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Biomedical subjects

M Nogués

Publications and source records attributed to M Nogués.

At least 19 recordsLinked to original sources
PubMed2002

[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.

Adult↗
PubMed2001

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.

Adrenergic beta-Antagonists↗
PubMed2001

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.

Adult↗
PubMed2001

[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.

Amyotrophic Lateral Sclerosis↗
PubMed2001

[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.

Acute Disease↗
PubMed2001

[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.

Acute Disease↗
PubMed2000

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.

Adolescent↗
PubMed2000

[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.

Adolescent↗
PubMed2000

[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.

Aged↗
PubMed1999

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.

Adolescent↗
PubMed1996

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.

Allosteric Site↗
PubMed1995

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.

Adult↗