Proteolytic ectodomain shedding of muscle-specific tyrosine kinase in myasthenia gravis.

Autoantibodies to muscle-specific tyrosine kinase (MuSK) proteins at the neuromuscular junction (NMJ) cause refractory generalized myasthenia gravis (MG) with dyspnea more frequently than other MG subtypes. However, the mechanisms via which MuSK, a membrane protein locally expressed on the NMJ of skeletal muscle, is supplied to the immune system as an autoantigen remains unknown. Here, we identified MuSK in both mouse and human serum, with the amount of MuSK dramatically increasing in mice with motor nerve denervation and in MG model mice. Peptide analysis by liquid chromatography-tandem-mass spectrometry (LC-MS/MS) confirmed the presence of MuSK in both human and mouse serum. Furthermore, some patients with MG have significantly higher amounts of MuSK in serum than healthy controls. Our results indicated that the secretion of MuSK proteins from muscles into the bloodstream was induced by ectodomain shedding triggered by neuromuscular junction failure. The results may explain why MuSK-MG is refractory to treatments and causes rapid muscle atrophy in some patients due to the denervation associated with Ab-induced disruption of neuromuscular transmission at the NMJ. Such discoveries pave the way for new MG treatments, and MuSK may be used as a biomarker for other neuromuscular diseases in preclinical studies, clinical diagnostics, therapeutics, and drug discovery.

Bladder dysfunction as the initial presentation of multiple system atrophy: a prospective cohort study.

OBJECTIVES: Multiple system atrophy (MSA) is a disease that combines autonomic (orthostatic or bladder) with motor [parkinsonian (MSA-P) or cerebellar (MSA-C)] dysfunction. While bladder dysfunction may occur earlier than motor disorders, thus far no prospective study has been available to determine how often and how early bladder autonomic dysfunction predates motor dysfunction in MSA. Therefore, we present data from detailed history-taking in patients with MSA. METHODS: This is a prospective cohort study. Detailed history-taking was performed and a questionnaire administered in 121 MSA patients (73 MSA-C, 48 MSA-P; 74 men, 47 women; age, 58 ± 8.0 years; initial recruitment period, 5 years; follow-up, 6.5 ± 4.0 years). RESULTS: Among the patients with MSA-C, 40 patients (55%) suffered motor dysfunction first, 22 (30%) suffered autonomic dysfunction first, and 11 (15%) initially suffered both simultaneously. Among the patients with MSA-P, 22 patients (46%) suffered motor dysfunction first, 22 (46%) suffered autonomic dysfunction first, and two (8%) initially suffered both simultaneously. Among the 'autonomic-first' subgroup of MSA-C patients, five suffered orthostatic dysfunction first, 13 suffered urinary dysfunction first, and four initially suffered both simultaneously. Among the 'autonomic-first' subgroup of MSA-P patients, six suffered orthostatic dysfunction first, nine suffered urinary dysfunction first, and seven initially suffered both simultaneously. Urinary symptoms were further preceded by erectile dysfunction in men. Overall, 18.2% of patients suffered only urinary symptoms initially, and the mean interval from the onset of urinary to the onset of motor symptoms was 2.8 years (range 1-7 years). CONCLUSION: In MSA patients, 18.2% presented with bladder dysfunction as the sole initial manifestation, and the mean interval from the onset of urinary to the onset of motor symptoms was 2.8 years. It is clinically important to avoid unnecessary prostatic surgery when MSA patients see urologists before neurologists.

Immunization of mice with LRP4 induces myasthenia similar to MuSK-associated myasthenia gravis.

Since the first report of experimental animal models of myasthenia gravis (MG) with autoantibodies against low-density lipoprotein receptor-related protein 4 (LRP4), there have not been any major reports replicating the pathogenicity of anti-LRP4 antibodies (Abs). Recent clinical studies have cast doubt on the specificity and pathogenicity of anti-LRP4 antibodies for MG, highlighting the need for further research. In this study, we purified antigens corresponding to the extracellular region of human LRP4 stably expressed with chaperones in 293 cells and used these antigens to immunize female A/J mice. Immunization with LRP4 protein caused mice to develop myasthenia having similar electrophysiological and histological features as are observed in MG patients with circulating Abs against muscle-specific kinase (MuSK). Our results clearly demonstrate that active immunization of mice with LRP4 proteins causes myasthenia similar to the MG induced by anti-MuSK Abs. Further experimental and clinical studies are required to prove the pathogenicity of anti-LRP4 Abs in MG patients.

Bladder recovery relates with increased mid-cingulate perfusion after shunt surgery in idiopathic normal-pressure hydrocephalus: a single-photon emission tomography study.

AIMS OF STUDY: It is reported that severe bladder disorder in idiopathic normal-pressure hydrocephalus (iNPH) is predicted by right frontal hypoperfusion. However, it is not known whether bladder recovery is predicted by brain perfusion change after shunt surgery. To address this issue, we compared bladder and brain function before and after shunt surgery in iNPH. METHODS: We enrolled 75 patients in the study. Before and 12 months after shunt surgery, we analyzed brain perfusion by SPECT and bladder disorder by a specialized grading scale. The scale consisted of grade 0, none; grade 1, urinary urgency and frequency; grade 2, urinary incontinence 1-3 times a week; grade 3, urinary incontinence >daily; and grade 4, loss of bladder control. More than one grade improvement is defined as improvement, and more than one grade decrement as worsening; otherwise no changes. RESULTS: Comparing before and after surgery, in the bladder-no-change group (32 cases) there was an increase in blood flow which is regarded as reversal of enlargement in the Sylvian fissure and lateral ventricles (served as control). In contrast, in the bladder-improved group (32 cases) there was an increase in bilateral mid-cingulate, parietal, and left frontal blood flow (p < 0.05). In the bladder-worsened group (11 cases) no significant blood flow change was observed. CONCLUSION: The present study showed that after shunt surgery, bladder recovery is related with mid-cingulate perfusion increase in patients with iNPH. The underlying mechanism might be functional restoration of the mid-cingulate that normally inhibits the micturition reflex.

Lower urinary tract function in dementia with Lewy bodies (DLB).

OBJECTIVES: Dementia with Lewy bodies (DLB) is the second most common degenerative cause of dementia, whereas lower urinary tract (LUT) function in DLB patients has not been fully delineated. We investigated LUT function in DLB by clinical-urodynamic observations. METHODS: We examined 32 patients with DLB (23 men, 9 women; aged 59-86 [mean, 75.9] years; disease duration, 0.2-17 [3.3] years). All patients underwent an electromyography-cystometry, and 21 patients underwent the sphincter motor unit potential analysis. RESULTS: Ninety-one percent of patients had LUT symptoms: nighttime frequency (>8 times), 84%, and urinary incontinence (>1 per week), 50%. Detrusor overactivity was revealed in 87.1%, whereas postvoid residual was minimal. Neurogenic changes were shown in 50%. CONCLUSION: LUT dysfunction is a common feature in DLB, attributable not only to dementia and immobility, but also to central and peripheral types of somato-autonomic dysfunction.

Constipation triggered the malignant syndrome in Parkinson's disease.

A 69-year-old, chronically constipated patient with Parkinson's disease developed fecal impaction and the malignant syndrome simultaneously, even while the patient was taking anti-parkinsonian drugs as prescribed. Administration of intravenous levodopa and oral Dai-kenchu-tou, an herbal medicine with serotonergic 5-HT3 receptor agonistic property successfully ameliorated his clinical symptoms. Constipation may trigger worsening of Parkinson's disease and occurrence of the malignant syndrome by affecting levodopa absorption. Further, improved bowel motility may prevent worsening of Parkinson's disease and occurrence of the malignant syndrome.

Crohn's disease and stroke in a young adult.

A 36-year-old man with a 21-year history of Crohn's disease suddenly developed left hemiparesis. He did not have atherosclerotic risk factors on admission, but he had marked dehydration which was likely due to prolonged home intravenous hyper-alimentation. Brain MRI revealed lacunar infarction in the right anterior corona radiata. An anticoagulation drug and a free-oxide scavenger successfully reversed his neurological deficits almost completely. Stroke in young adults less than 40 years old is extremely rare; therefore, we conclude that Crohn's disease can be a risk factor for acute ischemic stroke in our case, due most probably to dehydration and other complex mechanisms.

VGCC antibody-positive paraneoplastic cerebellar degeneration presenting with positioning vertigo.

A 70-year-old woman developed paraneoplastic cerebellar degeneration (PCD) due to P/Q-type and N-type voltage-gated calcium channel antibodies and small cell lung cancer, the main clinical manifestations of which were severe positioning vertigo and vomiting. Loss of the visual suppression of caloric nystagmus, spontaneous downbeat nystagmus, periodic alternating nystagmus, and positioning vertigo in our patient most probably corresponds to the cerebellar flocculus/paraflocculus lesion caused by PCD.

Hashimoto's ophthalmopathy.

The authors reported 2 cases of Hashimoto's ophthalmopathy. These cases presented with no preceding illness; euthyroid state; acute presentation of painful or painless ophthalmoplegia, preferentially affecting the lateral rectus muscles; positive antithyroglobulin/antithyroid peroxidase antibodies and good responses to steroid treatment. Awareness of this atypical form of ophthalmopathy is important, as glucocorticoid treatment results in a significant improvement of this disorder.

Pathogenesis of reduced or increased bladder sensation.

OBJECTIVE: Pathogenesis of reduced or increased bladder sensation is not well known. Hence, we systematically investigated the frequency of reduced or increased bladder sensation in neurologic/mental diseases. METHODS: We analyzed 911 patients who were referred from within our hospital. Data registries included a diagnosis, a lower urinary tract symptom questionnaire, a urodynamic study, and neurological examinations. Reduced bladder sensation is defined as bladder volume at the first sensation >300 ml. Increased bladder sensation is defined as bladder volume at the first sensation <100 ml. These patients were stratified into those with and without DO. RESULTS: Neuropathies are the most common cause of reduced bladder sensation (33.3-43.8% in diabetic neuropathy, etc.). Myelopathies are the second most common cause (17.4-25.0% in multiple sclerosis, etc.). Less common is brain diseases (9.6% in multiple system atrophy, etc.). In contrast, myelopathies are the most common cause of increased bladder sensation without DO (25.0-40.0% in spinal forms of systemic lupus erythematosus, Sjogren's syndrome, etc.). Neuropathies are the second most common (17.3-22.2% in post-pelvic organ surgery, diabetic neuropathy, etc.). Less common is brain/mental diseases (20.0% in psychogenic bladder dysfunction, 8.1% in Parkinson's disease, etc.). CONCLUSION: The present study revealed that neuropathies are the most common cause of reduced bladder sensation in neurologic/mental diseases. Increased bladder sensation without DO occurs mainly in peripheral and central sensory pathway lesions, as well as in basal ganglia lesions and psychogenic bladder dysfunction. Reduced and increased bladder sensation should be a major treatment target for maximizing patients' quality of life.

Prevalence and mechanism of bladder dysfunction in Guillain-Barré Syndrome.

AIM: To examine the prevalence and mechanism of urinary dysfunction in GBS. METHODS: Urinary symptoms were observed and neurological examinations made repeatedly during hospitalization of 65 consecutive patients with clinico-neurophysiologically definite GBS. The patients included 41 men, 24 women; mean age, 41 years old; mean Hughes motor grade, 3; AIDP, 28, AMAN, 37. Urodynamic studies consisted of uroflowmetry, measurement of post-micturition residuals, medium-fill water cystometry, and external anal sphincter electromyography. RESULTS: Urinary dysfunction was observed in 27.7% of GBS cases (urinary retention, 9.2%). Urinary dysfunction was related to the Hughes motor grade (P < 0.05), defecatory dysfunction (P < 0.05), age (P < 0.05), and negatively related to serum IgG class anti-ganglioside antibody GalNAc-GD1a (P < 0.05). Urinary dysfunction was more common in AIDP (39%) than in AMAN (19%). No association was found between antibody titer against neuronal nicotinic acetylcholine receptors and urinary dysfunction. Urodynamic studies in nine patients, mostly performed within 8 weeks after disease onset, revealed post-void residual in 3 (mean 195 ml), among those who were able to urinate; decreased bladder sensation in 1; detrusor overactivity in 8; low compliance in 1; underactive detrusor in 7 (both overactive and underactive detrusor in 5); and nonrelaxing sphincter in 2. CONCLUSION: In our series of GBS cases, 27.7% of the patients had urinary dysfunction, including urinary retention in 9.2%. Underactive detrusor, overactive detrusor, and to a lesser extent, hyperactive sphincter are the major urodynamic abnormalities. The underlying mechanisms of urinary dysfunction appear to involve both hypo- and hyperactive lumbosacral nerves. Neurourol. Urodynam. 28:432-437, 2009. (c) 2009 Wiley-Liss, Inc.

[An improved case of bedridden mental impairment with normal pressure hydrocephalus associated with acoustic neurinoma after tumor resection].

A 67-year-old woman developed gait disturbance, dysarthria, cognitive impairment and incontinence at age 65, and became bedridden. She showed mutism, stupor and lower limb spasticity. Cranial CT and MRI revealed marked ventricular enlargement and a cerebellopontine angle tumor. CSF study showed normal pressure (125 mmH2O) and elevated protein (143 mg/dl). Radionuclide cisternography showed redistribution of radionuclide to the ventricles and intraventricular residual radionuclide after 72 hours, which allowed a diagnosis of normal pressure hydrocephalus. After removal of the tumor, ventricle size and CSF protein decreased, and the symptoms of cognitive impairment and motor dysfunction resolved. Histological examination showed acoustic neurinoma. Over the half of hydrocephalus following acoustic neurinoma shows a tendency to improve by surgical resection of the tumor. Neurologists who see cognitively impaired spastic bedridden patients should not overlook this pathology.

Myasthenia gravis with concomitant severe paraspinal muscle degeneration and mitochondrial DNA4977 deletion.

Recent reports have discussed the many causes of dropped head syndrome and bent spine syndrome. We described a case of myasthenia gravis with concomitant severe degeneration of spinal muscle, mitochondrial DNA4977 deletion and sensorineural deafness. These associations were thought to be independent, however this is an important case to consider the etiology of bent spine syndrome.