European neuroborreliosis: quality of life 30 months after treatment

OBJECTIVES

The prognosis after Lyme neuroborreliosis (LNB) is debated. The aim of this study was to assess health-related Quality of Life (QoL) and neurological symptoms 30 months after treatment in European patients with LNB.

MATERIALS AND METHODS

In a prospective case-control designed study, we investigated 50 well-characterized patients with LNB who had participated in a treatment trial for LNB 30 months earlier and 50 matched control persons with the health QoL questionnaire Short-Form 36 (SF-36), the Fatigue Severity Scale (FSS), the Montgomery and Åsberg Depression Rating Scale (MADRS), the Starkstein Apathy Scale (SAS), and the Mini Mental State (MMS). Clinical and demographic data were collected by semi-structured interviews and clinical neurological examination.

RESULTS

Lyme neuroborreliosis-treated patients scored lower than control persons in the SF-36 domains physical component summary (PCS) (44 vs 51 P < 0.001) and mental component summary (MCS) (49 vs 54 P = 0.010). They also scored lower than control persons in all the SF-36 subscales, except for bodily pain, and on FSS (3.5 vs 2.1 P < 0.001), but not on MMS (28 vs 29 P = 0.106). There was a difference in MADRS (3.1 vs 0. 8 P = 0.003) and SAS (13 vs 11 P = 0.016), but the scores were low in both groups. Fatigue was the most frequently reported symptom among LNB-treated patients (50%). Patients who reported complete recovery (56%) after LNB had similar QoL scores as the controls.

CONCLUSION

European persons treated for LNB have poorer health-related QoL and have more fatigue than persons without LNB.

European neuroborreliosis: neuropsychological findings 30 months post-treatment

BACKGROUND

The aim of this study was to compare neuropsychological (NP) functioning in patients with Lyme neuroborreliosis (LNB) 30months after treatment to matched controls.

METHODS

We tested 50 patients with LNB and 50 controls with the trail-making test (TMT), Stroop test, digit symbol test, and California Verbal Learning test (CVLT). A global NP sumscore was calculated to express the number of low scores on 23 NP subtasks.

RESULTS

Mean scores were lower amongst LNB-treated patients than amongst controls on tasks assessing attention/executive functions: (Stroop test 4: 77.6 vs. 67.0, P=0.015), response/processing speed (TMT 5: 23.4 vs. 19.2, P=0.004), visual memory (digit symbol recall: 6.6 vs. 7.2, P=0.038), and verbal memory (CVLT list B: 4.68 vs. 5.50, P=0.003). The proportion of patients and controls with NP sumscores within one SD from the mean in the control group (defined as normal) and between one and two SD (defined as deficit) were similar, but more LNB-treated patients than controls had a sumscore more than two SD from the mean (defined as impairment) (8 vs. 1, P=0.014).

CONCLUSIONS

As a group, LNB-treated patients scored lower on four NP subtasks assessing processing speed, visual and verbal memory, and executive/attention functions, as compared to matched controls. The distribution of NP dysfunctions indicates that most LNB-treated patients perform comparable to controls, whilst a small subgroup have a debilitating long-term course with cognitive problems.

Multiple sclerosis in Vest-Agder County, Norway

OBJECTIVE

To examine multiple sclerosis (MS) prevalence, rate of immunomodulatory treatment and frequency of Borrelia burgordorferi (Bb) antibodies in Vest-Agder, Norway.

MATERIALS AND METHODS

Patients in the period 1996-2006 who met the Poser criteria for definitive or probable MS were included. Clinical and demographical data, and presence of Bb antibodies were registered.

RESULTS

A total of 295 patients were identified. The crude prevalence was 180 per 100,000 population (95% CI=160.9-218.0), age-adjusted prevalence was 186 per 100,000 population (95% CI=166.3-225.3). The age-adjusted incidence rates were 7.5 and 8.0 for 1996-2000 and 2001-2006, respectively. Thirty-eight per cent were treated with immunomodulatory agents when compared to 28% in the rest of the country. Bb serum antibodies were detected in 7% of patients with MS.

CONCLUSIONS

Vest-Agder county has the highest prevalence of MS reported in Norway, and a high treatment rate. Bb antibodies were not more prevalent than in healthy individuals.

Remaining complaints 1 year after treatment for acute Lyme neuroborreliosis; frequency, pattern and risk factors

BACKGROUND AND PURPOSE

To chart remaining complaints 1 year after treatment for neuroborreliosis, and to identify risk factors for a non-favorable outcome.

METHODS

We followed patients treated for neuroborreliosis prospectively, and assessed outcome by a composite clinical score. The impact on outcome of clinical, demographic and laboratory factors were analyzed by univariate analyses and logistic regression.

RESULTS

Out of 85 patients 41 (48%) had remaining complaints; 14 had objective findings and 27 subjective symptoms. Remaining complaints were associated with pre-treatment symptom duration >or=6 weeks (OR = 4.062, P = 0.044), high pre-treatment cerebrospinal fluid (CSF) cell count (OR = 1.005, P = 0.001), and female gender (OR = 3.218, P = 0.025). Presence of CSF oligoclonal bands (OCBs) was not analyzed in the logistic regression model due to many missing observations, but was found to be more frequent both pre-treatment (P = 0.004) and after 12 months (P = 0.015) among patients with remaining complaints as compared to patients with complete recovery. Further evaluation showed that objective remaining findings, and not subjective symptoms, were associated with pre-treatment symptom duration >or=6 weeks. No difference in outcome was observed between patients treated with IV ceftriaxone and patients treated with oral doxycycline.

CONCLUSION

Remaining complaints are common after neuroborreliosis. The majority of the complaints are subjective. Pre-treatment symptom duration >or=6 weeks, high pre-treatment CSF cell count, and female gender seem to be risk factors for remaining complaints. Presence of CSF OCBs may also predict a non-favorable outcome, but this should be further studied. Whether subjective and objective complaints are associated with different risk factors is also an issue for future studies.

Clinical usefulness of intrathecal antibody testing in acute Lyme neuroborreliosis

The aim of the study was to examine diagnostic sensitivity and temporal course of intrathecal Borrelia burgdorferi (Bb) antibody production in acute Lyme neuroborreliosis (LNB). We recruited consecutive adult patients with LNB diagnosis based on strict selection criteria. Serum and cerebrospinal fluid (CSFs) were obtained, and clinical examination was performed pre-treatment, and 13 days and 4 months post-treatment. Pre-treatment positive Bb antibody index (AI) was detected in 34 of 43 (79%). All nine pre-treatment Bb AI negative patients, and 26 of 34 pre-treatment Bb AI positive patients reported symptom duration <6 weeks. Eight patients, all Bb AI positive, reported symptom duration of 6 weeks or longer. Consequently, pre-treatment diagnostic sensitivity of Bb AI was 74% when symptom duration was <6 weeks, and 100% when 6 weeks or longer. Three patients converted from negative to positive Bb AI status post-treatment. The six patients who were persistently Bb AI negative had lower CSF cell count and protein at presentation, when compared with the patients with positive Bb AI. In conclusion, the diagnostic sensitivity of Bb AI is suboptimal in acute early LNB. Repeated post-treatment Bb AI testing, to confirm or reject LNB diagnosis, is unreliable, as the majority of initial Bb AI negative patients remained negative at follow-up.

Sensitivity and specificity of a commercial C6 peptide enzyme immuno assay in diagnosis of acute Lyme neuroborreliosis

The purpose of this study was to evaluate the diagnostic sensitivity and specificity of a commercial C6 enzyme immuno assay, QuickC6, in acute Lyme neuroborreliosis (LNB) in endemic areas. Paired sera and cerebral spinal fluids (CSFs) from 60 patients with definite LNB, eight patients with possible LNB, 18 patients with conditions mimicking LNB and 42 persons with noninfectious neurological disease were examined. The case definition of LNB was based on strict criteria during a prospective 4-month follow-up. The sensitivity of QuickC6 was 98% both in sera and CSFs, and the diagnostic specificity was 61% in sera and 88% in CSFs. QuickC6 is a sensitive, simple and cost-effective screening test in serum and CSF in diagnosis of acute LNB. Specificity needs further evaluation.

Isoelectric focusing is superior to immunofixation electrophoresis in diagnosing CNS inflammation

BACKGROUND

A sensitive method to detect intrathecal IgG production is important in diagnosing inflammatory central nervous system (CNS) diseases, including multiple sclerosis (MS).

OBJECTIVE

To compare cerebrospinal fluid (CSF) electrophoresis with isoelectric focusing (IEF), immunofixation-peroxidase electrophoresis (IFPE) and high-resolution agarose electrophoresis with protein-staining (HRAGE).

METHODS

Paired serum and CSF samples from 307 consecutive patients attending a general neurology clinic were examined with IEF, IFPE and HRAGE. Clinical diagnosis was based on review of the patients' medical records after an average of 4 years.

RESULTS

The sensitivity for detecting any inflammatory (autoimmune or infectious) CNS disease (52 patients) was 67% for IEF, 50% for IFPE and 29% for HRAGE. The sensitivity for detecting MS (14 patients) was 93%, 86% and 29% respectively. The sensitivity for detecting clinically isolated syndrome (eight patients) was 75%, 25% and 13% respectively. The number of oligoclonal bands in IEF was higher in inflammatory than in non-inflammatory neurological diseases or symptoms, but similar in MS and other inflammatory diseases.

CONCLUSION

IEF is the method of choice in diagnosing intrathecal IgG synthesis.

Chronic polyneuropathy and Lyme disease

Infection of the peripheral nervous system with Borrelia burgdorferi can present as a cranial neuropathy or radiculopathy with cerebrospinal fluid (CSF) pleocytosis and intrathecal antibody production against B. burgdorferi, or as an asymmetric peripheral neuropathy with acrodermatitis chronica atrophicans (ACA) and normal CSF findings. According to North American studies, it can also present as a symmetric chronic polyneuropathy without ACA or other Lyme manifestations. Our purpose was to investigate the prevalence of B. burgdorferi antibodies in patients presenting with isolated chronic polyneuropathy (PN) in a European region with high incidence of Lyme disease. Sera from 209 PN patients and 247 healthy blood donors from Vest-Agder County, Norway, were examined. Borrelia burgdorferi antibodies were detected in 43 (21%) PN patients and in 45 (18%) healthy blood donors (P = 0.553). The prevalence of B. burgdorferi antibodies was similar (P = 0.311) in cryptogenic PN (24/102, 24%) and PNs of identified etiologies (19/107, 18%). PN patients with B. burgdorferi antibodies had normal spinal fluid white cell count and they did not differ clinically or electrophysiologically from PN patients without antibodies. None of 20 antibody-positive PN patients responded to antimicrobial treatment. The study shows that, in Europe, chronic distal PN without ACA or other Lyme manifestations is very rarely caused by a B. burgdorferi infection.

Absence of focal neurological involvement in tick-borne relapsing fever in northern Tanzania

The aim of the study was to chart incidence and clinical features of tick-borne relapsing fever in Tanzania. Consecutive patients with fever and spirochetes demonstrated in a thick blood smear at Haydom Lutheran Hospital from 1 January to 31 December 2003 underwent clinical and cerebrospinal fluid (CSF) examination. Forty-four patients were included, making an estimated minimum annual incidence of 11 per 100 000 population in this region. The mortality rate was 2.3% (95% CI = 0-12). The most frequent complaints were generalized malaise (93%), headache (86%), nausea and vomiting (52%). None of the patients [0% (95% CI = 0-8)] had focal neurological symptoms. Cell count in CSF was normal in 22 and slightly elevated (6-12 leukocytes/mm(3)) in 20 patients. Two of three pregnancies had a poor outcome. Jarisch-Herxheimer reactions, bleeding complications and ocular manifestations were infrequent. In conclusion, tick-borne relapsing fever is a common disease in the Northern highland of Tanzania, but in contrast to other parts of the world, neurological involvement is uncommon in this area.

Onset and course of chronic inflammatory demyelinating polyneuropathy

Chronic inflammatory demyelinating polyneuropathy (CIDP) is clinically heterogeneous. Our purpose was to determine whether initial progression time, clinical features, and distribution of nerve conduction slowing at presentation correlate with clinical course and prognosis. We examined how findings at presentation related to clinical course during an average follow-up time of 4.0 (range 1.0-9.0) years in 44 patients with CIDP. We calculated terminal latency index (TLI), a measure of differential slowing in distal relative to more proximal nerve segments. Patients with acute or subacute onset (progression over less than 8 weeks) had a higher remission rate (P = 0.012) than patients with chronic onset (progression over more than 8 weeks). Patients with proximal weakness had a higher remission rate than patients with the distal phenotype (P < 0.001). All 5 patients with a relapsing course had subacute onset. They had lower TLIs, suggesting a more distal pattern of demyelination, than patients with a monophasic or chronic course. In conclusion, subacute onset and presence of proximal weakness are good prognostic signs that correlate with a high rate of recovery to normal in CIDP. Distal accentuation of conduction slowing at presentation correlates with subacute onset and a relapsing course.

Autoimmunity against the ryanodine receptor in myasthenia gravis

Some myasthenia gravis (MG) patients have antibodies against skeletal muscle antigens in addition to the acetylcholine receptor (AChR). A major antigen for these antibodies is the Ca2+ release channel of the sarcoplasmic reticulum the ryanodine receptor (RyR). These antibodies are found mainly in MG patients with a thymoma MG and correlate with severe MG symptoms. The antibodies recognize a region near the N-terminus on the RyR, which seems to be of importance for RyR regulation. The antibodies cause allosteric inhibition of RyR function in vitro, inhibiting Ca2+ release from sarcoplasmic reticulum.

Autoantibodies in thymoma-associated myasthenia gravis with myositis or neuromyotonia

BACKGROUND

About 50% of patients with thymoma have paraneoplastic myasthenia gravis (MG). Myositis and myocarditis or neuromyotonia (NMT) will also develop in some. Patients with thymoma-associated MG produce autoantibodies to a variety of neuromuscular antigens, particularly acetylcholine receptor (AChR), titin, skeletal muscle calcium release channel (ryanodine receptor [RyR]), and voltage-gated potassium channels (VGKC).

OBJECTIVE

To examine whether neuromuscular autoantibodies in patients with thymoma correlate with specific clinical syndromes.

METHODS

Serum and plasma samples from 19 patients with thymoma-associated MG, of whom 5 had myositis and 6 had NMT, underwent testing for antibodies to AChR, titin, RyR, and VGKC.

RESULTS

Antibodies to AChR and titin were found in 19 and 17 patients, respectively. Antibodies to RyR correlated with the presence of myositis (P = .03); they were found in all 5 patients with myositis and in only 1 patient with NMT, but also in 4 of 8 patients with neither disease. Antibodies to VGKC were found in 4 patients with NMT, 1 of 3 patients undergoing testing for myositis, and 2 of 7 patients undergoing testing with neither comorbidity. Presence of RyR antibodies correlated with high levels of titin antibodies.

CONCLUSIONS

The results appear to distinguish partially between 3 groups of patients with thymoma-associated MG: the first with RyR antibodies and myositis or myocarditis, the second with NMT without RyR antibodies, and the third without RyR antibodies, myositis, or NMT. Differences in the thymoma may underlie these pathologic associations.

Ryanodine receptor gene expression thymomas

Ryanodine receptor (RyR) antibodies are present in sera of myasthenics with thymoma, and their titer correlates with morbidity and mortality. We investigated whether skeletal muscle RyR expression in thymic tissues could be the source of immune sensitization to the RyR. Skeletal muscle RyR gene expression was investigated using reverse transcription followed by semiquantitative polymerase chain reaction. Hyperplastic and normal thymuses expressed significant levels of RyR, but RyR gene transcripts was statistically less likely in thymomas than in hyperplastic and normal thymus (P < 0.05). The presence of RyR transcripts in thymomas did not correlate with myasthenic manifestations, thymic pathology, or serum RyR antibodies. We conclude that the skeletal muscle RyR in thymoma is not the inciting antigen for immune sensitization to RyR epitopes in thymoma-associated myasthenia gravis.

Myasthenia gravis sera containing antiryanodine receptor antibodies inhibit binding of [3H]-ryanodine to sarcoplasmic reticulum

Myasthenia gravis (MG) patients with thymoma often have antibodies against the calcium-release channel of the sarcoplasmic reticulum (SR) in striated muscle, the ryanodine receptor (RyR). RyR function can be tested in vitro by measuring the degree of [3H]-ryanodine binding to SR. In this study, sera from 9 out of 14 MG patients containing RyR antibodies inhibited [3H]-ryanodine binding to SR membranes from rat skeletal muscle. The 9 patients with antibodies inhibiting ryanodine binding had more severe MG than those with noninhibiting antibodies (P = 0.006). Sera from MG patients with acetylcholine receptor and titin muscle antibodies but no antibodies against RyR and blood-donor sera did not have an inhibiting effect in the [3H]-ryanodine binding assay. The results show that RyR antibodies in MG patients have high affinity for the RyR, and that the binding of antibodies probably affects calcium release from SR by locking the RyR ion channel in a closed position.

[Neurologic paraneoplastic syndromes and anti-neuronal antibodies]

A neurologic paraneoplastic syndrome may be the first sign of an occult and treatable cancer. Some syndromes are associated with autoantibodies against neuronal antigens. Patients with cerebellar degeneration and ovarian or breast cancer have antibodies against 34 and 62 kilodalton (kDa) proteins in Purkinje cell cytoplasm: anti-Yo antibodies. Patients with encephalomyelitis or sensory neuronopathy and small cell lung cancer have antibodies against 35-40 kDa neuronal nuclear proteins: anti-Hu antibodies. Patients with opsoclonus-myoclonus and breast cancer have antibodies against 55 and 80 kDa neuronal nuclear proteins: anti-Ri antibodies. Patients with Lambert-Eaton myasthenic syndrome and small cell lung cancer have antibodies against voltage-gated calcium channels (anti-VGCC) in motor nerve terminals. The presence of anti-neuronal antibodies strongly indicates that a neurological syndrome is paraneoplastic, and often identify the site of an occult neoplasm. However, the absence of detectable antibodies does not rule out the presence of an underlying tumour.

Thymomas express epitopes shared by the ryanodine receptor

Myasthenia gravis (MG) patients with thymoma have antibodies against ryanodine receptor (RyR) of skeletal and heart muscle. In this study, thymomas were examined for reactivity with a panel of polyclonal rabbit antibodies against various short peptides of RyR. An antibody against peptide C2 in the transmembrane region of RyR stained thymoma epithelial cells in cryosections of 17/23 thymomas, and detected a 40-kDa peptide in Western blotting of a thymoma membrane fraction. The other RyR antibodies did not react with thymoma tissue. The anti-C2 RyR antibody did not react with normal thymus, tonsil or carcinoma of colon. The results strongly indicate that epithelial thymoma cells express an epitope shared by the transmembrane region of skeletal and cardiac muscle RyR.

Titin antibodies in patients with late onset myasthenia gravis: clinical correlations

We have tested sera from 21 thymectomized patients with onset of MG after 40 years of age and without thymoma for antibodies against titin, using ELISA with the titin peptide MGT-30. Titin is a myofibrillar protein unique to striated muscle and important for the elastic recoil of muscle cells. Titin antibodies were detected in 9 of the 21 sera. MG symptoms as assessed by a 6 point disability score (0-5) were significantly more severe in the titin antibody positive patients both at peak of illness; 3.7 vs. 3.1 (p < 0.02) and at latest follow up; 2.1 vs. 0.8 (p < 0.01). All titin antibody positive patients were on immunosuppressive drug treatment at least follow-up, whereas only 3 of 12 patients without titin antibodies used immunosuppressive drugs. The presence of circulating titin antibodies in late-onset non-thymoma MG patients indicates a more severe disease.

Ryanodine receptor antibodies related to severity of thymoma associated myasthenia gravis

Ryanodine receptor (RyR) antibodies are detected in about 50% of patients with myasthenia gravis who have a thymoma. The RyR is a calcium release channel involved in the mechanism of excitation-contraction coupling in striated muscle. In this study the severity of myasthenia gravis assessed by a five point disability score was compared between 12 patients with myasthenia gravis, a thymoma, and RyR antibodies and 10 patients with myasthenia gravis and a thymoma but without such antibodies. Symptoms of myasthenia gravis were significantly more severe in patients with RyR antibodies. The mean (SD) disability scores were 3.7(0.5) in patients with antibodies and 2.7 (0.9) in those without at peak of illness, (p = 0.01) and 3.4(1.4) v 1.6(0.7) at the end of an average observation period of five years (p = 0.002). The number of deaths due to myasthenia gravis was five of 12 RyR antibody positive patients, and none of 10 RyR antibody negative patients (p = 0.04). RyR antibody levels correlated positively with severity of myasthenia gravis. The presence of circulating RyR antibodies seems to be associated with a severe form of thymoma associated myasthenia gravis.

Anti-cardiac ryanodine receptor antibodies in thymoma-associated myasthenia gravis

Sera from myasthenia gravis (MG) patients with thymoma were examined in Western blot for the presence of antibodies to proteins in the sarcoplasmic reticulum (SR) of cardiac muscle. Fourteen of 30 MG thymoma sera had IgG antibodies to a protein with the same electrophoretic mobility as cardiac muscle ryanodine receptor (RyR). Anti-cardiac RyR antibodies were not detected in any of the 45 sera from MG patients without thymoma. The same 14 MG thymoma sera, but none of the others, bound to RyR from skeletal muscle as well. Neutralization experiments showed that the anti-RyR antibodies in MG patient cross-reacted with cardiac and skeletal muscle RyR. Since skeletal and cardiac muscle RyRs are antigenically different, our findings may indicate that autoantibodies to RyR in MG originate by sensitization to a peptide shared by cardiac and skeletal muscle RyR, rather than to the complete native RyR.

Titin antibodies in myasthenia gravis: identification of a major immunogenic region of titin

Approximately 15% of patients with myasthenia gravis (MG) have thymus neoplasia. These MG with thymoma (MGT) patients show autoantibodies to striated muscle as well as autoantibodies to acetylcholine receptor. To characterize these thymoma-associated muscle antigens, we cloned a number of immunopositive cDNAs by immunoscreening muscle cDNA libraries with sera from MGT patients. Analysis of the isolated cDNAs show that all share a common sequence encoding a distinct region of the titin gene. We expressed this main immunogenic region (MIR) of titin in Escherichia coli, and determined autoantibody serum titers directed against the obtained recombinant antigen in a variety of patients. We could detect titin MIR autoantibodies in 97% of sera from MGT patients but not in control sera from healthy blood donors. Therefore, expressed titin from the MIR of the molecule is a sensitive marker antigen for evaluating the presence of thymoma in MG.

IgG subclass distribution of ryanodine receptor autoantibodies in patients with myasthenia gravis and thymoma

Patients with myasthenia gravis (MG) and thymoma often have autoantibodies to the ryanodine receptor (RyR), a ligand-gated Ca(2+)-release channel in the sarcoplasmic reticulum of striated muscle. Using an ELISA, we studied the Ig isotype and IgG subclass distribution of RyR autoantibodies in sera from 30 MG patients with thymoma. RyR IgG antibodies were detected in 16/30 sera. 14/30 sera had IgG1 RyR antibodies, and 15/30 sera had IgG3 RyR antibodies. All sera with IgG1 RyR antibodies also contained IgG3 antibodies. A small number of sera had low amounts of IgG2, IgG4, IgA or IgM RyR antibodies. The RyR autoantibodies are therefore mainly expressed in the IgG1 and IgG3 subclasses. The RyR autoantibodies may be of pathogenic significance by interfering with the mechanism of excitation-contraction coupling in striated muscle.

Ryanodine receptor autoantibodies in myasthenia gravis patients with a thymoma

Sera from patients with myasthenia gravis were examined by Western blot for the presence of antibodies to proteins of the sarcoplasmic reticulum from rabbit skeletal muscle. Fourteen of 30 patients with myasthenia gravis and a thymoma had IgG autoantibodies to the calcium release channel of the sarcoplasmic reticulum (the ryanodine receptor), which plays a crucial role in the mechanism of excitation-contraction coupling in striated muscle. Ryanodine receptor autoantibodies were not detected in any of the 45 sera from patients with myasthenia gravis without a thymoma. Ryanodine receptor autoantibodies may have pathogenetic relevance in thymoma-associated myasthenia gravis.

Myasthenia gravis patients with a thymoma have antibodies against a high molecular weight protein in sarcoplasmic reticulum

Our purpose was to investigate whether components of the sarcoplasmic reticulum (SR) are relevant antigens in myasthenia gravis (MG). Using enzyme-linked immunosorbent assay (ELISA), 75 MG sera and 120 control sera were examined for IgG antibodies against SR prepared from rabbit skeletal muscle. 16/30 thymoma MG patients had IgG antibodies that reacted with SR. 1/30 MG patients with thymic hyperplasia and 3/15 MG patients with thymic atrophy had SR antibodies in low concentrations. Control sera were negative. Using immunoblot, SR antibodies were detected in the thymoma group only. 14/30 sera from thymoma patients reacted with a protein of 320 kDa relative molecular weight. The only reported SR protein with similar electrophoretic mobility is the subunit of the spanning protein which links junctional SR to sarcolemma and functions as a calcium-release channel.

Left ventricular function in myasthenia gravis

Myasthenia gravis is an autoimmune disorder with autoantibodies to acetylcholine receptors of skeletal muscle. Left ventricular diastolic function was studied with M-mode and Doppler echocardiography in 25 patients with myasthenia and in a group of age- and heart rate-matched control subjects. In the patients, diastolic peak filling rate was reduced by 37%, and Doppler peak early filling velocity (E) was reduced by 12% compared with the control subjects (2.7 +/- 0.7 vs 4.2 +/- 1.0 s-1, and 76 +/- 8 vs 85 +/- 15 cm/s, respectively; p less than 0.05). Peak atrial filling velocity (A) was increased by 38% (68 +/- 17 vs 48 +/- 9 cm/s; p less than 0.01), and consequently the E:A ratio in the group of patients was reduced by 33% (1.22 +/- 0.40 vs 1.81 +/- 0.33; p less than 0.001). End-diastolic dimension was 5.0 +/- 0.5 cm in both groups, heart rate was 70 +/- 12 vs 68 +/- 16 beats/min (p = not significant [NS]), M-mode ejection fraction was 76 +/- 8 vs 79 +/- 5% (p = NS), M-mode peak ejection rate was -1.9 +/- 0.4 vs -2.1 +/- 0.3 s-1 (p = NS), and peak aortic outflow velocity was 109 +/- 18 vs 98 +/- 13 cm/s (p = NS). Twenty-three patients and 15 control subjects were studied before and after intake of the acetylcholine-esterase inhibitor pyridostigmine.(ABSTRACT TRUNCATED AT 250 WORDS)

Heart muscle antibodies in myasthenia gravis

Myasthenia gravis (MG) may in some patients, especially in those with a thymoma, involve the heart. Using an ELISA, we measured heart muscle antibodies in sera from 75 MG patients and in 173 control sera. Heart muscle antibodies were detected in 29/30 thymoma MG patients, in none of 30 young onset MG patients with thymic hyperplasia and in 7/15 late onset MG patients with thymic atrophy. Among the controls, four sera had a very low concentration of heart muscle antibodies. Absorption studies showed that the heart muscle antibodies cross-react with skeletal muscle, but are unrelated to acetylcholine receptor antibodies.

[Heart disease in myasthenia gravis]

The symptoms in myasthenia gravis are mainly due to reduced function of skeletal muscle. But some patients, especially those with a thymoma, have symptoms or signs of myasthenia-related heart disease. Some of our patients with histological myocarditis have died suddenly and unexpectedly. The frequency of electrocardiographic abnormalities among myasthenic patients has increased. Patients with myasthenia gravis should be subjected to cardiac monitoring after thymic surgery and during myasthenic crisis and other severe illnesses. If clinical examination leads to suspicion of myocarditis, the patient should receive immunosuppressive therapy.