[Electrophysiological evidence of impaired neuromuscular junction in a case of phosphoglucomutase 1 deficiency manifesting fluctuating muscle weakness]

A 27 year-old Canadian man suffered from fluctuating muscle weakness in the past several years. The patient had a past history of intestinal bleeding, bifid uvula and hypothyroidism in his childhood. Repetitive nerve stimulation tests showed a decrement pattern in the left deltoid muscle. The single fiber electromyography of the left extensor digitorum muscle showed an increment of jitter. Both findings were improved by the edrophonium test. He was diagnosed as having phosphoglucomutase 1 (PGM1) deficiency, as the compound heterozygote mutation of the PGM1 gene was recognized in the whole-exome sequencing and the enzyme activity of PGM1 was defective in the biopsied muscle. Treatment with the galactose lead to improvement of the fluctuating muscle weakness and decremental pattern in the repetitive stimulation test. PGM1 deficiency should be listed in the differential diagnosis of the neuromuscular junction disorder, when the patient is seronegative for antibodies related with myasthenia gravis and shows symptoms or signs consistent with PGM1 deficiency.

A single-fibre EMG Study of Neuromuscular Transmission in Migraine Patients

It is known that mutations of CACNA1A, which encodes a neuronal P/Q Ca2+ channel, are present in patients with familial hemiplegic migraine, and possibly in other types of migraine as well. This calcium channel is also involved in neuromuscular transmission. To assess if the single-fibre EMG (SFEMG) method can demonstrate a neuromuscular transmission deficit in migraine, a group of 26 patients with different types of migraine and 20 healthy control subjects were studied. The migraine patients were divided into three groups: 8 patients with migraine without aura (MoA), 12 with migraine with aura excluding visual aura (MA) and 6 with visual aura (VA). A SFEMG of the voluntarily activated extensor digitorum communis muscle was performed. The SFEMG results were normal in the healthy controls and the MoA group (migraine without aura). Slight neuromuscular transmission disturbances were present in 6/12 (50%) of patients with MA and in 1/6 (17%) of patients with VA. We suggest that abnormal neuromuscular transmission detectable by SFEMG may reflect a genetically determined dysfunction of the P/Q Ca2+ channels in a subgroup of migraineurs with aura.

Patients with neuromuscular disorder

This article describes the preoperative preparation of patients with neuromuscular disorders. These entities are a relatively rare and diverse group of diseases that can affect various organ systems in addition to the central nervous system. The anesthetic implications for the various comorbidities are varied and can be profound. These patients should be optimized before surgery, with the involvement of a multidisciplinary team of specialists.

Neuromuscular junction in health and disease

A number of illnesses and other factors can affect the function of the neuromuscular junction (NMJ). These may have an affect at pre- or post-junctional sites. This review outlines the anatomy and the physiology of the NMJ. It also describes the mechanisms and physiological basis of many of the disorders of the NMJ. Finally, the importance of these disorders in anaesthetic practice is discussed.

The Predisposition to Inspiratory Upper Airway Collapse during Partial Neuromuscular Blockade

RATIONALE

Partial neuromuscular transmission failure by acetylcholine receptor blockade (neuromuscular blockade) or antibody-mediated functional loss (myasthenia gravis), even with a magnitude of muscle weakness that does not evoke respiratory symptoms, can evoke dysphagia and decreased inspiratory airflow, and increases the risk of susceptible patients to develop severe pulmonary complications.

OBJECTIVES

To assess whether impaired neuromuscular transmission predisposes individuals to inspiratory upper airway collapse, we assessed supraglottic airway diameter and volume by respiratory-gated magnetic resonance imaging, upper airway dilator muscle function (genioglossus force and EMG), and changes in lung volume, respiratory timing, and peripheral muscle function before, during, and after partial neuromuscular blockade in healthy, awake volunteers.

MEASUREMENTS AND MAIN RESULTS

Partial neuromuscular blockade (train-of-four [TOF] ratio: 0.5 and 0.8) was associated with the following: (1) a decrease of inspiratory retropalatal and retroglossal upper airway volume to 66 +/- 22 and 82 +/- 12% of baseline, which was significantly more intense in the retropalatal area; (2) an attenuation of the normal increase in anteroposterior upper airway diameter during forced inspiration to 74 +/- 18% of baseline; (3) a decrease in genioglossus activity during maximum voluntary tongue protrusion to 39 +/- 19% (TOF, 0.5) and 73 +/- 29% (TOF, 0.8) of baseline; and (4) no effects on upper airway size during expiration, lung volume, and respiratory timing.

CONCLUSIONS

Thus, impaired neuromuscular transmission, even to a degree insufficient to evoke respiratory symptoms, markedly impairs upper airway dimensions and function. This may be explained by an impairment of the balance between upper airway dilating forces and negative intraluminal pressure generated during inspiration by respiratory "pump" muscles.

Irritable bowel syndrome: update on colonic neuromuscular dysfunction and treatment

Recent discoveries regarding the relatively autonomous workings of the enteric nervous system have expanded our understanding of the pathophysiology of irritable bowel syndrome (IBS). However, the heterogeneity of the pathogenesis of IBS continues to create unique challenges for clinicians who care for these patients. Advances in our understanding of the structure and functions of the brain-gut axis and its interplay with other potentially important factors, such as genetic predisposition, inflammation, and psychological unrest, have led to new developments in the field of targeted pharmacotherapy for IBS sufferers. Therapies designed specifically to modulate gut motility, secretion, and/or sensation have been created and introduced into the marketplace in recent years, and additional designer formulations are in various stages of development. Concurrently, new discoveries of potentially beneficial effects of agents approved for other, often non-gastroenterologic, conditions continue to be reported. This article reviews the accumulating body of evidence supporting the importance of neuromuscular dysfunction as a central cause of IBS symptoms and provides a rationale for the discussion of current and future drug development.

Anesthesia for sickle cell disease and congenital myopathy in combination

We report on the perioperative management of anesthesia and analgesia in a child with sickle cell disease and a congenital myopathy, presenting for corrective orthopedic surgery. The case illustrates two valuable points of interest: the many benefits of regional anesthesia in complex medical cases and the successful use of tourniquets in children with sickle cell disease.

Neuro-Ophthalmic Emergencies for the Neurologist

A variety of acute neurologic disorders present with visual signs and symptoms. In this review the authors focus on those disorders in which the clinical outcome is dependent on timely and accurate diagnosis. The first section deals with acute visual loss, specifically optic neuritis, ischemic optic neuropathy (ION), retinal artery occlusion, and homonymous hemianopia. The authors include a discussion of those clinical features that are helpful in distinguishing between inflammatory and ischemic optic nerve disease and between arteritic and nonarteritic ION. The second section concerns disc edema with an emphasis on the prevention of visual loss in patients with increased intracranial pressure. The third section deals with abnormal ocular motility, and includes orbital inflammatory disease, carotid-cavernous fistulas, painful ophthalmoplegia, conjugate gaze palsies, and neuromuscular junction disorders. The final section concerns pupillary abnormalities, with a particular emphasis on the dilated pupil and on carotid artery dissection. Throughout there are specific guidelines for the management of these disorders, and areas are highlighted in which there is ongoing controversy.

Binocular diplopia. A practical approach

BACKGROUND

Diplopia is a common complaint in both inpatient and outpatient neurologic practice. Its causes are many, and special historical and examination features are important to localization and accurate diagnosis.

REVIEW SUMMARY

This review is divided into 2 sections: the first related to diagnosis and the second to treatment of binocular diplopia. In the diagnostic section, emphasis is placed on identification of historical and examination features that can help to differentiate diplopia caused by dysfunction of cranial nerves versus neuromuscular junction, or orbital extraocular muscle. Techniques available to the neurologist for examining ocular motility and ocular misalignment and focused laboratory testing to evaluate diplopia are discussed in detail. The final section covers the various treatments for binocular diplopia, with recommendations regarding the utility of each treatment for different types of diplopia.

CONCLUSIONS

A logical step-by-step approach applied to each patient with diplopia will help prevent misdiagnosis and improve patient care.

Clinical classification of patellofemoral pain syndrome: guidelines for non-operative treatment

The patellofemoral pain syndrome (PFPS) remains a challenging musculoskeletal entity encountered by clinicians. Reviewing the literature, conflicting data seem to exist regarding the effect of non-operative treatment in PFPS patients. A possible explanation may be lack of a clear classification system of patients with PFPS. It is our opinion that the term PFPS still is a 'wastebasket', which probably comprises several different entities. Therefore, it seems important to subdivide this broad group of patients into different categories with a specific rehabilitation approach. In this study, we introduce a classification system, which reflects a consensus reached by the European Rehabilitation Panel. This classification system should help the clinicians to identify the cause(s) of patellofemoral pain, and consequently help to select the most appropriate non-operative treatment. The authors are aware that no rehabilitation protocol will work for all PFPS patients, since the underlying mosaic of pathophysiology and tissue-healing responses are unique. Therefore, the aim of this study with a classification system was to guide the clinician through clinical examination in order to develop a non-operative treatment protocol, specific for each individual with PFPS.

[Epilepsy and myasthenia: a case report]

Epilepsy is 5 to 7 times more frequent among patients with myasthenia than in the general population. Myasthenia gravis is often associated with other affectsion, most of immunological origin. However, hypotheses explaining the association are still uncertain. We report a case of association in a woman who had epilepsy since the age of 9 years and developed myasthenia at the age of 23 years after having discontinued here anti-epileptic treatment for two years.

Acetazolamide acts on neuromuscular transmission abnormalities found in some migraineurs

Mild subclinical impairment of neuromuscular transmission can be detected with single-fibre electromyography (SFEMG) in subgroups of patients suffering from migraine and could be due to dysfunctioning Ca2+-channels on motor axons controlling stimulation-induced acetylcholine release. Acetazolamide, which is thought to ameliorate ion channel function, was shown effective in familial hemiplegic migraine and episodic ataxia type 2, both of which are associated with mutations of the neuronal Ca2+-channel gene CACNA1A, as well as in aura status. We treated therefore in an open pilot study five non-hemiplegic migraineurs showing mild SFEMG abnormalities with acetazolamide for several weeks. This was followed by a normalization of SFEMG recordings in all patients and by clinical improvement in four. These results support the assumption that the subclinical impairment of neuromuscular transmission found in certain migraineurs might be due to dysfunctioning Ca2+-channels.

Neuromuscular junction changes in aged rat thyroarytenoid muscle

Dynamic remodeling of neuromuscular junction (NMJ) structure is postulated as a cause of age-related muscular atrophy. Direct study of NMJ morphology in laryngeal muscles is important to our understanding of age-related decrements in voice and swallowing. The morphology of NMJs was studied in a rat model to compare young and old specimens of thyroarytenoid muscle--a muscle critical to airway protection and phonation. Fluorescent, triple-label immunohistochemical analysis and confocal microscopic visualization were used to analyze the structure of NMJs. We found that laryngeal NMJs underwent significant changes that were similar to those observed after denervation. Specifically, the axon terminal area was significantly reduced, there were a number of postsynaptic acetylcholine receptor areas unoccupied by nerve terminals, and there was increased variability in end plate architecture in the old muscles. The results of this study increase our understanding of the age-related morphological changes in the larynx, and may serve as a baseline to test the effectiveness of future interventions.