Accelerated atherosclerosis in ANCA-associated vasculitis.

OBJECTIVES: Cardiovascular disease, including myocardial infarction and stroke, is a major cause of mortality in ANCA-associated vasculitis (AAV). Although AAV affects small vessels, an accelerated atherosclerosis not explained by traditional cardiovascular risk factors (CVRF) has been demonstrated. We aimed to investigate the association of atherosclerosis measured by carotid intima-media thickness (CIMT) and cerebral small vessel disease in AAV-patients. MATERIALS & METHODS: Twenty-three AAV-patients in complete remission were recruited. Carotid ultrasonography (US), transcranial Doppler (TCD), brain magnetic resonance imaging (MRI), and SPECT after intravenous administration of tracer 99mTc-HMPAO (dose: 720MBq) were performed. RESULTS: AAV-patients presented higher CIMT compared to normative population. Multivariate linear regression analysis demonstrated an association of higher CIMT with increased pulsatility index in middle cerebral artery (PI-MCA) (P=.011), higher lesion load on ARWMC scale (P=.011) and abnormal SPECT (P=.008). No association between higher CIMT and CVRF (diabetes or hypertension) was demonstrated. Increasing internal carotid artery pulsatility index (PI-ICA) was associated with decreasing mean flow velocity (MFV)-MCA (P=.038), increasing PI-MCA (P=.008) and increasing white matter lesions on MRI (P=.011). CONCLUSIONS: Our study adds weight to the presence of increased atherosclerosis in AAV-patients. The association observed between CIMT and PI-ICA with small vessel cerebral disease, points the possible association of easy to use carotid US in predicting microvascular brain injury.

Long-term outcomes of adult chronic idiopathic hydrocephalus treated with a ventriculo-peritoneal shunt. / Evolución a largo plazo de la hidrocefalia crónica del adulto idiopática tratada con válvula de derivación ventrículo-peritoneal.

INTRODUCTION: Adult chronic idiopathic hydrocephalus (ACIH) is a cause of dementia that can be treated by implanting a ventriculo-peritoneal shunt (VPS). We aim to study clinical and functional outcomes in patients with ACIH corrected with a VPS. SUBJECTS AND METHODS: Observational cohort study of patients diagnosed with probable ACIH (Japan Neurosurgical Society guidelines) and undergoing shunt placement between 2008 and 2013 in a centre of reference for neurosurgery in Spain. Clinical improvement was classified in 4 categories (resolution, partial improvement, equivocal improvement, and no improvement); functional outcome was assessed on the modified Rankin scale (mRS). RESULTS: The study included 29 patients with a mean age of 73.9 years; 62.1% were male and 65.5% had hypertension. Clinical improvement (complete or partial) was observed in 58% after one year and in 48% by the end of the follow-up period (mean follow-up time was 37.8 months). Older age, presence of hypertension, and surgery-related complications were more prevalent in the group responding poorly to treatment. One patient died, 20.7% experienced severe complications, and 69% were dependent (mRS ≥ 3) by the end of the follow-up period. Age at diagnosis was independently associated with poorer clinical response at one year and a higher degree of dependency by the end of follow-up. CONCLUSION: Symptomatic benefits offered by VPS were partial and transient; treatment was associated with a high complication rate and poor functional outcomes in the long term, especially in the oldest patients.

Leukoencephalopathy due to oral methotrexate.

Methotrexate (MTX) is considered the main agent for the treatment of rheumatoid arthritis (RA). Neurotoxicity is often mild, but severe encephalopathy can develop, especially with intrathecal or intravenous administration. In rare cases, this syndrome has been observed in patients on long-term low-dose oral administration. A 68-year-old male was diagnosed with RA and on treatment with oral MTX 25 mg weekly for 4 years. The patient started with progressive dysarthria, ataxia and cognitive dysfunction. Complementary tests were normal. Magnetic resonance imaging (MRI) showed hyperintense lesions in both cerebellar hemispheres on T2-weighted and FLAIR images with a diffusion restriction on diffusion-weighted imaging (DWI) and on the apparent diffusion coefficient map (ADC). On postgadolinium T1-weighted images, there were mild enhancements. Spectroscopy showed a demyelinating pattern. A pharmacogenetics determination was made, showing a heterozygous genotype in the MTHFR and ABCB1 genes. Medication with antirheumatic drug was stopped immediately on admission, and the patient gradually improved. MTX-induced leukoencephalopathy can occur even with low-dose administration. The exact pathogenic mechanism is still unknown, but it is hypothesised that it could be the result of a cumulative toxic effect on the blood-brain barrier. The nature of the relationship between the polymorphism and CNS toxicity is still unclear, and thus, further studies are warranted. Often located in the occipital lobes, the involvement of the cerebellum is quite rare. Early recognition of the condition and withdrawal of the drug lead to a better prognosis.

Triple therapy with deferiprone, idebenone and riboflavin in Friedreich's ataxia - open-label trial.

OBJECTIVES: The objective of the study was to test the efficacy, safety and tolerability of triple therapy with deferiprone, idebenone and riboflavin in Friedreich's ataxia (FRDA) patients in a clinical pilot study. PATIENTS AND METHODS: Patients included in this study were 10 males and three females, 14-61 years of age (average 30.2 ± 12.1), diagnosed with FRDA with normal ventricular function. Patients were treated with triple therapy with deferiprone at 5-25 mg/kg/day, idebenone at 10-20 mg/kg/day and riboflavin at 10-15 mg/kg/day for 15-45 months. The efficacy of this triple therapy was assessed by change from baseline on the scale for the assessment and rating of ataxia (SARA) and by the change from baseline in echocardiogram parameters. RESULTS: Four patients discontinued due to adverse events (AEs) related with deferiprone. The annual worsening rate (AWR) was estimated in this series as 0.96 (CI 95%: 0.462-1.608) SARA score, whereas AWR for our FRDA cohort was estimated as 2.05 ± 1.23 SARA score. LVMI only decreased by 6.5 g/m(2) (6.2%) at the end of the first year of therapy. LVEF remained stable, except in case of three patients. CONCLUSION: Our results seem to indicate some uncertain benefit on the neurological and heart functions of this triple therapy in FRDA.

Autosomal recessive spinocerebellar ataxia SCAR8/ARCA1: first families detected in Spain.

INTRODUCTION: Autosomal recessive spinocerebellar ataxia type 8 (ARCA1/SCAR8) is caused by mutations of the SYNE1 gene. The disease was initially described in families from Quebec (Canada) with a phenotype of pure cerebellar syndrome, but in recent years has been reported with a more variable clinical phenotype in other countries. Cases have recently been described of muscular dystrophy, arthrogryposis, and cardiomyopathy due to SYNE1 mutations. OBJECTIVE: To describe clinical and molecular findings from 4 patients (3 men and one woman) diagnosed with ARCA1/SCAR8 from 3 Spanish families from different regions. MATERIAL AND METHODS: We describe the clinical, paraclinical, and genetic results from 4 patients diagnosed with ARCA1/SCAR8 at different Spanish neurology departments. RESULTS: Onset occurred in the third or fourth decade of life in all patients. After 15 years of progression, 3 patients presented pure cerebellar syndrome, similar to the Canadian patients; the fourth patient, with over 30 years' progression, presented vertical gaze palsy, pyramidal signs, and moderate cognitive impairment. In all patients, MRI studies showed cerebellar atrophy. The genetic study revealed distinct pathogenic SYNE1 mutations in each family. CONCLUSIONS: ARCA1/SCAR8 can be found worldwide and may be caused by many distinct mutations in the SYNE1 gene. The disease may manifest with a complex phenotype of varying severity.

Outcome of patients with amyotrophic lateral sclerosis attending in a multidisciplinary care unit.

INTRODUCTION: Amyotrophic lateral sclerosis (ALS) is a disease with very poor prognosis, and a mortality of 50% at 18 months after diagnosis. Multidisciplinary units attempt to improve the quality of life and survival of patients with ALS. The aim of this study is to evaluate every 3 months, over a 24-month period, the outcome of patients treated at the ALS unit since the time of diagnosis. MATERIAL AND METHODS: We performed a prospective observational study of patients treated in the ALS unit following a clinical pathway since the time of diagnosis with quarterly reviews from 2006 to 2010. The age of onset, functional impairment (ALSFRS-r), impairment of respiratory function, dysphagia and signs of depression and/or cognitive impairment were evaluated in relation to the initial location symptoms (bulbar [B], upper limbs [UL], lower limbs [LL]). RESULTS: A total of 42 patients (30 males and 12 females) were evaluated (mean age at onset of 57.97 years old, SD 14.56). There was an even distribution by location of onset of symptoms (B 14 patients, UL 14, LL 14.) Functional impairment (B -26,89 points, UL -22,48 points, LL -22,66 points), the need for use of BIPAP (B 64.28%; UL 35.71%; LL 50%), the presence of dysphagia (B 85.71; UL 42.85; LL 71.42%), signs of depression (B 78.57%; UL 35.71%; LL 64.28%) and cognitive impairment (B 42.85%; UL 21.42; LL 35.71%) was higher at 24 months of progression in patients with bulbar onset. There was no difference in mortality data (23.80% overall). CONCLUSIONS: The treatment in multidisciplinary units does not change the neurological progression of the disease, but increases the survival of ALS patients regardless of their initial onset, emphasising the use of multidisciplinary care.

Autosomal recessive spinocerebellar ataxia SCAR8/ARCA1: First families detected in Spain. / Heredoataxia cerebelosa recesiva ARCA1/SCAR8: primeras familias detectadas en España.

INTRODUCTION: Autosomal recessive spinocerebellar ataxia type 8 (ARCA1/SCAR8) is caused by mutations of the SYNE1 gene. The disease was initially described in families from Quebec (Canada) with a phenotype of pure cerebellar syndrome, but in recent years has been reported with a more variable clinical phenotype in other countries. Cases have recently been described of muscular dystrophy, arthrogryposis, and cardiomyopathy due to SYNE1 mutations. OBJECTIVE: To describe clinical and molecular findings from 4 patients (3 men and one woman) diagnosed with ARCA1/SCAR8 from 3 Spanish families from different regions. MATERIAL AND METHODS: We describe the clinical, paraclinical, and genetic results from 4 patients diagnosed with ARCA1/SCAR8 at different Spanish neurology departments. RESULTS: Onset occurred in the third or fourth decade of live in all patients. After 15 years of progression, 3 patients presented pure cerebellar syndrome, similar to the Canadian patients; the fourth patient, with over 30 years' progression, presented vertical gaze palsy, pyramidal signs, and moderate cognitive impairment. In all patients, MRI studies showed cerebellar atrophy. The genetic study revealed distinct pathogenic SYNE1 mutations in each family. CONCLUSIONS: ARCA1/SCAR8 can be found worldwide and may be caused by many distinct mutations in the SYNE1 gene. The disease may manifest with a complex phenotype of varying severity.

Evaluating the Calling Performance of a Rare Disease NGS Panel for Single Nucleotide and Copy Number Variants.

INTRODUCTION: Variant detection protocols for clinical next-generation sequencing (NGS) need application-specific optimization. Our aim was to analyze the performance of single nucleotide variant (SNV) and copy number (CNV) detection programs on an NGS panel for a rare disease. METHODS: Thirty genes were sequenced in 83 patients with hereditary spastic paraplegia. The variant calls obtained with LifeScope, GATK UnifiedGenotyper and GATK HaplotypeCaller were compared with Sanger sequencing. The calling efficiency was evaluated for 187 (56 unique) SNVs and indels. Five multiexon deletions detected by multiple ligation probe assay were assessed from the NGS panel data with ExomeDepth, panelcn.MOPS and CNVPanelizer software. RESULTS: There were 48/51 (94%) SNVs and 1/5 (20%) indels consistently detected by all the calling algorithms. Two SNVs were not detected by any of the callers because of a rare reference allele, and one SNV in a low coverage region was only detected by two algorithms. Regarding CNVs, ExomeDepth detected 5/5 multi-exon deletions, panelcn.MOPs 4/5 and only 3/5 deletions were accurately detected by CNVPanelizer. CONCLUSIONS: The calling efficiency of NGS algorithms for SNVs is influenced by variant type and coverage. NGS protocols need to account for the presence of rare variants in the reference sequence as well as for ambiguities in indel calling. CNV detection algorithms can be used to identify large deletions from NGS panel data for diagnostic applications; however, sensitivity depends on coverage, selection of the reference set and deletion size. We recommend the incorporation of several variant callers in the NGS pipeline to maximize variant detection efficiency.

Thermal perturbation differential spectra of ribonucleic acids. III. Chain length effect.

Thermal perturbation differential spectra of several adenylic acid oligomers, two single-strand polyribonucleotides, poly(A) and poly(C), and five trinucleoside diphosphates, U-A-A, U-A-G, U-G-A, C-U-C and C-U-A, were obtained and analysed. It is shown that these differential spectra cannot be entirely described by the nearest-neighbour approximation devised from the appropriate mononucleotides and dinucleoside monophosphates. In an attempt to determine the origin of this discrepancy, we have examined the possible optical changes arising from increased electronic interactions, changes in conformation, solvent accessibility or thermodynamic properties. This study indicates that dinucleoside monophosphates on one the hand and trinucleoside diphosphates on the other hand, are separate classes from the conformational point of view. The capacity to assume stacks, absent or negligible in higher oligomers or polymers, makes them poor models for the stacking interaction in longer nucleic acids. It is also shown that in trinucleoside diphosphates, interaction between the two terminal bases arising from bulging out of the middle base is very likely to occur. This type of interaction has to be taken into account in the description of the temperature perturbation differential spectra of trimers.

Solution structure of an oncogenic DNA duplex, the K-ras gene and the sequence containing a central C.A or A.G mismatch as a function of pH: nuclear magnetic resonance and molecular dynamics studies.

The DNA duplex 5' d(GCCACCAGCTC)-d(GAGCTGGTGGC) corresponds to the sequence 29 to 39 of the K-ras gene, which contains a hot spot for mutations. This has been studied by one and two-dimensional nuclear magnetic resonance, energy minimization and molecular dynamics. The results show that it adopts a globally B-DNA type structure. We have introduced, at the central base-pair, the mismatches C.A and A.G. The mismatch position is that of the first base of the Gly12 codon, the hot spot. For the C.A mismatch we observe a structural change as a function of pH with an apparent pKa of 7.2. At low pH, the mismatch pair adopts a structure close to a classic wobble conformation with the cytidine residue displaced into the major groove. It is stabilised by two hydrogen bonds in which the adenosine residue is protonated and the cytidine residue has a significant C3'-endo population. At high pH, the mispair structure is in equilibrium between wobble and reverse wobble conformations. Similar studies are reported on the A.G mismatch, which also undergoes a transition as a function of pH. 31P spectra have been recorded on all systems and as a function of pH. No evidence for BII phosphodiester backbone conformations was found. The NMR results are well corroborated by molecular dynamics calculations performed with or without distance constraints. The dynamics at the mismatch sites have been examined. Although the overall structures are close to B-DNA, helical parameters fluctuate differently at these sites. Different hydrogen bonding alternatives in dynamic equilibrium that can involve three-centred hydrogen bonds are observed.

Targeted screening for the detection of Pompe disease in patients with unclassified limb-girdle muscular dystrophy or asymptomatic hyperCKemia using dried blood: A Spanish cohort.

We aimed to screen for Pompe disease in patients with unclassified limb-girdle muscular dystrophy (LGMD) or asymptomatic hyperCKemia using dried blood spot (DBS) assays. Subsequently, we aimed to calculate the diagnostic delay between initial symptom presentation and the diagnosis. A prospective, multicenter, observational study was conducted in 348 patients: 146 with unclassified LGMD and 202 with asymptomatic or paucisymptomatic hyperCKemia. We quantified levels of acid alpha-glucosidase (GAA) from dried blood spots analyzed fluorometrically. The test was positive in 20 patients, and Pompe disease was confirmed by genetic testing in 16. Undiagnosed Pompe disease was detected in 7.5% of patients with LGMD and in 2.5% of patients with persistent, idiopathic elevation of serum creatine kinase. The c.-32-13 T > G mutation was found most commonly. The diagnostic delay was 15 years on average. In conclusion, DBS tests are useful and reliable screening tools for Pompe disease. We recommend the dried blood spot test to be included in the diagnostic work-up of patients with unclassified myopathies with proximal weakness and/or hyperCKemia of unknown cause and, when positive, to define the diagnosis, it will have to be confirmed by biochemical and/or molecular genetic analysis.

Mutational spectrum of the CHAC gene in patients with chorea-acanthocytosis.

Chorea-acanthocytosis (ChAc) is an autosomal recessive neurological disorder whose characteristic features include hyperkinetic movements and abnormal red blood cell morphology. Mutations in the CHAC gene on 9q21 were recently found to cause chorea-acanthocytosis. CHAC encodes a large, novel protein with a yeast homologue implicated in protein sorting. In this study, all 73 exons plus flanking intronic sequence in CHAC were screened for mutations by denaturing high-performance liquid chromatography in 43 probands with ChAc. We identified 57 different mutations, 54 of which have not previously been reported, in 39 probands. The novel mutations comprise 15 nonsense, 22 insertion/deletion, 15 splice-site and two missense mutations and are distributed throughout the CHAC gene. Three mutations were found in multiple families within this or our previous study. The preponderance of mutations that are predicted to cause absence of gene product is consistent with the recessive inheritance of this disease. The high proportion of splice-site mutations found is probably a reflection of the large number of exons that comprise the CHAC gene. The CHAC protein product, chorein, appears to have a certain tolerance to amino-acid substitutions since only two out of nine substitutions described here appear to be pathogenic.

Complement factor I deficiency associated with recurrent meningitis coinciding with menstruation.

BACKGROUND: Complement (C) factor I deficiency is a rare immunodeficiency state frequently associated with recurrent pyogenic infections in early infancy. This deficiency causes a permanent uncontrolled activation of the alternative pathway resulting in massive consumption of C3. PATIENT: A 23-year-old woman with monthly recurrent meningitis episodes, mostly in the perimenstrual period, since August 1999. Previously, at age 16 years, she had meningococcal sepsis, also coinciding with menstruation. OBJECTIVES: To study the patient and her family to elucidate the molecular defects in the pedigree and to evaluate her clinical evolution. RESULTS: We describe clinical, immunological, and treatment follow-up during this period. First, we characterized the existence of a total complement factor I deficiency defined by undetectable levels by enzyme immunosorbent assay. This total deficiency was also found in her sister. Her parents and brother had approximately half of the normal levels. In addition, the patient had very low levels of C3; factor B; and an important reduction of factor H, properdin, C5, C7, and C8 complement components. Additional studies in the patient's sera evidenced high levels of immune complexes containing C1q and immunoglobulin (Ig) G, as well as C3b/factor H, C3b/properdin, C3b/IgG, and properdin/IgG complexes. Treatment with prophylactic antibiotics, antiestrogen medication, plasma infusions, or intravenous immunoglobulin has been unsuccessful in avoiding consecutive meningitis episodes. CONCLUSION: For the first time to our knowledge, these data present an unusual relationship between meningitis episodes and menstruation in factor I immunodeficiency.

Abnormal sensory nerve conduction in multifocal demyelinating neuropathy with persistent conduction block.

Two patients exhibited chronic, slightly asymmetric weakness and wasting with fasciculations of the upper limb and hand muscles. Motor nerve conduction studies showed features of multifocal conduction block in nerve segments other than those usually involved in entrapment syndromes. The F wave was markedly delayed in the median and ulnar nerves. Transcranial cortical and cervical root magnetic stimulation showed bilaterally delayed thenar responses with normal central conduction time. Needle electromyography demonstrated a chronic denervation pattern with large polyphasic motor units in several muscles of the upper limbs. Sensory symptoms were mild and limited to paresthesias in the fingertips. Sensory nerve conduction velocity and sensory nerve action potential amplitudes were normal in elbow-to-wrist and wrist-to-finger segments of the median and ulnar nerves, but there was a delayed cortical response and unrecognizable Erb's point and cervical responses in the somatosensory evoked potentials to median nerve electrical stimulation. Electrophysiologic examination was normal in most nerves of the lower limbs. These two patients, meeting clinical and electrophysiologic criteria of multifocal neuropathy with conduction block, demonstrate that sensory fibers may also be involved in this syndrome.

Autoantibodies to glutamic acid decarboxylase in three patients with cerebellar ataxia, late-onset insulin-dependent diabetes mellitus, and polyendocrine autoimmunity.

BACKGROUND: Glutamic acid decarboxylase (GAD) is the main target of humoral autoimmunity in stiff-man syndrome (SMS) and insulin-dependent diabetes mellitus (IDDM). GAD autoantibodies (GAD-Abs) are reported in a few patients with cerebellar ataxia, but their relevance is unclear. We describe three patients with cerebellar ataxia and GAD-Abs. METHODS: GAD-Abs were assayed by radioimmunoassay (RIA) and immunohistochemistry and confirmed by immunoblot of recombinant human GAD65. The GAD-Ab levels of the three patients with cerebellar ataxia were compared with those of five with SMS, 49 with IDDM, 64 with cerebellar ataxia of probable degenerative origin without associated autoimmune features, 14 non-IDDM islet cell antibody-positive first-degree relatives of IDDM patients, and 91 normal subjects. RESULTS: The three patients with ataxia and GAD-Abs were women (mean age, 63 years) with an isolated progressive cerebellar disorder, family history of IDDM, late-onset IDDM, and several positive serum organ-specific autoantibodies. Two patients had autoimmune thyroiditis, and one had pernicious anemia. CSF analysis demonstrated oligoclonal IgG bands and intrathecal synthesis of GAD-Abs. By RIA, GAD-Ab titers from the three patients were similar to those of SMS and significantly higher, without overlap, than the titers of IDDM patients. GAD-Abs were absent in the 64 patients with cerebellar ataxia and no evidence of autoimmune disorders. CONCLUSIONS: These findings suggest a link of GAD autoimmunity not only with SMS but also with cerebellar dysfunction. GAD-Abs should be sought in patients with cerebellar ataxia who have late-onset IDDM and other organ-specific autoimmune manifestations.

The hierarchical approach to the DNA stability problem. I. Patterns in non-equilibrium denaturation and renaturation.

As proposed by Azbel (Phys. Rev. Letters, 1973, 31, 589-592), DNA sequences may be uniquely divided into embedded segments with different lengths and stabilities, each of them a potential denaturation unit. This "hierarchical" approach to the DNA stability problem was originally devised for the analysis of equilibria situations. We have extended it to deal quantitatively with various locally irreversible denaturation/renaturation processes that play a leading part in most actual experiments. Special emphasis is placed on (1) describing and delimiting major experimental domains with respect to reversibility/irreversibility, and (2) the quantitative treatment of bidirectional denaturation processes which are shown to lend themselves to an original, hierarchical analysis.

The hierarchical approach to the DNA stability problem. II. Some applications and speculations with yeast mitochondrial DNA as an example.

As discussed in the preceding article [1] hierarchical analysis of DNA sequences should make it possible to treat complex unfolding (and refolding) processes involving both equilibrium and non-equilibrium subtransitions. Hence a variety of actual experimental situations may be analyzed. This is demonstrated with the help of a 1950 bp yeast mitochondrial DNA sequence encompassing part of the 21S ribosomal RNA gene: excellent fit of complex denaturation and renaturation profiles is achieved with only two adjustable parameters. The advantage of dealing with objectively defined stability units is also apparent when stability profiles are compared to known functional maps: striking correlations may be brought out and their possible significance is briefly discussed.

About the large fluctuations observed using gas-phase molecular dynamics in the K-ras gene containing a mismatch.

We describe how we can reduce the periodic bending motions in the simulation in vacuo of the molecular dynamics of a short DNA fragment containing the Gly 12 hot spot of the K-ras oncogene and having at its center a mismatch CA+.

IgG anti-ganglioside antibodies and their subclass distribution in two patients with acute and chronic motor neuropathy.

IgG anti-ganglioside antibodies were found in two patients with motor neuropathy. The first patient had a chronic axonal neuropathy with persistently elevated anti-GM1 antibodies. The second patient had an acute axonal neuropathy with anti-GM1, GD1b and asialoGM1 antibodies. In both, the IgG subclass study showed that the antibodies belonged to the IgG1 subclass. An enzyme-linked immunosorbent assay (ELISA) for light chains revealed anti-ganglioside antibodies of the lambda type.

Re-examination of the effects of raphe lesions on the sleep/wakefulness cycle states in cats.

To study the specific effects of central superior raphe nucleus (CeSR) lesions on the different sleep/wakefulness cycle states of the cat, nine animals with implanted electrodes for EOG, EMG and EEG recordings were used. Seven cats received diathermocoagulation lesions that destroyed between 13 and 100 percent of the CeSR; the remaining two cats, which suffered lesions in the paramedial region of the oral pontine reticular nucleus (RPO), were used to determine the effects on sleep/wakefulness states caused by damage to adjacent CeSR structures and/or passage fibres. Three prelesion and five postlesion weekly 24 h recordings were obtained from each cat. Recordings were scored according to the polygraphic criteria for wakefulness (W), drowsiness (D), slow wave sleep (SWS) and paradoxical sleep (PS). Results indicated that insomnia is not produced exclusively by CeSR lesions, since adjacent paramedial RPO lesions also decrease both SWS and PS; however, increased W occurred after the former while increased D occurred after the latter. Correlation coefficient analyses showed that W is the only state that correlates significantly with the volume of CeSR destroyed. The following correlations between different states of the sleep/wakefulness cycle were, however, significant: W-D, W-SWS and SWS-PS. Disinhibition of W, therefore, and not sleep loss seems to be the primary effect of CeSR lesions. Thus, the CeSR nucleus appears to be involved in arousal mechanisms rather than in direct sleep promotion.