Effect of magnesium on nerve conduction velocity during regular dialysis treatment

Serial nerve conduction velocities in the peroneal and ulnar nerves have been measured in 10 patients on regular dialysis treatment over a three year period. Each patient alternated between phases on dialysis with magnesium-containing dialysate (1·5-1·7 m-equiv/l.) and phases on `magnesium-free' dialysate (0·2 m-equiv/l.). Plasma magnesium concentrations were high both pre- and post-dialysis during magnesium-containing dialysis, and normal to low on magnesium-free dialysis. All patients had defects in nerve conduction, mainly asymptomatic. Increases in nerve conduction velocity coincided with magnesium-free dialysis, and decreases occurred when the patients reverted to magnesium-containing dialysate. The significance of the correlation by the sign test was P<0·0005. It is concluded that extracellular magnesium levels can influence the rate of nerve conduction in vivo.     

Normal sensory conduction in the nerves of the leg in man

For comparison with findings in neuropathy, sensory conduction was studied along distal and proximal segments of the superficial peroneal, sural, and posterior tibial nerves in 71 healthy subjects 15 to 72 years of age and normal values were established (Table 2). In the distal segments of the nerves of the leg the amplitudes of the sensory potentials were one tenth those in the nerves of the upper extremity; the potentials were split up into several components, and electronic averaging was used routinely to analyse the shape of the potentials. The maximum sensory conduction velocity was 56·5 m/sec, SD 3·4 m/sec, in proximal; and 46·1 m/sec, SD 3·7 m/sec, in distal segments of the nerves (subjects 15 to 30 years, 34 to 36°C). Slowing of conduction with increasing age was the same proximally and distally (subjects 40 to 65 years: proximally 53·1 m/sec, SD 4·6 m/sec; distally 42·5 m/sec, SD 5·5 m/sec, 34 to 36°C). The velocity in the slowest components of the sensory potentials averaged 20 m/sec. The sensory velocity was 3 to 6 m/sec faster than the motor. The error arising from measuring the conduction distance on the surface across the capitulum fibulae was evaluated.     

Abnormalities of taste and smell after head trauma

Abnormalities of taste and smell were studied in 29 patients after head trauma. These abnormalities included decreased taste acuity (hypogeusia), a distortion of taste acuity (dysgeusia), decreased smell acuity (hyposmia), and a distortion of smell acuity (dysosmia). This syndrome can occur even after minimal head trauma and can begin months after the moment of injury. The patients exhibited a significant decrease in total serum zinc concentration (patients, 77 ± 3 μg/100 ml, mean ± 1 SEM, vs controls, 99 ± 2 μg/100 ml, P>0·001) and a significant increase in total serum copper concentrations (113 ± 4 μg/100 ml vs 100 ± 2 μg/100 ml, P<0·001) compared with control subjects. Symptoms of hypogeusia, dysgeusia, and dysosmia are frequent sequelae of head injury and are important to the patients and to their care after trauma.     

Carcinomatous neuromyopathy: 2. Immunological studies: An electrophysiological and immunological study of patients with carcinoma of the lung

Significant cellular sensitivity to peripheral nerve antigens was found by MIF assay in 36% of patients with lung cancer (P<0·005) as compared with 62% of patients with peripheral neuropathy without neoplasia. No sensitivity was found in controls or the cancer sub-group without neuromuscular abnormality. The significance of these findings for an immune mechanism is discussed.     

Sensory conduction in peroneal and posterior tibial nerves using averaging techniques

A method of obtaining pure sensory nerve conduction velocities in the lower extremities is described. This involves the use of electronic summation (signal averaging). Potentials were obtained and velocities calculated from all normal subjects examined. In patients with peripheral neuropathies it was often possible to obtain nerve velocities with signal amplitudes as low as 0·1 μV and these were often slower than those obtained from the normal subjects. The advantages and disadvantages of this method are discussed. It is of significant clinical value in that pure sensory nerve conduction velocities can be measured in the legs when this may be the only valuable parameter in the absence of motor involvement. In addition, investigation of neuropathies at an earlier stage of development and recovery may be facilitated. It is hoped that in the future this technique of obtaining low amplitude responses with an analogue averager can be incorporated with the more routine aspects of nerve conduction testing when clinically indicated.     

Ulnar nerve lesions associated with the carpal tunnel syndrome

Electrophysiological studies were performed on median and ulnar nerves in 234 cases of carpal tunnel syndrome. Abnormalities of the ulnar nerve sensory action potential were found in 39·3% of cases. The amplitude of the ulnar nerve sensory action potential was related to the amplitude of the median nerve sensory action potential, and to the median nerve motor conduction velocity in the forearm. The findings suggest that in a significant proportion of patients with carpal tunnel syndrome, a more generalized subclinical neuropathy may be present.     

Differential cellular increase in cerebrospinal fluid after encephalography in mentally retarded patients

The behaviour of the CSF cells during gas encephalography (GEG) with O₂, N₂O, and halothane is poorly known in cerebral developmental disorders. One hundred and fifty CSF samples taken during pneumoencephalography from 75 mentally retarded patients were examined cytologically by the millipore technique with Papanicolaou staining. The results were processed automatically. An approximately 25-fold increase in CSF cells (P<0·001), mainly meningeal, reticulohistiocytic, and monocytic types, was found to occur. The cortical gas filling rate had a positive correlation (P<0·001) with the increase of number of CSF cells. There were no significant differences between the cellular changes in different cerebral disorders. Thus, though the irritant effect of GEG gives a rich cell yield, diagnostic atypical cells in developmental disorders of the central nervous system probably rarely exfoliate into the lumbar CSF.     

Sensory evoked potentials in Guillain-Barré polyneuropathy.

In 11 patients with acute Guillain-Barré polyneuropathy examined within 2 weeks of the onset of the paralysis, sensory evoked potential techniques were able to demonstrate a proximal conduction delay between Erb's point and the cervical cord in 10 subjects; while sensory conduction distal to Erb's point was much more commonly normal in the early period. Sensory evoked potential techniques provide therefore a valuable way to demonstrate proximal conduction velocity slowing early in the course of this disease.     

Are hypertrophic astrocytes a sufficient criterion of perinatal telencephalic leucoencephalopathy?

To determine if the presence of amphophilic globules (GL) in infant cerebral white matter was a necessary criterion of perinatal telencephalic leucoencephalopathy (PTL), the epidemiological features of infants who had PTL—that is, hypertrophic astrocytes and amphophilic globules (HA·GL)—in their cerebral white matter were compared with those of infants who had hypertrophic astrocytes, but who did not have amphophilic globules (HA·[unk]). Postmortem bacteraemia was seen much more frequently in infants with HA·GL than in infants with HA·[unk] (P<0·05). In addition, infants with HA·GL tended to die at older postnatal ages than infants with HA·[unk]. These observations are in keeping with the view that HA·GL and HA·[unk] are not epidemiologically identical. The operational definition of PTL therefore remains the occurrence of both HA and GL in infant cerebral white matter.     

Sensory conduction from digit to palm and from palm to wrist in the carpal tunnel syndrome

In normal subjects the maximum and minimum conduction velocity along sensory nerve was the same from digit to palm and from palm to wrist. Severe slowing from palm to wrist in patients with the carpal tunnel syndrome was often associated with only slight slowing from digit to palm. The distal slowing is attributed to a reversible constriction of nerve fibres, an assumption supported by the recovery in distal conduction velocity as early as two and a half months after decompression. The sensory velocity from wrist to elbow was normal or supernormal, whereas the motor velocity was often slightly decreased. The exclusion of the normal segment of the median nerve distal to the flexor retinaculum made it possible to demonstrate abnormalities across the flexor retinaculum in patients with clinical signs of carpal tunnel syndrome in whom distal motor latency and sensory conduction from digit to wrist were normal.     

Cerebral blood flow, internal carotid artery pressure, and the EEG as a guide to the safety of carotid ligation

Twenty patients with aneurysms of the internal carotid artery underwent temporary clamping, in turn, of the internal and then the common carotid artery. Cerebral blood flow, internal carotid artery pressure, and the EEG were recorded to assess the probability of cerebral ischaemia after permanent ligation. With this method of monitoring the cerebral circulation, 17 of the 20 patients had a permanent carotid ligation without neurological deficit; in the other three ligation was contraindicated. Although a correlation was observed between the reduction of cerebral blood flow and the fall in internal carotid artery pressure caused by temporary clamping (P<0·01), the scatter of data was too wide to predict cerebral blood flow from the change in carotid artery pressure. Similarly, EEG slowing was usually associated with low cerebral blood flow but exceptions occurred. Ligation was safe when, during temporary clamping, cerebral blood flow exceeded 40 ml/100 g/min, but was deemed unsafe when flow was less than 20 ml/100 g/min. In the range 20-40 ml/100 g/min, consideration of the internal carotid artery pressure permitted more patients to be safely ligated than if the decision had rested on changes in cerebral blood flow alone.     

Medial dorsal superficial peroneal nerve studies in patients with polyneuropathy and normal sural responses

We studied medial dorsal superficial peroneal (MDSP) nerves in 52 patients with clinical evidence of mild chronic sensorimotor polyneuropathy and normal sural nerve responses, in order to assess the diagnostic sensitivity and usefulness of MDSP nerve testing in electrodiagnostic practice. To determine the effect of age on MDSP nerve parameters, 98 normal subjects were also examined. Electrodiagnostic evaluation involved studies of motor nerve conduction in tibial, peroneal, and median nerves; sensory nerve conduction in sural, MDSP, median, and radial nerves; tibial and peroneal nerve F waves; H reflexes from the soleus muscles; and needle electromyography of gastrocnemius and abductor hallucis muscles. Among the patients, 49% had low-amplitude sensory responses in MDSP nerves and 57% had either slowing of sensory conduction velocity or no sensory responses on proximal stimulation. MDSP nerve amplitude, tibial nerve motor velocity, and H reflexes were the most sensitive for detection of mild chronic symmetrical axonal sensorimotor polyneuropathy. MDSP nerve testing should be included in the routine electrodiagnostic evaluation of patients with suspected polyneuropathy and normal sural nerve responses.     

Intracerebral temperature in patients with hydrocephalus of varying aetiology

Brain temperature was measured at various depths beneath thepial surface in patients with hydrocephalus of varying aetiology. Temperature increased gradually with depth in all patients, with thehighest temperature found in the ventricle. The difference betweenintraventricular and rectal temperatures (Δv-r) was greater inpatients who underwent continuous ventricular drainage than in patientswho underwent ventriculoperitoneal shunt (continuous ventriculardrainage; 1.2 (SD 0.40)°C, mean (SD), n=5 vventriculoperitoneal shunt; 0.4 (SD 0.45)°C, n=16; p< 0.05). Thedifference between intracerebral and rectal temperatures (Δb2-r) wasalso greater in patients with continuous ventricular drainage than inpatients with ventriculoperitoneal shunt (continuous ventriculardrainage; 0.1 (SD 0.86)°C, n=5 v ventriculoperitonealshunt; −0.7 (0.86)°C, n=16; p< 0.05). Among patients with normalpressure hydrocephalus, these differences were greater in the patientswith better outcomes after shunt surgery than in the less improvedgroup (Δv−r; 0.7(SD 0.27)°C, n=7 v 0.1 (SD0.40)°C, n=5, p< 0.01, Δb2-r; −0.2 (SD 0.61)°C, n=7v−1.4 (0.90)°C, n=5, p< 0.01).

     

Prevalence of subclinical neuropathy in diabetic patients: assessment by study of conduction velocity distribution within motor and sensory nerve fibres

Nerve conduction velocity distribution (CVD) study is a newly-developed electrodiagnostic method for detecting alterations in the composition of nerve fibres according to their conduction velocity. The presence of subclinical neuropathy was evaluated in 138 diabetic patients by CVD study of four motor nerves (external popliteal and ulnar nerves bilaterally) and two sensory nerves (median nerve bilaterally), and the data obtained were compared with standard electrophysiological parameters in the same nerve segments. CVD studies revealed an altered distribution pattern in 106 of 129 evaluable patients for motor nerves (82%) and in 67 of 115 evaluable patients for sensory nerves (58%), while standard examination gave abnormal findings in 92 of 137 patients (67%) and in 33 of 118 patients (11%), respectively. Of the patients adequately evaluated by both techniques, 21 of 129 patients (16%) revealed altered CVD data unaccompanied by slowing of maximum nerve conduction velocity, and 37 patients of 101 (37%) showed similar findings for sensory nerves. Subclinical alterations of motor and sensory nerve CVD were not significantly related to age or to metabolic control expressed as glycated haemoglobin levels; a significantly longer duration of disease was found in patients with motor and mixed subclinical neuropathy with respect to non-neuropathic patients. The CVD study allowed us to detect subclinical abnormalities of motor and sensory nerve fibres; often this is a more sensitive method than the standard electrodiagnostic study. This method can be very useful as a diagnostic tool and in research in the study of the progression of diabetic neuropathy. Received: 21 March 1997 Received in revised form: 8 September 1997 Accepted: 7 October 1997     

Blood flow distribution during heat stress: cerebral and systemic blood flow

The purpose of the present study was to assess the effect of heat stress-induced changes in systemic circulation on intra- and extracranial blood flows and its distribution. Twelve healthy subjects with a mean age of 22±2 (s.d.) years dressed in a tube-lined suit and rested in a supine position. Cardiac output (Q), internal carotid artery (ICA), external carotid artery (ECA), and vertebral artery (VA) blood flows were measured by ultrasonography before and during whole body heating. Esophageal temperature increased from 37.0±0.2°C to 38.4±0.2°C during whole body heating. Despite an increase in Q (59±31%, P<0.001), ICA and VA decreased to 83±15% (P=0.001) and 87±8% (P=0.002), respectively, whereas ECA blood flow gradually increased from 188±72 to 422±189 mL/minute (+135%, P<0.001). These findings indicate that heat stress modified the effect of Q on blood flows at each artery; the increased Q due to heat stress was redistributed to extracranial vascular beds.     

Bimoclomol (BRLP-42) Ameliorates Peripheral Neuropathy in Streptozotocin-Induced Diabetic Rats

A reduction in nerve conduction velocity and an increase in resistance to ischemic conduction failure are early signs of neural dysfunction in both diabetic patients and animal models of diabetes. The effect of Bimoclomol (BRLP-42), a drug under clinical development for the treatment of diabetic complications, on experimental peripheral neuropathy was examined in rats made diabetic by injection of streptozotocin. Daily oral doses of Bimoclomol (10 or 20 mg/kg) or control dose of γ-linolenic acid (260 mg/kg), an agent with known neuropathy-improving effects, were administered for 3 months. Treatments began 1 day after diabetes induction to assess the prophylactic efficacy of Bimoclomol. Neuropathy was evaluated electrophysiologically by measuring motor and sensory nerve conduction velocities and resistance to ischemic conduction failure of sciatic nerve in vivo. Bimoclomol significantly reduced nerve conduction slowing and retarded the typical elevated ischaemic resistance due to streptozotocin-induced neuropathy, suggesting that the drug might be a useful treatment for diabetic peripheral neuropathies.     

Sensory action potentials and biopsy of the sural nerve in neuropathy.

In 167 consecutive patients with various types of neuropathy, the amplitude of the sensory potential and the maximum conduction velocity along the sural nerve were compared with conduction in other sensory nerves, and were related to structural changes revealed by nerve biopsy. Electrophysiological findings in the sural nerve were similar to those in the superficial peroneal and the median nerve, though the distal segment of the median nerve was normal in 20 per cent of the patients when it was abnormal in the sural nerve. Quantitation of histological findings was a more sensitive method than the electrophysiological study in that two-thirds of 33 patients with normal electrophysiology in the sural nerve showed mild loss of fibres or signs of remyelination in teased fibres. The amplitude of the sensory potential was grossly related to the number of large myelinated fibres (more than 7 micrometer in diameter). Considering the 95 nerves from which teased fibres were obtained, maximum conduction velocity was abnormal in half. In 18 of these nerves, slowing in conduction was due to axonal degeneration: the velocity was as to be expected from the diameter of the largest fibres in the biopsy ("proportionate slowing"). In 9 nerves slowing was severe and more marked than to be expected from loss of the largest fibres ("disproportionate slowing"); these nerves showed paranodal or segmental demyelination in more than 30 per cent of the fibres. In 16 nerves from patients with neuropathy of different aetiology neither loss of fibres nor demyelination could explain the moderate slowing. The cause of slowing in these nerves is unknown; other conditions are referred to in which slowing in conduction cannot be attributed to morphological changes. Finally, electrophysiological and histological findings are reported in some patients with neuropathy associated with malignant neoplasm, with rheumatoid arthritis, with polyarteritis nodosa, with acute intermittent porphyria and with cirrhosis of the liver.     

Respective importance of different nerve conduction velocities in leprosy

Motor and sensory nerve conduction studies were performed in the distal part of the ulnar, median and radial nerves of 12 tuberculoid and 12 lepromatous leprosy patients, compared with 15 normal subjects. Slowing of sensory conduction velocity (SCV) was shown in all nerves with no difference between tuberculoid and lepromatous patients. The radial SCV slowing is correlated (P < 0.001) with the clinical findings. Impairment of motor distal latencies was observed only in tuberculoid patients. It is concluded that the radial SCV is the most reliable conduction test and is proposed as an early diagnostic test for leprosy.     

Linoleate metabolism in multiple sclerosis

(1) The levels of oleate and linoleate in the serum have been measured in 14 patients with multiple sclerosis (MS) and in 14 healthy subjects before, during and after a five day period when the normal diet was supplemented with linoleate. (2) In confirmation of earlier work the mean percentage of linoleate in the serum lipids of the MS patients was significantly lower (P < 0·01) than in the control subjects in the pre-supplementation period. The mean percentage of oleate showed an increase (P < 0·005) in the patients as compared with the controls while on their normal diets. (3) The period of linoleate feeding produced a considerable rise in the percentage of linoleate together with a fall in the percentage of oleate in both the controls and the MS patients. (4) When large amounts of linoleate, as present in sunflower seed oil, are ingested we have been unable to obtain evidence of a defect in absorption from the intestinal lumen.     

Amyloid‐β protein and MicroRNA‐384 in NCAM‐Labeled exosomes from peripheral blood are potential diagnostic markers for Alzheimer's disease

ObjectiveWe aimed to establish a method to determine whether amyloid‐β (Aβ) protein and miR‐384 in peripheral blood neural cell adhesion molecule (NCAM)/ATP‐binding cassette transporter A1 (ABCA1) dual‐labeled exosomes may serve as diagnostic markers for the diagnosis of Alzheimer''s disease (AD).MethodsThis was a multicenter study using a two‐stage design. The subjects included 45 subjective cognitive decline (SCD) patients, 50 amnesic mild cognitive impairment (aMCI) patients, 40 AD patients, and 30 controls in the discovery stage. The results were validated in the verification stage in 47 SCD patients, 45 aMCI patients, 45 AD patients, and 30 controls. NCAM single‐labeled and NCAM/ABCA1 double‐labeled exosomes in the peripheral blood were captured and detected by immunoassay.ResultsThe Aβ42, Aβ_42/40, Tau, P‐T181‐tau, and miR‐384 levels in NCAM single‐labeled and NCAM/ABCA1 double‐labeled exosomes of the aMCI and AD groups were significantly higher than those of the SCD, control, and vascular dementia (VaD) groups (all p < 0.05). The Aβ42 and miR‐384 levels in NCAM/ABCA1 dual‐labeled exosomes of the aMCI and AD groups were higher than those of the control and VaD groups (all p < 0.05). The exosomal Aβ42, Aβ_42/40, Tau, P‐T181‐tau, and miR‐384 levels in peripheral blood were correlated with those in cerebrospinal fluid (all p < 0.05).ConclusionThis study, for the first time, established a method that sorts specific surface marker exosomes using a two‐step immune capture technology. The plasma NCAM/ABCA1 dual‐labeled exosomal Aβ_42/40 and miR‐384 had potential advantages in the diagnosis of SCD.