Fatigue in myasthenia gravis: is it more than muscular weakness?

Background

Few studies have focused on fatigue in myasthenia gravis (MG), and fatigue in relation to the autonomic system has never been systematically explored in these patients. The study aimed to document the prevalence of MG-related fatigue in ethnic Norwegians and to examine whether MG severity is associated with symptoms of autonomic disturbance, which in turn is associated with fatigue and functional disability.

Methods

Eighty two of the 97 who fulfilled the study inclusion criteria participated in the study. Controls were 410 age- and sex-matched subjects drawn from a normative sample (n = 2136) representative of the Norwegian population. Bivariate analyses and multivariate linear regression analyses were used to assess associations between questionnaire-reported MG severity, symptoms of autonomic disturbance, fatigue (mental and physical) and functional disability.

Results

Forty-four per cent (36/82) of patients fulfilled the criteria for fatigue compared with 22% (90/410) of controls (odds ratio 2.0; p = 0.003). Twenty-one per cent of patients (17/82) met the criteria for chronic fatigue versus 12% (48/410) of controls (odds ratio 1.96; p = 0.03). MG patients had higher total fatigue scores than controls (p < 0.001) and a high prevalence of autonomic symptoms, especially poor thermoregulation and sleep disturbance. According to multivariate analyses controlled for MG score, symptoms of autonomic disturbances were independently positively associated with fatigue (p < 0.001), and fatigue was independently negatively associated with functional level (p < 0.001).

Conclusion

Norwegian ethnic patients with MG have higher levels of fatigue and a higher prevalence of chronic fatigue than controls, even in patients in full remission. MG severity is highly suggestive to be associated with symptoms of autonomic disturbance, which in turn is associated with fatigue and the level of functional disability.

[Drugs that may trigger or exacerbate myasthenia gravis]

Myasthenia gravis (MG) is an autoimmune disease causing muscle weakness due to impaired transmission at the neuromuscular junction. MG or a MG-like condition may be triggered or exacerbated by several drugs used for treatment of other diseases. Drugs may interfere with the neuromuscular transmission through several mechanisms, either by affecting pre- or postsynaptic ion channels or by affecting acetylcholinesterase. Based on a literature search in PubMed and the authors' own clinical experiences, we provide an overview focusing on the most frequently used drugs that may exacerbate weakness in patients with MG. In our experience, symptomatic MG-patients who have a generalised disease are especially vulnerable to drug-induced exacerbations, while stable MG patients with few symptoms more seldom are. Nevertheless, patients with MG must receive treatment for co-existing conditions. It is important to be aware of a possible increase in muscle weakness when introducing a new drug. If the patient deteriorates, the new treatment must be withdrawn or the dose reduced.

Is the brain water channel aquaporin-4 a pathogenetic factor in idiopathic intracranial hypertension? Results from a combined clinical and genetic study in a Norwegian cohort

PURPOSE

Idiopathic intracranial hypertension (IIH) is a condition of increased intracranial pressure of unknown aetiology. Patients with IIH usually suffer from headache and visual disturbances. High intracranial pressure despite normal ventricle size and negative MRI indicate perturbed water flux across cellular membranes, which is provided by the brain water channel aquaporin-4 (AQP4). IIH could be associated with malfunctioning intracerebral water homeostasis and cerebrospinal fluid (CSF) reabsorption based on functional or regulatory alterations of AQP4.

METHODS

Clinical data, blood and CSF samples were collected from 28 patients with IIH. Clinical characteristics were assessed, and a genetic association study was performed by sequencing the AQP4 gene on chromosome 18. Genetic data were compared with 52 healthy controls and matched by age, sex and ethnicity. Chi-square test and linear discriminant analysis (LDA) were used in the search of a genotype-phenotype association.

RESULTS

While the majority of patients responded to medical treatment, four required shunt application. All, except one, had a good visual outcome. The 24 AQP4 gene SNPs showed no association with IIH. Full cross-validation of the LDA modelling resulted in only 55.1% correct classification of the cases and controls, with a corresponding estimated p-value 0.37.

CONCLUSIONS

Our genetic case-control study did not indicate an association between AQP4 gene variants and IIH. However, the theory of an etiopathogenic link between IIH and AQP4 is tempting, and discussed in this article. Association studies with large sample size are difficult to perform owing is the rarity of the condition.

An unusual case of the syndrome of cervical rib with subclavian artery thrombosis and cerebellar and cerebral infarctions

Background

Cerebellar and cerebral infarctions caused by the syndrome of cervical rib with thrombosis of subclavian artery are very unusual.

Case presentation

We report the case of a 49-year-old male patient with a right cervical rib compression leading to subclavian arterial thrombosis and both cerebellar and cerebral infarctions secondary to retrograde thromboembolisation. Follow-up imaging revealed partial resolution of the thrombosis after combined anti-coagulant and anti-platelet therapy. The cervical rib and first costa were surgically removed to prevent additional events.

Conclusion

Cervical rib vascular compression should be promptly diagnosed and treated in order to avoid further complications, including cerebrovascular ischemic events.

Late onset myasthenia gravis is associated with HLA DRB1*15:01 in the Norwegian population

Background

Acquired myasthenia gravis (MG) is a rare antibody-mediated autoimmune disease caused by impaired neuromuscular transmission, leading to abnormal muscle fatigability. The aetiology is complex, including genetic risk factors of the human leukocyte antigen (HLA) complex and unknown environmental factors. Although associations between the HLA complex and MG are well established, not all involved components of the HLA predisposition to this heterogeneous disease have been revealed. Well-powered and comprehensive HLA analyses of subgroups in MG are warranted, especially in late onset MG.

Methodology/Principal Findings

This case-control association study is of a large population-based Norwegian cohort of 369 MG patients and 651 healthy controls. We performed comprehensive genotyping of four classical HLA loci (HLA-A, -B, -C and -DRB1) and showed that the DRB1*15:01 allele conferred the strongest risk in late onset MG (LOMG; onset ≥60years) (OR 2.38, p_c7.4×10⁻⁵). DRB1*13:01 was found to be a protective allele for both early onset MG (EOMG) and LOMG (OR 0.31, p_c 4.71×10⁻⁴), a finding not previously described. No significant association was found to the DRB1*07:01 allele (p_nc = 0.18) in a subset of nonthymomatous anti-titin antibody positive LOMG as reported by others. HLA-B*08 was mapped to give the strongest contribution to EOMG, supporting previous studies.

Conclusion

The results from this study provide important new information concerning the susceptibility of HLA alleles in Caucasian MG, with highlights on DRB1*15:01 as being a major risk allele in LOMG.

Good long-term efficacy of pallidal stimulation in cervical dystonia: a prospective, observer-blinded study

BACKGROUND AND PURPOSE

Deep brain stimulation of the internal globus pallidus (GPi-DBS) is established as an effective treatment of primary generalised dystonia in controlled studies. In cervical dystonia (CD), only one previous study has reported observer-blinded outcome assessment of long-term GPi-DBS, with 1-year follow-up.

METHODS

In this prospective, single-centre study, eight patients with CD (7 women:1 man, 4 focal:4 segmental) treated with bilateral GPi-DBS for median (range) 30 (12-48) months, were evaluated by the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS; Severity, Disability and Pain scores), the Short-Form Health Survey-36 (SF-36), and the Becks Depression Index in an open design. In addition, a blinded rater assessed the TWSTRS Severity score from videos obtained preoperatively and at the last follow-up.

RESULTS

In the blinded evaluation, median (range) TWSTRS Severity score improved from 25 (19-30) to 8 (4-23) (P = 0.028), thus a 70% (23-82) score reduction. In the open evaluation, median Severity score improvement at the last follow-up was 73%, representing a significant further improvement from 50% at 6 months. The Disability and Pain scores improved by median 91% and 92%, respectively, and the SF-36 subdomain scores improved significantly. A reversible right hemiparesis and aphasia occured in one patient 4 days postoperatively, because of reversible oedema around the left electrode. No other serious adverse effects and no permanent morbidity were observed.

CONCLUSIONS

This single-blinded study shows good long-term efficacy of GPi-DBS in CD patients and supports using this treatment in those who have insufficient response to medical treatment.

Static and pulsatile intracranial pressure in idiopathic intracranial hypertension

OBJECTIVE

The aim of this observational study was to characterize the static and pulsatile intracranial pressure (ICP) in conservatively (medically) treated idiopathic intracranial hypertension (IIH) patients in need of shunt surgery, and also in patients with chronic daily headache (CDH) without visual disturbances.

METHODS

The material includes 14 IIH patients and 7 CDH patients in whom ICP was monitored continuously over-night. Static ICP was characterized by mean ICP, pulsatile ICP was characterized by the wave amplitude, rise time, and rise time coefficient.

RESULTS

In the IIH group all 14 had headache and visual disturbances. Mean ICP was high (> 15 mmHg) in only 7 patients (50%), while mean ICP wave amplitude was high (≥ 4 mmHg) in all 14 (100%). All IIH patients were shunted and improved clinically thereafter (i.e., relief from visual disturbances and/or headache). None in the CDH group had high mean ICP or mean ICP wave amplitude, and none were shunted.

CONCLUSIONS

In this cohort of 14 conservatively treated IIH patients with lasting and shunt-responsive headache and visual disturbances, the mean ICP wave amplitude was elevated (≥ 4 mmHg) in all patients despite normal mean ICP (< 15 mmHg) in 7 patients (all but one on medication). Therefore, the pulsatile ICP may be more relevant than the static ICP in the diagnostic setting for patients with IIH. Further prospective standardized approaches are warranted.

Airway limitation and exercise intolerance in well-regulated myasthenia gravis patients

OBJECTIVES

Myasthenia gravis (MG) is an autoimmune disease of neuromuscular synapses, characterized by muscular weakness and reduced endurance. Remission can be obtained in many patients. However, some of these patients complain of fatigue. The aim of this study was to assess exercise capacity and lung function in well-regulated MG patients.

PATIENTS AND METHODS

Ten otherwise healthy MG patients and 10 matched controls underwent dynamic spirometry, and a ramped symptom-limited bicycle exercise test. Spirometric variables included forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), and maximum voluntary ventilation (MVV). Exercise variables included maximal oxygen uptake (VO(2) max), anaerobic threshold (VO(2) AT) maximum work load (W), maximum ventilation (VE max), and limiting symptom.

RESULTS

Myasthenia gravis patients had significantly lower FEV1/FVC ratio than controls. This was more marked in patients on acetylcholine esterase inhibitors. On the contrary, patients not using acetylcholine esterase inhibitors had a significantly lower exercise endurance time.

CONCLUSION

Well-regulated MG patients, especially those using pyridostigmine, tend to have an airway obstruction. The modest airway limitation might be a contributing factor to their fatigue. Patients who are not using acetylcholinesterase inhibitor seem to have diminished exercise endurance in spite of their clinically complete remission.

[Neurofibromatosis type 2 and auditory brainstem implantation]

BACKGROUND

Neurofibromatosis type 2 (NF2) is a rare and severe autosomal dominant disorder caused by mutations in a tumour suppressor gene. This article reviews NF2 and its treatment with auditory brainstem implantation.

MATERIAL AND METHODS

The review is based on the authors' experience with the disease and literature identified through a non-systematic search of PubMed.

RESULTS

NF2 is caused by loss-of-normal function of the tumour suppressor protein merlin. Merlin normally suppresses cell growth and proliferation. The clinical picture is dominated by neurological symptoms, caused by multiple tumours - mainly schwannomas and meningeomas. The hallmark of the disease is development of bilateral vestibular schwannomas, and the most common presenting symptom in adults is progressive hearing loss. Presenile cataract, ocular motility disorders, peripheral neuropathy and skin tumours are other common findings. The majority of patients become deaf, many patients become severely disabled and life expectancy is reduced. The goal of management is conservation of function and maintenance of quality of life. Auditory brainstem implants stimulate the cochlear nucleus directly and provide substantial auditory benefits to patients with NF2.

INTERPRETATION

A multidisciplinary approach in specialty centres is recommended. Management by an experienced team reduces mortality and improves outcome after surgery. Auditory brainstem implantation is an important part of the hearing rehabilitation in these patients. Emerging knowledge of the molecular disease mechanisms offers hope for new therapeutic strategies.

A subhyaloid haemorrhage as the presenting symptom of bilateral optic neuropathy

A 28 year-old man with a spontaneous vitreous haemorrhage as the first sign of Leber's optic atrophy is presented. The blood collected in a central retrohyaloid area covering the left macula. The exact starting point of the haemorrhage was never positively identified, but it seemed to originate from an area of microangiopathy adjacent to the optic disc. For 8-10 months the vision of the left eye gradually decreased to counting fingers. A year later the visual acuity dropped to the same level on the right eye. The picture was compatible with Leber's optic atrophy. Other disorders causing bilateral optic neuropathy were excluded. A careful family history revealed several cases of visual problems for several generations. Vitreous haemorrhage as the first sign of Leber's optic atrophy has not previously been reported. Peripapillar microangiopathy, however, has been described in the asymptomatic stage of the disease.

[Primary and secondary dystonias]

BACKGROUND

Dystonia is a neurological syndrome, characterized by involuntary muscle contractions causing twisting, repetitive movements and abnormal postures. The aim of this brief review is to summarize the current state of knowledge as to the clinical, genetic, diagnostic and therapeutic aspects of dystonia.

MATERIAL AND METHODS

This article is based on own research, clinical experience and recent medical literature found by searching Medline.

RESULTS AND INTERPRETATIONS

Dystonia is the third most prevalent movement disorder in humans and is a common term for a group of primary (idiopathic) and secondary (symptomatic) movement disorders. For the primary types, tremor and myoclonus are the only symptoms in addition to the dystonia itself. Some primary dystonias have a hereditary component. Secondary dystonias are associated with other diseases with hereditary, metabolic, traumatic or exogen causes. There is still no curative treatment of dystonia, but new therapeutic methods increase the possibility of reducing involuntary movement, abnormal postures and pain, as well as improving function and quality of life for patients with dystonia.

Periodic abducens nerve palsy in adults caused by neurovascular compression

Unilateral abducens nerve palsy with periodic recurrences is a well-recognised finding in children, but is rare in adults. The underlying pathophysiological mechanism is unknown. Vascular compression of the nerve is suspected but never demonstrated. We describe an adult patient with, altogether, 11 periods of unilateral right-sided abducens palsy and arterial contact at the root exit zone of the symptomatic side.

Determinants and status of quality of life after long-term botulinum toxin therapy for cervical dystonia

The aim of this study was to assess health-related quality of life (HRQoL), using the Short Form Health Survey-36 (SF-36), in 70 cervical dystonia (CD) patients after long-term botulinum toxin (BTX) treatment (median 5.5 years), and to identify factors determining reduced HRQoL. We used combined patient-and physician-based measures to assess both CD severity [Toronto Western Spasmodic Torticollis Rating Scale, (TWSTRS)] and effect of long-term BTX treatment, and the Hospital Anxiety and Depression Scale (HAD) and General Health Questionnaire-30 to assess psychological distress. Mean SF-36 domain scores of the CD patients were reduced by <1 SD compared with age- and gender-matched population samples. High TWSTRS total scores and high HAD-depression (HAD-D) scores were the main factors associated with reduced scores in the physical and mental SF-36 domains, respectively. Patients evaluated to have a 'good effect' of long-term BTX treatment (n = 47), had significantly lower median TWSTRS total score, and a 3x lower frequency of high HAD-D scores, than those evaluated to an 'unsatisfactory effect' (n = 23). In conclusion, most CD patients enjoy a good HRQoL after long-term BTX therapy. Reduced HRQoL was associated with more severe disease and/or depressive symptoms.

[A 64-year old man with cognitive impairment and gait disturbance]

Intravascular lymphomatosis is a rare disease, characterized by occlusion of small arterioles and veins by malignant lymphoma cells. It often affects the central and peripheral nervous system and the skin. This case report illustrates the diagnostic challenge. Most patients develop rapidly progressive dementia combined with focal neurological symptoms. No relevant clinical, radiological or laboratory tests are available to diagnose the disease. Blood samples and bone marrow are usually normal. Diagnosis is often delayed and made post mortem. Brain biopsy could be diagnostic. The prognosis is poor, but early aggressive chemotherapy can potentially prolong the life span and in a few cases be curative. Intravascular lymphomatosis should be considered in patients with a combination of rapidly developing encephalopathy and focal neurological signs.

Microvascular decompression for hemifacial spasm: postoperative neurologic follow-up and evaluation of life quality

Microvascular decompression (MVD) is an effective and safe treatment in hemifacial spasm (HFS). Postoperative evaluations are usually made by neurosurgeons. Follow-up studies performed by neurologists and postoperative quality of life (QoL) investigations are lacking. All 25 HFS patients operated with MVD in our centre between 2000 and 2004 were evaluated with the recently validated HFS-7 scheme, extended with the item 'sleep disturbance due to HFS' (HFS-8). The patients underwent a careful neurological examination median 3 years after the operation. The evaluation focused on clinical aspects, changes in blood pressure and time until observable effect of MVD. The evaluation of HFS-7 questionnaire and the extended form (HFS-8) showed significant improvement in QoL after MVD. Neurological outcome was in almost all cases excellent or good. Eleven (44%) patients had no neurological deficits at all. Only one patient had serious complications with ipsilateral facial palsy, deafness, balance problems and vertigo. The other patients had minor neurological findings or symptoms. Eighteen (72%) patients experienced early effect within 3 months after MVD; seven (28%) patients had late effect between 6 and 14 months. Median age of the patients with late effect (62.6 years) was significantly higher than in those with early effect (52.7 years).