[Lambert-Eaton myasthenic syndrome]

INTRODUCTION

Early diagnosis based on clinical findings, neurophysiological studies and serum antibody titres allows early initiation of symptomatic treatment and oncological screening. Reports of patients with LEMS in Latin America are scarce.

AIM

This article aims to describe the characteristics of patients with LEMS from a private centre in Buenos Aires, Argentina, and to compare them with those of other series that have been published.

PATIENTS AND METHODS

The medical records of 13 patients with LEMS with clinical findings, compatible electromyogram and/or positive antibodies were reviewed. Follow-up was performed until associated neoplasia was ruled out or confirmed according to the recommended algorithms.

RESULTS

Four patients were diagnosed with T-LEMS, two of them with small-cell lung carcinoma. Of the nine patients with NT-LEMS, five had a DELTA-P score of 3 and 4. Nine patients presented with the classic clinical triad from the onset of the disease. All patients had electromyogram findings compatible with presynaptic neuromuscular plaque defect. Of the total, 70% improved symptomatically with pyridostigmine.

CONCLUSIONS

The clinical findings, together with compatible neurophysiological studies, are sufficient for the diagnosis of LEMS. The relationship between the DELTA-P score and the risk of small-cell lung carcinoma could not be replicated. Symptomatic treatment with pyridostigmine represents an effective therapeutic alternative.

Vasculitic Peripheral Neuropathy, Differences Between Systemic and Non-Systemic Etiologies: A Case Series and Biopsy Report

BACKGROUND

Vasculitic peripheral neuropathy (VPN) is caused by vessel inflammation leading to peripheral nerve injury of acute-to-subacute onset. When VPN occurs in the context of systemic disease it is classified as Systemic Vasculitic Neuropathy (SVN) and as Non-Systemic Vasculitic Neuropathy (NSVN) when restricted to the nerves.

OBJECTIVE

This study aimed to compare the clinical characteristics, biopsy findings and disease outcome in patients with VPN.

METHODS

Clinical records of adult patients with VPN diagnosed at our institution between June-2002 and June-2019 were retrospectively reviewed. Demographic characteristics, clinical manifestations, nerve conduction studies, nerve biopsies, treatment and clinical evolution were analyzed in all patients with at least 6 months follow-up.

RESULTS

Twenty-five patients with VPN were included (SVN, n = 10; NSVN, n = 15). No significant differences in demographic or clinical features were found between groups. The median delay between symptom onset and nerve biopsy was significantly longer in NSVN patients (10 vs 5.5 months, p = 0.009). Erythrocyte sedimentation rate (ESR) values over 20 mm/h were significantly more common in SVN patients (100% vs. 60%, p = 0.024). Nerve biopsies showed active lesions more frequently in treatment-naive patients compared to those who had received at least 2 weeks of corticosteroids (92% vs 38%; p = 0.03), with a higher proportion of definite VPN cases (92 vs 46%; p = 0.04).

CONCLUSIONS

Although the clinical manifestations are similar, ESR is an important tool to help distinguish between both conditions. Early nerve biopsy in untreated patients increases diagnostic accuracy, avoiding misdiagnosis.

Atraumatic laparoscopic intraperitoneal mesh fixation using a new laparoscopic device: an animal experimental study

PURPOSE

Laparoscopic ventral and incisional hernia repair (LVIHR) has become a common procedure because of its feasibility and safety, but it is not free of complications. Acute and chronic post-operative pain and bleeding caused by traumatic fixation of the mesh are frequently prolonging the hospital stay. The aim of this study was to analyze the behavior of n-butyl-cyanoacrylate (GLUBRAN^® 2) as only mesh fixation METHODS: Ten female pigs were involved in the study and were divided into two groups of five (A and B). Animals in each group underwent a laparoscopic procedure in which two meshes were placed intraperitoneally and fixed with the same synthetic glue only. Animals in group A were sacrificed after 3 weeks, and those in group B were sacrificed after 12 weeks. We studied the morphological, biomechanical, and histological characteristics of the intraperitoneal mesh-tissue interface RESULTS: No disruption, migration or folding was observed in any of the pigs. In group A, the mean tensile strength was 1.4 N/cm (± 0.2) while in group B, the mean tensile strength was 2.5 N/cm (± 0.8). Histological analyses, in areas where mesh was fixed using the glue, showed a chronic lymphocytic inflammatory reaction with a granulomatous component and a marked desmoplastic reaction made up of immature collagen and numerous fibroblasts acquiring myofibroblastic characteristics. In some areas corresponding to fixation, the desmoplastic reaction originated from mature lamellar bone tissue with osteocytes and osteoblasts.

CONCLUSION

Laparoscopic mesh fixation with only the synthetic comonomer glue GLUBRAN^® 2 is feasible, effective, and safe in intraperitoneal incisional/ventral hernia repair in this animal model.

Surgical Dynamometer to Simultaneously Measure the Tension Forces and the Distance between Wound Edges during the Closure of a Laparotomy

The closure of the abdominal wall after making a laparotomy is a major challenge for surgeons, since a significant percentage of closures fail and incisional hernias rise. The suture has to withstand the forces required to close the incision, while not hindering the adequate wound healing progression. Currently, there is no surgical measuring device that could be used to determine the required closing forces, which can be very different depending on the patient. This paper presents a dynamometer to measure the tension forces to be applied while closing a surgical incision, and it simultaneously measures the distance between wound edges. It is a compass-like instrument. A mechanism between the two legs incorporates a load cell, whose signal is read by an electronic device that computes the values of the tension forces between wound edges. An angular position sensor at the pin joint between legs provides the distance between both sides of the incision. Measuring capabilities of the instrument prototype were verified at the laboratory. Thereafter, its functionality was demonstrated in experimental surgery tests. Therefore, the instrument could be very useful in clinical applications, assisting personalized surgical techniques.

High resolution neurography of the brachial plexus by 3 Tesla magnetic resonance imaging

The study of the structures that make up the brachial plexus has benefited particularly from the high resolution images provided by 3T magnetic resonance scanners. The brachial plexus can have mononeuropathies or polyneuropathies. The mononeuropathies include traumatic injuries and trapping, such as occurs in thoracic outlet syndrome due to cervical ribs, prominent transverse apophyses, or tumors. The polyneuropathies include inflammatory processes, in particular chronic inflammatory demyelinating polyneuropathy, Parsonage-Turner syndrome, granulomatous diseases, and radiation neuropathy. Vascular processes affecting the brachial plexus include diabetic polyneuropathy and the vasculitides. This article reviews the anatomy of the brachial plexus and describes the technique for magnetic resonance neurography and the most common pathologic conditions that can affect the brachial plexus.

Definition of linear color models in the RGB vector color space to detect red peaches in orchard images taken under natural illumination

This work proposes the detection of red peaches in orchard images based on the definition of different linear color models in the RGB vector color space. The classification and segmentation of the pixels of the image is then performed by comparing the color distance from each pixel to the different previously defined linear color models. The methodology proposed has been tested with images obtained in a real orchard under natural light. The peach variety in the orchard was the paraguayo (Prunus persica var. platycarpa) peach with red skin. The segmentation results showed that the area of the red peaches in the images was detected with an average error of 11.6%; 19.7% in the case of bright illumination; 8.2% in the case of low illumination; 8.6% for occlusion up to 33%; 12.2% in the case of occlusion between 34 and 66%; and 23% for occlusion above 66%. Finally, a methodology was proposed to estimate the diameter of the fruits based on an ellipsoidal fitting. A first diameter was obtained by using all the contour pixels and a second diameter was obtained by rejecting some pixels of the contour. This approach enables a rough estimate of the fruit occlusion percentage range by comparing the two diameter estimates.

Measuring oscillating walking paths with a LIDAR

This work describes the analysis of different walking paths registered using a Light Detection And Ranging (LIDAR) laser range sensor in order to measure oscillating trajectories during unsupervised walking. The estimate of the gait and trajectory parameters were obtained with a terrestrial LIDAR placed 100 mm above the ground with the scanning plane parallel to the floor to measure the trajectory of the legs without attaching any markers or modifying the floor. Three different large walking experiments were performed to test the proposed measurement system with straight and oscillating trajectories. The main advantages of the proposed system are the possibility to measure several steps and obtain average gait parameters and the minimum infrastructure required. This measurement system enables the development of new ambulatory applications based on the analysis of the gait and the trajectory during a walk.

[Acute bilateral sensorineural hearing loss caused by immuno-mediated inner ear disease]

The audiovestibular system can be affected by an immunologic etiology. The immune-mediated inner ear disease (IMIED) is a syndrome that includes rapidly progressive sensorineural hearing loss, vertigo and tinnitus, which occurs as a primary disorder or complicates certain autoimmune systemic conditions. However, if treated promptly with immunosuppression, the audiological sequel of IMIED may be avoided. We present a 28 year old female patient, who after rhinitis and mioarthralgias developed a vestibular syndrome. A week later she experienced bilateral hearing loss that progressed to deafness in 72 hours. The examination revealed horizontal and torsional nystagmus, a disrupted vestibulo-ocular reflex and vertigo with the positional changes. Laboratory data were normal except for eritrosedimentation rate (75 mm/1 hour). The autoantibodies usually present in rheumatologic autoimmune systemic diseases were negative. The antibodies to the 68-kD antigen found in the inner ear were positive. The chest x-ray and sinus x-ray were normal. The head magnetic resonance imaging with gadolinium and ear computed tomography were normal. Cerebrospinal fluid studies showed normal findings. With the possible diagnosis of IMIED we started early treatment with corticosteroids, with improvement in auditory and vestibular function thereafter. We highlight the early recognition of IMIED as a differential diagnosis in patients with acute bilateral hearing loss, because prompt treatment with immunosuppression might have a positive effect on auditory function recovery.

[Hydrosyringomyelia in demyelinating diseases]

Spinal cord cavitation is a frequent finding in optic neuromyelitis (Devic's syndrome) (DS) but it is also, although rarely, observed in patients with multiple sclerosis (MS). The objective of our study was to compare the MRI characteristics of the syringomyelic cavities in 6 patients with DS and 3 patients with MS. All the patients with DS had a relapsing clinical form with normal brain MRI. Spinal MRI revealed unenhanced central cavities which extended more than 3 vertebral bodies and remained unchanged in follow-up studies. Two patients presented multiple cavities.MS patients suffered a relapsing remitting form of the disease, they all had hyperintense T2 enhancing lesions on their spinal MRI. Moreover spinal MRI also revealed non communicating cavities which extended less than 2 vertebral bodies. Follow-up studies in MS patients revealed a reduction of both the spinal lesions and the cavities. It is still debated whether DS represents a distinct clinical entity different from MS. These findings help distinguishing both disorders in cases when spinal cavities are present and also contribute to the therapeutic choice.

[Acute peripheral demyelinating polyneuropathy and acute renal failure after administration of FK506]

FK 506 is a potent immunosuppressive agent in clinical use in solid organ transplantation since 1989. Approximately 5% of patients receiving FK 506 develop major central nervous system toxicity but peripheral nervous system involvement is very uncommon, and there are only 4 reported cases of demyelinating polyneuropathy in patients who received a liver transplant. We report a case of demyelinating polyneuropathy associated with the use of FK 506 in a renal transplant recipient.

[Multifocal motor neuropathy. Immediate response to intravenous immunoglobulin]

Multifocal motor neuropathy, a rare insidious immune-mediated disorder, features muscular weakness and atrophy, as well as areflexia, due to nerve conduction block and is often associated with the presence of anti-GM1 antibody. We report a patient with a nine-year history of progressive upper limb weakness, misdiagnosed as amyotrophic lateral sclerosis, who responded within hours to intravenous immunoglobulin treatment with full recovery of muscle strength. This case highlights the need to search for conduction block in patients with lower motor neuron involvement.

Postural tachycardia syndrome in syringomyelia: response to fludrocortisone and beta-blockers

Orthostatic intolerance is occasionally reported by patients with syringomyelia and is usually attributed to vestibular symptoms or neurogenic orthostatic hypotension. Postural tachycardia syndrome has not been previously described in syringomyelia. A patient with long-standing syringomyelia and a Chiari type I anomaly developed disabling "panic-like" attacks associated to orthostatic intolerance five years after posterior fossa decompression and shunting of the syrinx. A head-up tilt test showed an early phase of postural orthostatic tachycardia followed by progressive arterial hypotension and bradycardia as seen in neurally mediated syncope. A magnetic resonance imaging scan showed a collapsed syrinx from the 3rd cervical to the 12th thoracic vertebra without syringobulbia. Fludrocortisone and beta-blockers led to resolution of symptoms. Partial sympathetic denervation of the legs in syringomyelia might explain the occasional occurrence of postural tachycardia syndrome. Postural tachycardia syndrome may be included as a possible cause of orthostatic symptoms in syringomyelia patients.

[Chronic hereditary ataxic polyneuropathy]

Sensory ataxic polyneuropathies are characterised by the presence of sensory ataxia due to damage to large myelinated sensory fibres, with total or relative preservation of muscle strength, pain and temperature sensation. Hereditary ataxic polyneuropathies are exceptional and very few families with this disorder have been reported so far. We here describe the neurological, electrophysiological and sural nerve biopsy data of four siblings with an ataxic chronic polyneuropathy, starting after age 50. They had an ataxic gait which worsened in darkness, horizontal nystagmus, hypo or areflexia, and severe impairment of limbs' propriocaption. Nerve conduction studies showed absent sensory nerve action potentials in all nerves tested. Somatosensory evoked potentials showed reduced amplitude and prolonged latencies. Sural nerve biopsy showed a severe loss of myelinated and unmyelinated fibres. Symptoms slowly progressed over the years. The recognition of this syndrome is important in the search for the etiology of chronic ataxic neuropathies.

Focal stiff-person syndrome

Stiff-person syndrome (SPS) is a disorder of motor function characterized by rigidity of axial musculature and fluctuating painful spasms, which are often induced by startle or emotional stimuli. Neurophysiological studies have demonstrated the presence of continuous motor unit activity in muscle at rest, with abnormally enhanced extereoceptive reflexes. Although criteria for the diagnosis of SPS were proposed, several variants of this syndrome have been described before. In this communication, we report the case of a patient with a focal form of SPS. A 39-year-old woman developed progressive instability in her gait, spasms and stiffness restricted to both legs. The electromyographic examination showed continuous motor unit activity of the affected muscles at rest. Moreover, high anti-GAD antibodies titers were found in CSF and serum. Clinical symptoms, electrophysiological and immunological profiles suggest a focal form of SPS. Clinical and immunological findings indicate that SPS is a heterogeneous disease, suggesting the need to redefine its diagnostic criteria. Definition of the range of clinical expression and immunological profiles could be important for the clinical management of these patients.

[Neurological complications of renal transplant]

Advances in surgical procedures and new immunosuppressor therapies have improved the outcome of renal grafts. However, these changes have been accompanied by infectious, neoplastic and neurologic complications. The purpose of this study was to determine the incidence of neurologic complications among 542 patients receiving a renal transplant (from living or cadaveric donors) at CEMIC between 1970 and 1996. Neurologic complications occurred in 43 patients (8%) as follows: 8 meningitis (1.5%), 8 acute confusional syndrome (1.5%), 7 encephalitis (1.3%), 7 cerebrovascular accidents (1.3%), 6 convulsions (1.1%), 3 tumors (0.5%), 3 femoral nerve lesion (0.5%), and 1 epidural lipomatosis (0.1%). Etiologic agents most commonly observed in meningitis were: Cryptococcus neoformans, Listeria monocytogenes and Mycobacterium tuberculosis. Major difficulties arose in the diagnosis of encephalitis. Diagnosis of the above complications required clinical astuteness and repeated bacteriologic, serologic and imaging studies.

Periodic limb movements in syringomyelia and syringobulbia

Twenty-six patients with syringomyelia were studied with polysomnography to determine the frequency of periodic limb movements (PLM) and its relationship to the presence of a Chiari anomaly, the severity of corticospinal tract involvement, and localization of the syrinx. Sixteen patients showed PLM in stages I and II of non-REM sleep and three PLM also while awake. There were no statistically significant differences in overall disability, corticospinal signs, presence of an associated Chiari anomaly, and disease duration between patients with and without PLM, although there was a trend for patients with PLM to have more severe disease. There was preservation of the lumbosacral enlargement of the spinal cord by the syrinx in all patients with PLM. The latency delay between lower and upper limb muscles was suggestive of conduction along propriospinal pathways. Syringomyelia may lead to an abnormal state of spinal hyperexcitability favoring the appearance of PLM. Detailed magnetic resonance image studies of patients with different localizations of the syrinx cavities may help to determine which tracts are involved in the production of PLM.

Respiratory disturbances during sleep in syringomyelia and syringobulbia

OBJECTIVE

To determine the frequency and types of abnormalities of respiratory control during sleep in syringomyelia and syringobulbia and to provide a basis to predict patients at risk of sudden death.

METHODS

Thirty patients (15 male and 15 female; mean age 39.0 +/- 12.6 years) with communicating syringomyelia were divided into two groups: those with evidence of syringobulbia (17 patients) and those without compromise of the medulla or syringomyelia (13 patients). Patients were studied with pulmonary function studies and polysomnography. Respiratory center sensitivity to CO2 (rebreathing technique) was measured in 9 patients.

RESULTS

Severely affected patients had mild-to-moderate restriction and individual patients had bilateral diaphragmatic or vocal cord palsy, abnormal respiratory rhythm, prolonged inspiratory time, or an abnormal respiratory response to CO2. Very prolonged central, obstructive, and mixed sleep apneas with low O2 saturation values and a fixed heart rate were recorded in most patients with syringobulbia. Five patients developed severe respiratory complications and died during a follow-up period of 10 years. Respiratory abnormalities failed to correlate with syrinx size.

CONCLUSIONS

Severe abnormalities in respiratory rhythm generation during sleep occur in patients with syringobulbia. The respiratory disturbances are not due to muscle weakness and they are not correlated with the size of the cavity. The combination of dysphagia and dysphonia in patients with longstanding syringomyelia and syringobulbia predicted likelihood of respiratory disturbances during sleep.

The role of non-catalytic binding subsites in the endonuclease activity of bovine pancreatic ribonuclease A

Bovine pancreatic ribonuclease A catalyzes the depolymerization of RNA. There is much evidence that several subsites, in addition to the main catalytic site, are involved in the formation of the enzyme-substrate complex. This work analyzes the pattern of oligonucleotide formation by ribonuclease A using poly(C) as substrate. The poly(C) cleavage shows that the enzyme does not act in a random fashion but rather prefers the binding and cleavage of the longer substrate molecules and that the phosphodiester bond broken should be 6-7 residues apart from the end of the chain to be preferentially cleaved by ribonuclease A. The results demonstrate the model of the cleavage of an RNA chain based on the cooperative binding between the multisubsite binding structure of ribonuclease A and the phosphates of the polynucleotide (Parés, X., Nogués, M. V., de Llorens, R., and Cuchillo, C. M. (1991) in Essays in Biochemistry (Tipton, K. F., ed) Vol. 26, pp. 89-103, Portland Press Ltd., London). The contribution to the enzymatic process of the non-catalytic phosphate-binding subsite (p2) adjacent to the catalytic center has been analyzed in p2 chemically modified ribonuclease A or by means of site-directed mutagenesis. In both cases deletion of p2 abolishes the endonuclease activity of ribonuclease A, which is substituted by an exonuclease activity. All these results support the role of the multisubsite structure of the enzyme in the endonuclease activity and in the catalytic mechanism.

Single fiber electromyography of extraocular muscles: a sensitive method for the diagnosis of ocular myasthenia gravis

We performed single fiber electromyography (SFEMG) in the superior rectus and levator palpebralis (SR-LP) muscles of 17 patients with pure ocular myasthenia gravis (MG) and 9 controls. Thirteen patients were also assessed with SFEMG in the orbicularis oculi (OO) muscle. All the MG patients but none of the control subjects showed abnormal SFEMG jitter in the SR-LP muscles. On the other hand, only 62% of the MG patients had abnormal SFEMG jitter in the OO muscle. The procedure was well tolerated by the patients, and complications were minor. We conclude that SFEMG of the SR-LP muscles is a safe and highly sensitive technique for the diagnosis of ocular MG.

Masticatory muscle spasm in a non-Japanese patient with Satoyoshi syndrome successfully treated with botulinum toxin

A non-Japanese patient with Satoyoshi syndrome is presented. Severe masticatory muscle spasms interfered with feeding, but were successfully treated with botulinum toxin.

Paroxysmal alien hand syndrome

Four patients are described who presented with a paroxysmal form of the alien hand syndrome. Two patients with damage to one frontomedial cortex had brief episodes of abnormal motor behaviour of the contralateral arm that featured groping, grasping, and apparently purposeful but perseverative movements, which both patients interpreted as alien or foreign. The other two patients, with posterior parietal damage, reported a paroxysmal feeling of unawareness of the location of the contralateral arm, lack of recognition of the arm as their own, purposeless movements, and personification of the arm. These cases represent a new form of the alien hand syndrome manifested by brief, paroxysmal episodes, which may be due to ictal mechanisms.

Inverse masticatory muscle activity due to syringobulbia

The clinical, radiological, and electrophysiological data of a 25-year-old woman with "inverse masticatory muscle activity" due to syringobulbia is presented. This uncommon brain stem syndrome may be due to a disturbance in central programming of mastication.

Gyratory epilepsy in a patient with a thalamic neoplasm

A patient with a right thalamic oligodendroglioma developed seizures characterized by circling behavior, speech arrest, and secondarily generalized seizures. Gyratory epilepsy is relatively uncommon and may either represent a benign form of primary generalized epilepsy or occur secondary to a focal cortical lesion. Thalamic stimulation has been shown experimentally to induce circling movements, but no other clinical cases with a thalamic lesion have been described.

Ischemic infarction in 25 children with tuberculous meningitis

Twenty-five cases (38%) of ischemic infarction occurred among 65 cases of tuberculous meningitis in patients less than 14 years of age. The male:female ratio was 1.3:1. The most frequent clinical findings were meningeal signs, fever, alteration of consciousness, cranial nerve involvement, seizures, and focal neurologic deficit. Twenty-three patients had anterior circulation infarcts, and two more had infarcts in the vertebrobasilar territories. Distribution of infarcts in the anterior circulation was shown by computed tomography in the territories of the following arteries: lenticulostriate, 10 cases unilateral and 6 bilateral; middle cerebral, 3 cases; internal carotid, 1 case; multiple areas, 3 cases. Of the 25 ischemic infarction cases, 23 (92%) had hydrocephalus, 19 (76%) basal exudates, and 2 (8%) tuberculomas. Outcome was poor since no patient with infarction recovered completely. Six died and bilateral subcortical infarcts led to a considerably higher mortality than unilateral ones, whether cortical or subcortical.