Correlation between B-RAFV600E mutation and clinico-pathologic parameters in papillary thyroid carcinoma: data from a multicentric Italian study and review of the literature

Recently, a somatic point mutation of the B-RAF gene (V600E) has been identified as the most common genetic event in papillary thyroid carcinoma (PTC), with a prevalence variable among different series. Since discordant data on the clinico-pathologic features of B-RAF mutated PTC are present in the literature, the aim of the present co-operative study was to establish the prevalence of this genetic alteration and to perform a genotype-phenotype correlation in a large cohort of patients with PTC. To this purpose, a series of 260 sporadic PTCs with different histological variants were included in the study. The mutational analysis of the B-RAF gene was performed either by RT-PCR followed by single-stranded conformational polymorphism or by PCR and direct sequencing. Statistical analyses were obtained by means of chi2/Fisher's exact test and t-test. Overall, a heterozygous T > A transversion at nucleotide 1799 (V600E) was found in 99 out of 260 PTCs (38%). According to the histological type of the tumor, the B-RAF (V600E) mutation was present in 48.3% of cases of classic PTCs (85 out of 176), in 17.6% (nine out of 51) of follicular variants of PTCs, in 21.7% (five out of 23) in other PTC variants and in none of the ten poorly differentiated tumors. B-RAF (V600E) was significantly associated with the classic variant of PTC (P = 0.0001) and with an older age at diagnosis (P = 0.01). No statistically significant correlation was found among the presence of B-RAF (V600E) and gender, tumor node metastasis (TNM), multicentricity of the tumor, stage at diagnosis and outcome. In conclusion, the present study reports the prevalence of B-RAF (V600E) (38%) in the largest series of sporadic PTCs, including 260 cases from three different Italian referring centers. This prevalence is similar to that calculated by pooling together all data previously reported, 39.6% (759 out of 1914 cases), thus indicating that the prevalence of this genetic event lies around 38-40%. Furthermore, B-RAF (V600E) was confirmed to be associated with the papillary growth pattern, but not with poorer differentiated PTC variants. A significant association of B-RAF mutation was also found with an older age at diagnosis, the mutation being very rare in childhood and adolescent PTCs. Finally, no correlation was found with a poorer prognosis and a worse outcome after a median follow-up of 72 months.

Long-term functional outcome measures in corticosteroid-treated complex regional pain syndrome

AIM

The aim of this paper was to assess the effects of low-dose systemic corticosteroid therapy in complex regional pain syndrome (CRPS), to measure the long-term functional outcome, and to evaluate an arbitrary scale of severity of CRPS.

METHODS

An evaluation of 31 consecutive subjects diagnosed with CRPS before and after they underwent corticosteroid therapy was carried out. The clinical and functional variables considered were evaluated at baseline, halfway through therapy, at the end and after 1, 6 and 12 months after the end of treatment. A clinical severity scale of CRPS was devised.

RESULTS

The comparison between baseline and post-treatment data of the principal variables resulted in all cases significant (P<0.001), as did, in most cases, the changes in variables between successive time intervals (P<0.05), supporting the long-term efficacy of treatment. The score of the clinical severity scale of CRPS showed a significant improvement in the one-year follow-up.

CONCLUSION

Corticosteroid therapy in CRPS provides a short-term response to the pain with a low risk of side effects. The improvement in all the variables considered persisted at one-year follow-up. The arbitrary scale of clinical severity of CRPS should be further tested in order to propose it as an instrument for use in following the course of CRPS.

Changes in cerebral neurotransmitters and metabolites induced by acute donepezil and memantine administrations: A microdialysis study

Cholinesterase inhibitors including donepezil, rivastigmine, and galantamine and the N-methyl-D-aspartate (NMDA) antagonist, memantine are the medications currently approved for the treatment of Alzheimer's disease (AD). In addition to their beneficial effects on cognitive and functional domains typically disrupted in AD, these agents have also been shown to slow down the emergence of behavioral and psychotic symptoms associated with this disease. However, the underlying mechanisms for these therapeutic effects remain poorly understood and could involve effects of these medications on non-cholinergic or non-glutamatergic neurotransmitter systems respectively. These considerations prompted us to initiate a series of investigations to examine the acute and chronic effects of donepezil (Aricept (+/-)-2,3-dihydro-5,6-dimethoxy-2-[[1-(phenylmethyl)-4-piperidinyl]methyl]-1H-inden-1-1 hydrochloride and memantine (1-amino-3,5-dimethyladamantane hydrochloride C12H21N.HCl)). The present study focuses on the acute effects of donepezil and memantine on brain extracellular levels of acetylcholine, dopamine, serotonin, norepinephrine and their metabolites. We assayed changes in the ventral and dorsal hippocampus and the prefrontal and medial temporal cortex by microdialysis. Memantine resulted in significant increases in extracellular dopamine (DA), norepinephrine (NE), and their metabolites, in the cortical regions, and in a reduction of DA in the hippocampus. Donepezil produced an increase in extracellular DA in the cortex and in the dorsal hippocampus. Norepinephrine increased in the cortex; with donepezil it increased in the dorsal hippocampus and the medial temporal cortex, and decreased in the ventral hippocampus. Interestingly both compounds decreased extracellular serotonin (5HT) levels. The metabolites of the neurotransmitters were increased in most areas. We also found an increase in extracellular acetylcholine (ACh) by memantine in the nucleus accumbens and the ventral tegmental area. Our results suggest both region and drug specific neurotransmitter effects of these agents as well as some similarities. We conclude that drugs influencing cognitive mechanisms induce changes in a number of neurotransmitters with the changes being both region and drug specific. Release and metabolism are altered and extracellular neurotransmitter levels can be increased or decreased by the drugs. Other studies are in progress to determine the pharmacological effects associated with chronic treatment with these compounds, which may be more pertinent to the clinical situation in which patients take these medications for months or years.

Percutaneous computed tomography-guided radiofrequency thermal ablation of small unresectable lung tumours

The aim of the current study was to evaluate the safety and the efficacy of radiofrequency thermal ablation (RFTA) for the treatment of nonsmall cell lung cancer (NSCLC) and isolated pulmonary metastases (METs) from colorectal cancer (CRC). A total of 31 patients (15 with NSCLCs and 16 with CRC lung METs), with 36 lung tumour nodules (mean+/-sd diameter: 22+/-8 mm, range: 10-35 mm) underwent computed tomography (CT)-guided RFTA using expandable electrodes. Contrast-enhanced CT was performed before and after (immediately and 30+/-5 days) each RFTA session to assess immediate results and complications and repeated 3 and 6 months post-RFTA, as well as every 6 months thereafter, to evaluate long-term results. Complete radiological necrosis was defined as a nonenhancing area at the tumour site that was equal to or larger than the treated tumour; persistence of enhancement at the tumour site indicated incomplete treatment. Local recurrence was defined as an increase in tumour size and/or enhancing tissue at the tumour site. Complete radiological necrosis of the 36 tumours was achieved with 39 RFTA sessions and 42 electrode insertions. No major complications or deaths were observed. Six patients experienced mild-to-moderate pain during the procedure. There were five cases of pneumothorax, none requiring drainage and four cases of pneumonia, which were successfully treated with antibiotics. After a mean follow-up of 11.4+/-7.7 months (range of 3-36 months), the overall local recurrence rate was 13.9% (20 and 9.5% for NSCLC and CRC-METs patients, respectively). Nineteen of the 31 (61.3%) patients were alive (15 apparently disease free) and 12 (38.7%) had died (three from causes unrelated to their cancer). Radiofrequency thermal ablation seems to be a safe, effective method for producing complete ablation of small nonsmall cell lung cancers and pulmonary colorectal cancer metastases.

Abdominal spilled stones: ultrasound findings

Laparoscopic cholecystectomy (LC) is the treatment of choice for uncomplicated symptomatic gallstones. Spillage of stones due to gallbladder rupture has been reported in up to 33% of all LCs, but clinical sequelae caused by dropped gallstones are uncommon. We recently observed two patients with retained stones after LC. Correct diagnosis was made by abdominal ultrasonography (US) in both cases. In the first patient, who presented with fever, malaise, and weight loss 18 months after LC, abdominal US revealed hypoechoic focal lesions containing hyperechoic images with posterior shadowing of the liver and spleen. US-guided aspiration biopsies of these lesions yielded purulent material, and the injection and aspiration of saline solution provoked rolling movements of the hyperechoic images. Laparotomy confirmed the diagnosis of abscess-containing spilled gallstones. In the second patient, multiple hyperechoic images with posterior shadowing were observed in the Morison pouch during a routine US examination. The diagnosis of retained stones was consistent with the history of gallstone spillage during LC performed 2 months previously and was confirmed by computed tomographic findings of hyperdense images in the Morison pouch. The patient was asymptomatic, and treatment was thus deferred. Our experience suggests that US can be very useful in the detection of gallstones spilled during LC.

Distinct roles for spinophilin and neurabin in dopamine-mediated plasticity

Protein phosphatase 1 plays a major role in the governance of excitatory synaptic activity, and is subject to control via the neuromodulatory actions of dopamine. Mechanisms involved in regulating protein phosphatase 1 activity include interactions with the structurally related cytoskeletal elements spinophilin and neurabin, synaptic scaffolding proteins that are highly enriched in dendritic spines. The requirement for these proteins in dopamine-related neuromodulation was tested using knockout mice. Dopamine D1-mediated regulation of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate receptor activity was deficient in both striatal and prefrontal cortical neurons from neurabin knockout mice; in spinophilin knockout mice this deficit was manifest only in striatal neurons. At corticostriatal synapses long-term potentiation was deficient in neurabin knockout mice, but not in spinophilin knockout mice, and was rescued by a D1 receptor agonist. In contrast, long-term depression was deficient in spinophilin knockout mice but not in neurabin knockout mice, and was rescued by D2 receptor activation. Spontaneous excitatory post-synaptic current frequency was increased in neurabin knockout mice, but not in spinophilin knockout mice, and this effect was normalized by D2 receptor agonist application. Both knockout strains displayed increased induction of GluR1 Ser(845) phosphorylation in response to D1 receptor stimulation in slices, and also displayed enhanced locomotor activation in response to cocaine administration. These effects could be dissociated from cocaine reward, which was enhanced only in spinophilin knockout mice, and was accompanied by increased immediate early gene induction. These data establish a requirement for synaptic scaffolding in dopamine-mediated responses, and further indicate that spinophilin and neurabin play distinct roles in dopaminergic signal transduction and psychostimulant response.

Development of a total colonoscopy rat model with endoscopic submucosal injection of the cecal wall

BACKGROUND

Experimental models of colorectal tumor require either laparotomy for induction or anastomosis following resection. The long murine cecum avoids the need for an anastomosis, making the cecum the preferred site for induction. This study aimed to evaluate total colonoscopy with submucosal injection of cecal wall (TCWI) in rats in terms of failure rate (FR), complication rate (CR), and reproducibility (R).

METHODS

A bolus of bowel prep was given. Anesthesia was injected intraperitoneally. A video fiberscope (5.9 mm outer diameter, 180/90 degrees up/down bending, 100/100 degrees right/left bending, 103 cm working length, 120 degrees view field, and 2.0 mm channel) allowed for irrigation and suction. Saline 1 ml was injected in the cecal wall through a 4-mm-long, 23-gauge needle placed on a 3-mm wire, resulting in a blister. FR was a failure to reach and inject the cecum. Rats were allowed to recover. CR was measured at necropsy. R was assessed by comparing TCWI time, FR, and CR for three investigators. Sample size of 120 (type I error, 0.05; power, 80%) was based on a pilot study. Data are presented as median (range).

RESULTS

A total of two of 122 rats (1.6%) died after prep or anesthesia. Bowel prep resulted in 99.1% evacuation of solid feces. A total of 120 male Sprague-Dawley retired breeders weighing 592 g (range, 349-780) underwent TCWI. Scope depth was 28 cm (range, 20-36). Irrigating fluid was 290 ml (range, 100-600). TCWI time was 7 min (range, 4-28). FR was 4%. In three failed cases, the scope reached the ascending colon. CR was 2%. There were two perforations in the ascending colon. All three operators had similar TCWI time (p = 0.673), FR (p > 0.1), and CR (p > 0.1). A total of 98.3% of rats survived to planned sacrifice. At 48-h necropsy, the injection site was macroscopically identified in 118 rats.

CONCLUSIONS

A safe and reproducible TCWI rat model has been achieved, which may provide a valuable tool in the future for studies of solid colorectal tumors.

Sex differences in carpal tunnel syndrome: comparison of surgical and non-surgical populations

Carpal tunnel syndrome (CTS) patients are known to show gender-related differences in severity. The main aim of this cross-sectional study was to determine whether these differences between women and men may be related to age, education or body mass index (BMI) in two populations, one with idiopathic CTS not treated surgically and the other with idiopathic CTS treated by surgical decompression. A secondary aim was to check differences in surgical results between the genders in the surgical population. The non-surgical population consisted of 172 subjects (126 women and 46 men, mean age 55.1 years) whose data were obtained at electrophysiological examination. The surgical population consisted of 219 patients (177 women and 42 men, mean age 55.1 years) whose data were obtained before surgery. Age, education, BMI, duration of symptoms, electrophysiological and clinical severity of CTS (with ordinal scales), and the self-administered Boston Questionnaire (BQ) of symptoms and functional status of hands were considered. There were no differences in age or clinical and electrophysiological severity between women and men in either group, except for distal motor latency of the median nerve that was more delayed and duration of symptoms that was shorter in men than women in non-surgical sample. Men had a higher BMI than women. Women had higher BQ scores in the surgical and non-surgical samples. These differences remained when the results were analysed matching the men with an identical number of women of the same age, education and BMI. In the surgical population, the results of surgical decompression did not modify the gender-related differences in severity. As in many other syndromes and diseases, for a given clinical severity, women with CTS were more sensitive than men in reporting their symptoms. Risk factors of CTS, such as age, education and BMI, were not responsible for these differences. The results of surgical decompression were similar in men and women.

Can We Utilize Photorefractive Keratectomy to Improve Visual Acuity in Adult Amblyopic Eyes?

PURPOSE

To report the results of photorefractive keratectomy (PRK) in adult amblyopic patients.

DESIGN

Noncomparative case series.

PARTICIPANTS

Thirty-eight amblyopic eyes of 36 adult patients who had undergone PRK ranging from -14.63 diopters (D) to +3.75 D (mean, -6.38+/-4.10) were analyzed.

METHODS

Preoperative and postoperative (1, 3, and 6 months) refractions and measurements of the best spectacle-corrected visual acuity (BSCVA) were reviewed. Statistical evaluation was performed using a paired Student's t test.

MAIN OUTCOME MEASURES

Best-corrected visual acuity before and after PRK.

RESULTS

Before PRK, BSCVA ranged between 0.2 and 0.7 lines (mean, 0.60+/-0.13). One month after PRK, BSCVA ranged between 0.2 and 1.2 lines (mean, 0.77+/-0.24), with a significant difference (P = 3x10(-5)). Three months after PRK, BSCVA ranged between 0.15 and 1.15 lines (mean, 0.84+/-0.23), with a significant difference (P = 5x10(-7)). Six months after PRK, BSCVA ranged between 0.25 and 1.3 lines (mean, 0.88+/-0.25), with a significant difference (P = 8x10(-8)).

CONCLUSIONS

Our study does not imply that refractive surgery should or may be performed in young children but, rather, that adults wishing to undergo refractive surgery may undertake such procedures despite an amblyopic eye thought to be refractory to visual rehabilitation by conventional methods, such as spectacles and contact lenses.

The effects of cholinergic and dopaminergic antagonists on nicotine-induced cerebral neurotransmitter changes

In a continuing study of nicotine-induced mechanisms in brain areas associated with cognitive processes, the effects of cholinergic and dopaminergic antagonists on nicotine-induced changes in dopamine, norepinephrine, and serotonin were examined. These effects were measured via in vivo microdialysis in the dorsal and ventral hippocampus and in the prefrontal and medial temporal cortex of conscious, freely moving, adult male rats. Nicotine (0.3 mg/kg, free base) was administered subcutaneously and the antagonists were infused locally via the microdialysis probe. Nicotine alone induced an increase of dopamine and its metabolites in all areas, an increase of norepinephrine in the cortex, and an increase of the norepinephrine metabolite 4-hydroxy-3-methoxy-phenylglycol in all areas. Serotonin was decreased in the hippocampus and increased in the cortex. Nicotine-induced dopamine increases were inhibited by nicotinic (mecamylamine 100 microM, methyllycaconitine 500 microM), muscarinic (atropine 100 microM), and dopaminergic D1 (SCH23390 100 microM) and D2 (eticlopride 100 microM) antagonists, in the hippocampal and cortical areas. In the hippocampal areas, these antagonists had less significant effect on norepinephrine and serotonin. However, in the cortical areas, all antagonists inhibited the nicotine-induced increase of serotonin to varying degrees; and some, primarily nicotinic and dopamine D1 antagonists, inhibited the induced increase of norepinephrine. In the hippocampal and cortical areas, the mechanisms of nicotine-induced dopamine increase seem to be similar, but the mechanisms seem to be different for noradrenergic and serotonergic systems, as shown by the fact that nicotine induces no change in norepinephrine and a decrease in serotonin in the hippocampus, while it induces an increase in both in the cortex. Nicotine-induced dopamine release seems to be mediated, in part locally, by nicotinic and muscarinic receptors on dopaminergic cells. In contrast, nicotine's effect on norepinephrine and serotonin is at least partially mediated by initial changes at other than local sites, and through different receptors. Thus, the effects of nicotine and the mechanisms involved differ for different neurotransmitters and in different brain areas.

When word category information encounters morphosyntax: An ERP study

The present study investigated the relationship between two different syntactic information types, namely word category and morphosyntax. The event-related brain potential (ERP) pattern of acoustically presented sentences containing two syntactic anomalies (word category and subject-verb agreement) was compared to the ERP response to sentences containing a single violation. The ERPs for the agreement violation revealed a left anterior negativity (LAN) indicating the detection of the morphosyntactic error, followed by a P600 reflecting processes of reanalysis. The ERPs for both the category and the combined violation showed an early negativity reflecting processes of phrase structure building, followed by a P600 indicating syntactic reanalysis. Additionally, a broadly distributed negativity following the early negativity and preceding the P600 was observed. This ERP component is suggested to reflect reference specification processes arising from the specific sentence structure used in the present study. The ERP pattern for the combined violation suggests no additivity or interaction between the two syntactic anomalies in the early time windows (early negativity, reference-related negativity, and LAN), whereas interactive effects are observed in a late time range (P600).

Locally Administered Low Nicotine-Induced Neurotransmitter Changes in Areas of Cognitive Function

The present study examined the effect of a low-dose of nicotine; below that one expects to be achieved from a single cigarette, on brain regional heterogeneity and sensitivity of catecholaminergic responses. 1 microM nicotine was infused into six brain areas via a microdialysis probe: the dorsal and ventral hippocampus, the medial temporal and prefrontal cortex, the basolateral amygdala, and the ventral tegmental area (VTA). The nicotine concentration in the brain tissue near the probe site was approximately 0.1 microM. Nicotine-induced increases and decreases could be noted in dopamine (DA), norepinephrine (NE), and serotonin (5HT) levels. In particular, DA and 5HT decreased in both hippocampal areas, while NE increased in the dorsal and decreased in the ventral hippocampus. In the cortical areas, DA and NE increased and 5HT was not significantly altered. In the amygdala all three neurotransmitters increased and in the VTA, all three decreased. Many of the nicotine-induced changes in neurotransmitter concentrations were reversed in the presence of atropine. Where nicotine induced decreases in DA and 5HT in the VTA, increases were observed in the presence of atropine. A similar reversal was seen with NE in the VTA and ventral hippocampus. In contrast, the increases in DA observed in the cortex and amygdala and the increases in NE observed in the cortex, amygdala and dorsal hippocampus were inhibited by the presence of atropine. 5HT was also significantly decreased in the amygdala and both cortical areas in the presence of atropine, where nicotine alone had no significant effect. We conclude, that at low doses, nicotine significantly alters the release of DA, NE, and 5HT--in some areas increasing, in others decreasing endogenous neurotransmitter levels. This data, in conjunction with previous experiments, indicates that the effects of nicotine are regionally heterogeneous and arise from both direct and indirect actions on various receptors and neurotransmitter systems and nicotine's effects at low doses differ from that at higher doses. The changes in effects in the presence of atropine suggest that muscarinic acetylcholine receptors play a major role in nicotine's actions on neurotransmitter systems.

Bone ultrasonography in glucocorticoid-induced osteoporosis

Osteoporosis is one of the major complications of glucocorticoid (GC) therapy. Few data are available on the usefulness of quantitative ultrasound (QUS), a technique that could also theoretically provide information on bone structure, in the management of glucocorticoid-induced osteoporosis (GIO). This study aimed (1) to evaluate the ability of QUS in detecting bone impairment and in being associated with the prevalence of fragility fracture in GC patients; and (2) to assess whether QUS parameters, and particularly the graphic trace analysis of QUS signal at phalanges, show any peculiar pattern of GIO. We studied 192 patients (136 women and 56 men, mean age 56.7 +/- 14.2 years) on treatment with GCs for at least 6 months, and 192 sex- and age-matched controls. In all subjects, we measured bone mineral density (BMD) at lumbar spine and at femur by DXA, and ultrasound parameters at calcaneus and phalanges. All DXA and QUS parameters were significantly lower in GC patients than in controls and in fracture than in nonfracture GC patients. BMD at lumbar spine showed the best ability in discriminating GC patients with or without fractures. Among QUS parameters, stiffness showed a discriminatory ability significantly better than AD-SoS. BMD at lumbar spine and total femur, stiffness, and AD-SoS are able to predict the odds of fragility fracture event. QUS parameters of the postmenopausal GC patients (n = 105) and of the postmenopausal healthy controls (n = 101) were also compared with those obtained in a separate sample of 90 postmenopausal osteoporotic women (PMO). All parameters were significantly lower in GC patients and in PMO than in controls, without any significant difference between GC and PMO. Our findings show that QUS can be useful in the assessment of glucocorticoid-induced bone impairment. In addition, in this study we found no alteration in QUS parameters or in the graphic trace analysis which could differentiate between GIO and PMO. Further longitudinal studies are needed to define the role of QUS in the prediction of fracture risk and in the clinical management of GIO.

Incidence and persistence of classical swine fever in free-ranging wild boar (Sus scrofa)

Although veterinary authorities aim to limit persistence of classical swine fever (CSF) in wild boar (Sus scrofa), to avoid potential transmission to pigs, factors influencing CSF transmission and persistence are not clearly understood. Here we analyse incidence and persistence in a CSF epidemic that occurred in the French Vosges Forest. Higher incidence was found in large forests compared to smaller isolated ones, being highest near the starting point of the epidemic, but poorly related to the local density. We hypothesize that the spatial and social structure of wild boar populations may be responsible for this variability of incidence over space. Persistence was highest near the starting point of the epidemic and where initial density was highest. We hypothesize that persistence was favoured by the abundance of young wild boar, itself encouraged by CSF. Our results allow us to propose management measures aimed at limiting CSF persistence.

Medullary and papillary carcinoma of the thyroid gland occurring as a collision tumour: report of three cases with molecular analysis and review of the literature

We report the simultaneous occurrence of medullary thyroid carcinoma (MTC) and papillary thyroid carcinoma (PTC), presenting as spatially distinct and well-defined tumour components, in three cases. In the first patient, histology, immunohistochemistry and electron microscopy demonstrated an MTC in the one nodule and PTC in two additional lesions. Non-neoplastic thyroid parenchyma separated the three nodules. Metastasis from PTC was diagnosed in a regional lymph node. Genetic analysis of both tumour components showed a distinctive mutational pattern: in the MTC a Cys634Arg substitution in exon 11 of the RET gene and in the two PTC foci a Val600Glu substitution in exon 15 of the BRAF gene. The other two patients are members of a large multigenerational family affected with familial MTC due to a germline mutation of the RET gene (Ala891Ser). Both patients harboured, besides medullary cancer and C-cell hyperplasia, distinct foci of papillary thyroid cancer, which was positive for Val600Glu BRAF mutation. Review of the literature disclosed 18 similar lesions reported and allowed the identification of different patterns of clinical presentation and biological behaviour. So far, the pathogenesis of these peculiar cases of thyroid malignancy has been completely unknown, but an underlying common genetic drive has been hypothesised. This is the first report in which two mutations, in the RET and BRAF genes, have been identified in three cases of MTC/PTC collision tumour, thus documenting the different genetic origin of these two coexisting carcinomas.

CSF from MS patients can induce acute conduction block in the isolated optic nerve

In the present in vitro electrophysiological study, the acute effects of the cerebrospinal fluid (CSF) from multiple sclerosis (MS) and control subjects were measured on the axonal conduction of rat optic nerve, a central tract that is commonly affected in MS. Optic nerve compound action potential (CAP) amplitude was insensitive to the application of CSF obtained from the whole population of non-MS patients and from seven of 15 MS CSF. In the remaining eight MS cases, conversely, a time-dependent depression of CAP amplitude was observed. The reversible blockade of ion channels by soluble substances might account, at least in part, for the transient symptoms often seen in MS patients.