV), (2) the integration (A10-40, microV.msec) at 10-msec intervals over the first 40 msec of the signal-averaged QRS complex, and (3) the intervals (T) of the magnitude of the signal-averaged ECG achieved at 10-microV intervals over the first 40 microV (T10-40, msec). The mean RMS10-40 (p < 0.01) and A10-40 (A10, p < 0.05; A20-40, p < 0.01) were significantly lower and the T10-40 (p < 0.01) was significantly longer in RMI patients than in normal subjects. The RMS10-40 (p < 0.01) and A10-40 (p < 0.05) were significantly lower and the T10-40 (T10.20, p < 0.01; T30.40, p < 0.05) was significantly longer in patients with anterior RMI patients than in patients with inferior RMI. The A30 was correlated with the ejection fraction and total creatine kinase (CK) release in all patients (r = 0.73, and -0.78, respectively, p < 0.001). These results suggest that the A30 may be an important predictor of ventricular dysfunction and infarct size in patients with RMI.     

Efficient gene transfer to human squamous cell carcinomas by the herpes simplex virus type 1 amplicon vector

We determined the diagnostic value of the EEG in young children with Angelman syndrome (AS) and Rett syndrome (RS). EEGs, recorded before 5 years of age, of 10 patients with AS, 10 with RS and 10 with mental retardation of other origin were studied blindly by two examiners for the presence of the following items: (A) 4-6 Hz rhythmic activity of over 200 microV; (B) 2-3 Hz frontal activity of 200-500 microV; (C) posterior spikes; (D) triphasic frontal waves; (E) central and/or centro-temporal spike-wave complexes; and (F) other epileptic discharges. Based on these items the EEGs were scored as AS (A-D); RS (E-F); or other. Examiners never made a mistake between AS and RS. One examiner labeled 6 of 10 AS cases correctly, the other 5; 4 (5) were characterized as 'other.' In RS cases 5 were labeled as 'other' by the first examiner and 3 by the second one. We conclude that EEG patterns of AS and RS are sufficiently different to help differentiate between AS and RS at a young age, which has a bearing on genetic counseling.     

Quantitative analysis of electromyogram interference pattern in extraocular muscle

Turns and amplitude analysis of the electromyogram (EMG) interference pattern has been applied to the extraocular muscles for the first time in the literature, to the best of our knowledge. EMGs of 261 horizontal rectus muscles recorded during the past 18 years were retrospectively examined and divided into four categories according to the clinical diagnosis: 56 complete palsy due to neuropathy, 67 incomplete palsy due to neuropathy, 19 myopathy, and 119 normal. The number of turns per second and mean amplitude between a pair of successive turns were automatically calculated by computer. Significant differences (P < 0.05) were encountered in all data among the four clinical categories except for the number of turns between myopathy and normal. The number of turns was plotted against the amplitude in each muscle on an X-Y diagram. The data of completely paretic muscle showed less number of turns and smaller amplitude and were clearly distinguishable from the data of the other three categories on the X-Y diagram. The interference pattern of incomplete palsy and myopathy had smaller amplitude than that of normal muscle. However, most of the data overlapped on the X-Y diagram particularly between data of incomplete neuropathy and myopathy.     

The effect of light history on the aspartate-isolated fast-PIII responses of the albino rat retina

PURPOSE: To assess the effect of light-rearing history on the photon-capturing ability, amplitude, and kinetics of the fast-PIII response of the retina. METHODS: Albino rats were raised on 12-hour light-12-hour dark cycles, with illumination at 3 lux or 200 lux, and killed at approximately 12 weeks. Retinal rhodopsin content was measured spectrophometrically. The morphology of the rod outer segments (ROS) and the thickness of the outer nuclear layer were determined histologically. Electroretinograms of isolated retinas to 3-microsecond flashes were recorded. The kinetics of fast PIII responses were assessed with a model of the phototransduction cascade. RESULTS: Total rhodopsin of 200 lux animals was reduced to 60% that of 3 lux animals: 2.3 +/- 0.2 versus 1.4 +/- 0.1 nmol/eye (mean +/- SD). Length of ROS of 200 lux animals was reduced to 68% of the length of that of 3 lux animals: 20.1 +/- 1.2 versus 13.7 +/- 0.5 microns. The saturated amplitude of fast PIII of 200 lux animals was reduced to 56% that of the 3 lux group: 134 +/- 27 versus 239 +/- 37 microV (T = 22 degrees C). Fast PIII responses of both groups are well described by the kinetic model before slow PIII intrusion (up to 100 ms). Estimated kinetic parameters of the transduction cascade did not differ reliably between the two groups. CONCLUSIONS: Diminished saturated amplitude of fast PIII in 200 lux animals is accounted for by the hypothesis that fast PIII is directly proportional to the rod photocurrent and by the finding that the ROS of 200 lux animals are short compared to those of 3 lux animals. Similarity in estimated kinetic parameters of phototransduction suggests that the rods of the two groups differ little in the biochemistry underlying the activation phase of phototransduction.     

Mechanisms underlying spontaneous and induced ventricular arrhythmias in patients with idiopathic dilated cardiomyopathy

BACKGROUND: To define the electrophysiological mechanism(s) of inducible and spontaneously occurring ventricular arrhythmias associated with nonischemic cardiomyopathy, 3-dimensional intraoperative mapping from 156 intramural sites was performed in 6 patients with idiopathic dilated cardiomyopathy undergoing cardiac transplantation. METHODS AND RESULTS: Electrode density was sufficient to determine the mechanism for 52 of 74 beats of nonsustained ventricular tachycardia (VT) induced by programmed stimulation and 9 of 11 beats of spontaneous ventricular arrhythmias. The first, second, and third extrastimuli (S2 through S4) conducted with progressively greater degrees of conduction delay (total activation times [TAs] of 144+/-5, 166+/-5, and 194+/-5 ms, respectively) owing to slow conduction and on occasion intramural block. The first beats of induced VT arose from subendocardial or subepicardial sites distant from areas of marked conduction delay by a focal mechanism on the basis of the absence of intervening electrical activity between the termination of the last extrastimulus and the initiation of VT (123+/-31 ms). Subsequent beats arose by a focal mechanism and conducted with a TA of 127+/-6 ms (P=NS versus initiating beats of VT [118+/-9 ms]). Spontaneous ventricular arrhythmias initiated in the subendocardium by a focal mechanism and conducted with a TA of 138+/-5 ms. Tissue analysis demonstrated a variable degree of interstitial fibrosis at sites of focal activation. Sites of conduction delay or block typically exhibited marked interstitial and/or replacement fibrosis but were spatially distant from sites initiating VT. CONCLUSIONS: Spontaneous and induced ventricular arrhythmias in patients with end-stage idiopathic cardiomyopathy can arise in the subendocardium or subepicardium by a focal mechanism.     

The effect of selenium supplementation during the early post-mating period on embryonic survival in sheep

The functioning of the guinea-pig isolated portal vein was monitored by measuring spontaneous mechanical activity, responses to electrical stimulation and administered noradrenaline in normoxic conditions. The effect of hypoxia, induced by bubbling the physiological bathing solution with a 95% N(2)/5% CO(2) gas mixture, on the mechanical performance of the vein was then assessed. Spontaneous activity declined in hypoxia, with mean contraction tension reduced by 55 + or - 8.8%. The responses to electrical field stimulation (2-32 Hz, 0.7 msec. 70 V) were lowered by 14 + or - 4.6% but contractions produced by a range of noradrenaline concentrations (0.01-160 mu M) were unaffected by hypoxia. Substitution of glucose in the bathing solution with sucrose, a substrate unavailable to the cells for energy generation, produced a marked enhancement of the effect of hypoxia. Spontaneous activity was reduced by 76 + or - 8.3%, electrically-induced activity by 80 + or - 14.4% and noradrenaline-induced responses by 85 + or - 6.8%. Although in normoxia the activity and responses of the portal vein were unaffected by the presence of alpha-tocopherol, it significantly protected the functioning of the vein in hypoxic conditions. This effect was concentration-dependent within the range 10-160 mu M and was most marked when glucose was replaced by sucrose in the bathing solution.     

Genetic factors, Na K ATPase activity and neuropathy in diabetics]

A genetic predisposition to develop a polyneuropathy in case of diabetes seems to exist. Some ethnic groups such as North Africans are prone to develop a diabetic polyneuropathy. To identify this predisposition could help in targeting a preventive treatment. We have observed that red cell Na/K ATPase activity was lower among diabetic patients than controls and even lower when diabetic neuropathy was present. Now an impaired NA/K ATPase activity has been implicated in the pathogenesis of diabetic neuropathy and ethnic differences in this enzyme activity have been demonstrated. For these reasons, we have compared red cell Na/K ATPase activity of European and North African individuals with or without diabetes and in case of diabetes with or without neuropathy. Among European subjects, Na/K ATPase activity was higher in 46 control subjects than in 84 insulin-dependent diabetic patients (405 +/- 16 nmol.mg Prot-1h-1 versus 282 +/- 10 p. < 0.05) and in the diabetic group Na/K ATPase activity was lower in the patients presenting with neuropathy (242 +/- 19 versus 323 +/- 12 p. < 0.05). The mean red cell Na/K ATPase activity was lower in 16 North African control subjects than in their European counterparts (296 +/- 26 p. < 0.05). The same observation was made when comparing 24 North Africans insulin dependent diabetic patients to the European diabetics (246 +/- 20 p. < 0.05). A low Na/K ATPase activity appears to be a risk marker of diabetic neuropathy. It could explain the propensity of North African patients to develop this diabetic complication. A restriction polymorphism exist on the first intron of the ATP1 A1 gene coding for the ATPase alpha 1 isoform. This isoform is preponderent in the nervous tissue and exclusive in red cells. Among European diabetic individuals, the presence of the restricted allele is strongly associated to diabetic neuropathy, confering a relative risk of 6.5 (95%, confidence interval 3.3-13). The restricted allele is associated to a lower Na/K ATPase activity but only among diabetic patients and not in control subjects. This fact suggests an interaction between genetic factors (the restriction polymorphism of ATP1 A1 gene) and environmental factors (diabetes) to induce a decrease in Na/K ATPase activity which in turn could favor the development of diabetic neuropathy. Among North African individuals the impairement of Na/K ATPase activity is not explained by the presence of this polymorphism. Other genetic factors remain to be identified.     

Idiopathic generalized myokymia

Idiopathic generalized myokymia (IGM) is a rare, heterogeneous, and poorly understood syndrome. We present analysis of 75 reported cases in the world literature. IGM affects men and women equally, with a mean age of onset 29 +/- 19 years. Patients' common presenting complaints are stiffness (60%), cramps (12%), weakness (12%), and muscle twitching (4%). Family history is positive in 30%. In addition to generalized clinical myokymia (92%), abnormal neurologic findings include: hyporeflexia (70%), weakness (45%), grip myotonia (39%), and calf hypertrophy (16%). Electrical activity consisting of spontaneous continuous motor unit activity and/or electrical myokymia was documented in all patients. When electrical myokymia was observed (66%), the grouped discharges where irregular and had an interburst frequency of 2-300 Hz. Both phenytoin and carbamazepine are effective treatments. We conclude that IGM has a wide spectrum of symptoms and severity and should be considered in all patients that present with stiffness, cramps, or muscle twitching. EMG greatly aids in diagnosis.     

Diagnostic yield of analysis of the pattern of electrical activity and of individual motor unit potentials in myopathy

The analysis of the pattern of electrical activity and of individual motor unit potentials in the same muscle both identified about 90% of 41 patients as having a myopathy. The pattern of electrical activity was analysed during a force which was a fixed fraction of maximum; individual motor unit potentials were analysed during weak effort. The two methods supplement each other as some of the patients were identified only by one or by the other of the two procedures. The parameter of the pattern of electrical activity which was most often abnormal was the ratio: numbers of turns to mean amplitude between turns.     

Intraoperative facial nerve monitoring (IFNM) predicts facial nerve outcome after resection of vestibular schwannoma

Intraoperative facial nerve monitoring (IFNM) is a suitable technique for intraoperative facial nerve identification and dissection, especially in large vestibular schwannomas (VS) (acoustic neuroma). To evaluate its feasibility for estimating functional nerve outcome after VS resection 60 patients underwent surgery using IFNM. Out of this group the last 40 patients were included in a prospective study evaluating the prognostic value of various IFNM parameters (proximal and distal absolute EMG amplitude, stimulation threshold, and proximal-to-distal amplitude ratio) for prediction of initial postoperative facial nerve function and recovery of function. Stimulation threshold and absolute EMG amplitude proximally at the brain stem were both predictive for postoperative nerve function. Good initial facial nerve outcome (modified House Brackmann grading, mHB degree I and degree II) was found in 15/16 patients with a proximal EMG amplitude greater than 800 microV and in 19/22 patients with proximal stimulation threshold less than 0.3 mA. Sixteen of 16 patients with proximal stimulation threshold equal to or greater than 0.3 mA had moderate-to-severe facial palsy (mHB degree III or worse). Six of six patients without evokable proximal amplitude initially had insufficient nerve function (mHB degree IV). Intraoperative decrease of the proximal amplitude was associated with an unfavourable outcome, whereas distal amplitudes usually stayed unchanged. Mean distal EMG amplitudes were also found to be decreased with poor nerve function, which may mean that the tumour had already affected the nerve. A proximal amplitude of 300 microV or less and a proximal-to-distal amplitude ratio below 1:3 were found in the absence of functional recovery in 6/8 (75%) and 5/6 (83%) patients with initial mHB degree IV, respectively. Two patients with initial mHB degree IV improved to mHB degree III despite intraoperative evidence of missing functional nerve integrity. Therefore, functional recovery cannot be predicted by IFNM in all cases of anatomical nerve preservation. We conclude that a minimum follow-up period of 1 year may still be advisable even in certain patients without evidence of intraoperative functional nerve integrity.     

Inhibition of trigeminal neurons by intravenous administration of the serotonin (5HT)1B/D receptor agonist zolmitriptan (311C90): are brain stem sites therapeutic target in migraine?

Migraine is a common and debilitating condition. Its treatment has received considerable attention in recent times with the introduction into clinical use of the serotonin (5HT)1B/D-like agonist sumatriptan. It is known from human studies that the intracranial blood vessels and dura mater are important pain-sensitive structures since mechanical or electrical stimulation of these vessels, such as the superior sagittal sinus, causes pain. We have developed a model of craniovascular pain by stimulating the superior sagittal sinus and monitoring trigeminal neuronal activity using electrophysiological techniques. In this study we determined the effect of intravenous administration of the novel anti-migraine compound zolmitriptan (311C90) upon evoked neuronal activity in trigeminal neurons. Nine adult cats were anaesthetised with alpha-chloralose (60 mg/kg, i.p.; 20 mg/kg, i.v., 2-hourly) with all surgery being conducted under halothane (1-3%). The superior sagittal sinus was isolated for electrical stimulation. Recordings were made from caudal trigeminal neurons at the C2 level of the cervical spinal cord with tungsten-in-glass microelectrodes. Signals were amplified and analysed by a custom-written program that enabled software filtering and extraction of both evoked potential and single cell data. Data were collected before and after administration of zolmitriptan. Electrical stimulation of the superior sagittal sinus resulted in activation of neuronal elements within the trigeminal nucleus that could be monitored as single unit activity or as evoked potentials, the latter reflecting both primary afferent and trigeminal cell body activity. The evoked potential recorded from the trigeminal nucleus was 207 +/- 14 microV and was reduced by zolmitriptan (100 micrograms/kg, i.v.) to a mean of 98 +/- 17 microV. Similarly, the probability of firing for trigeminal neurons was reduced from a control level of 0.63 +/- 0.1 to 0.13 +/- 0.05 after a dose of 100 micrograms/kg intravenously. These effects were dose-dependent and were significantly different from the effect of vehicle (P < 0.05). These data demonstrate that systemically administered zolmitriptan can inhibit evoked trigeminovascular activity within the trigeminal nucleus. This inhibition of trigeminal activity may play a role in the anti-migraine actions of this compound and offers the prospect of a third pathophysiologically consistent target site for anti-migraine drug effects.