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C F Bolton

Publications and source records attributed to C F Bolton.

At least 55 records · Page 3Linked to original sources
PubMed1996

Motor neuron disease presenting as acute respiratory failure: a clinical and pathological study.

Respiratory failure is rarely a presenting symptom of motor neuron disease. Seven patients with motor neuron disease who presented with acute respiratory failure of unknown cause and required mechanical ventilation were studied. They all had symptoms and signs suggestive of diaphragmatic weakness. Respiratory involvement seemed disproportionately severe, as six were ambulatory and only three noted limb weakness. Only one had tongue weakness and none had swallowing difficulty. Electrophysiological studies showed widespread denervation and, in particular, diaphragmatic involvement to explain the severe respiratory failure. Weaning from the ventilator was unsuccessful in all cases. The four patients examined at necropsy showed severe loss of anterior horns cells in the cervical cord, with only minimal upper motor neuron involvement. Motor neuron disease should be recognised as a cause of acute respiratory failure, secondary to diaphragmatic paralysis from involvement of phrenic motor neurons.

Acute Disease↗
PubMed1996

The cortical representation of somatosensory evoked potentials of the phrenic nerve.

Respiratory electrophysiological studies are of essential value in diagnosing and managing patients with respiratory failure, but assessment of the sensory phrenic nerve fibres has been neglected. We recorded phrenic nerve somatosensory evoked potentials (SSEPs) by combining neurophysiological and neuroimaging techniques in three healthy subjects. Evoked potentials of the phrenic nerve showed the highest amplitude at CP3, determined by the modified 10-20 EEG system, and occurred at a constant latency, PI at 12.0 +/- 0.6 ms, and NI at 17.3 +/- 0.8 ms. Single photon emission computer tomography (SPECT) performed during phrenic nerve stimulation revealed focal neuronal activation in the somatosensory pathways. Intravenously administered Tc-99m Ethyl Cysteinate Dimer (ECD) was used as a blood flow tracer to obtain baseline and activated images. After image registration, baseline images were compared voxel-by-voxel with the activation images. The mean inter-subject summation image of the activated state was compared with that of the baseline state using ten normal subjects. The extent of the total voxel volume increase on the mean images of the 3 activated SPECT images was 0.7%, and a mean signal increase of 22%. For further anatomic localization of regional increases in signal, the magnetic resonance image (MRI) scan of each subject was registered and superimposed on the activated stage SPECT image. This method may be used clinically to study the pathophysiology of impaired central respiratory drive.

Adult↗
PubMed1996

Infections.

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AIDS-Related Opportunistic Infections↗
PubMed1996

Neuromuscular disorders in critical illness.

Neuromuscular disorders are important causes of prolonged morbidity in intensive care unit. Specific disorders facing the neurologist in the intensive care unit may have been present before admission to the unit or develop as a secondary complication of their stay. A bedside neurological examination, followed by electrophysiological testing, including testing of the respiratory system, is crucial in providing the neuromuscular diagnosis. Among the neuromuscular disorders that confront the clinician in the unit are motor neuron disease, acute polyneuropathies including acute inflammatory demyelinating polyneuropathy (Guillain-Barré syndrome) and critical illness polyneuropathy, neuromuscular transmission disorders including myasthenia gravis, and specific myopathies. This chapter reviews the differential diagnosis and the unique features of neuromuscular conditions that may complicate critical illness and admission to the intensive care unit.

Critical Care↗
PubMed1995

Phrenic nerve conduction study in normal subjects.

Phrenic nerve conduction studies were performed in 50 phrenic nerves from 25 normal subjects using a technique modified from previously described methods. The normal ranges for latency, amplitude, negative peak area, and duration were established. The latency correlates with age and the amplitude increases with chest circumference. With our method, the amplitude increases and the duration decreases with lung volume. We found good right-left agreement and reproducibility. Therefore, the unaffected side can be used as a reference in unilateral phrenic nerve lesions and previous studies can be used for comparison in serial studies. We recommend that phrenic nerve conduction studies be used routinely to diagnose and monitor patients with respiratory involvement from neuromuscular diseases.

Action Potentials↗
PubMed1995

Neuromuscular disorders associated with failure to wean from the ventilator.

OBJECTIVE: To determine, by retrospective chart analysis, the frequency, type and significance of neuromuscular disorders in patients whose clinical features suggested a neuromuscular cause of failure to wean. BACKGROUND: Failure to wean is a common and difficult problem in critical care units. While a neuromuscular cause may be suspected in some patients, the frequency and type has not been determined utilizing comprehensive electrophysiological studies of limbs and the respiratory system. Such knowledge may aid in patient management and prognosis. METHODS: The clinical setting was a critical care/trauma centre that admits 1500 patients per year, approximately 500 being on ventilators for longer than five days. We analyzed the hospital charts of 40 patients admitted to the unit during three years, whose respiratory assessment suggested a neuromuscular cause for failure to wean from the ventilator. To investigate this possibility, we performed electrophysiological studies of the limbs and also of the respiratory system by phrenic nerve conduction and needle electromyography of the chest wall and diaphragm. The results were compared to 25 healthy controls. RESULTS: 38 of 40 patients (95%) had a neuromuscular disorder: 25--critical illness polyneuropathy, 2--Guillain-Barré syndrome, 4--diabetic and critical illness polyneuropathy, 2--uremic and critical illness polyneuropathy, 10--an abnormality of central drive, 5--unilateral phrenic nerve palsy, 3--a neuromuscular transmission defect, and 5--a primary myopathy. Fifteen (38%) had a combination of disorders. Patients with more severe polyneuropathy took longer to wean, a mean of 136 versus 52 days (p = 0.007). The severity of the polyneuropathy had no effect on mortality. CONCLUSIONS: Electrophysiological studies of limbs and the respiratory system are together valuable in confirming the presence, and identifying the specific type of neuromuscular cause for difficulty in weaning from the ventilator. This information is important in patient management and prognosis.

Adolescent↗
PubMed1995

Electrophysiological study of diaphragmatic myoclonus.

This is the first reported detailed electrophysiological study of diaphragmatic myoclonus. An 86 year old woman had rapid, intermittent epigastric pulsations. Neurological examination and imaging studies of the brain and spinal cord were normal. Needle EMG showed rhythmic contractions of the diaphragm and external intercostal muscles at 4 to 5 Hz. These contractions were often associated with suppression of normal breathing and were capable of maintaining adequate ventilation. Both diaphragms were involved but showed considerable variability in their relative latencies. Automated interference pattern analysis suggested a change in recruitment order, with selective activation of large phrenic motoneurons. The supraspinal mechanisms mediating diaphragmatic myoclonus are different from that of voluntary and involuntary rhythmic breathing, and seem to be unrelated to palatal myoclonus. The generator source is likely related to respiratory centres in the rostral medulla.

Aged↗
PubMed1995

Neuromuscular complications of sepsis in children.

Sepsis occurs frequently in the pediatric intensive care unit and is a significant cause of morbidity and mortality. Multiple organ systems are adversely affected by sepsis. Approximately 70% of adult patients with sepsis have peripheral nervous system dysfunction on electrophysiologic studies, of whom 30% are symptomatic. Neuromuscular dysfunction in children with sepsis is increasingly reported; however, the incidence remains undefined. Flaccid quadriplegia with the inability to wean from ventilatory support despite full cardiopulmonary recovery is the typical presentation. However, lesser degrees of weakness may be demonstrated with careful evaluation. Electrophysiologic studies often demonstrate the presence of axonal polyneuropathies, abnormalities of neuromuscular transmission, or acute myopathies. Identifiable neuromuscular syndromes in children with sepsis include critical illness polyneuropathy, pure motor polyneuropathy, thick-filament myopathy, and necrotizing myopathy. The common underlying pathogenic process in these syndromes appears to be sepsis, which may be accentuated by the administration of steroids or neuromuscular blocking agents. Recovery in strength usually occurs over a period of weeks to months.

Adult↗
PubMed1994

Nerve biopsy findings in Niemann-Pick type II (NPC)

The severe infantile form of Niemann-Pick disease type II was diagnosed in a 4-year-old girl and confirmed by demonstrating in cultured skin fibroblasts a deficiency of low-density lipoprotein-stimulated cholesterol ester synthesis of < 5% of normal. Electrodiagnostic studies revealed changes of a predominantly demyelinating motor and sensory polyneuropathy. Light microscope and ultrastructural examination of a peroneal nerve biopsy showed unique changes. Compacted myelin sheaths were disproportionately thin with marked globular irregularities in single teased nerve fibres and evidence of chronic demyelination. The majority of axons were preserved but axonal spheroids and cytoskeletal abnormalities akin to neuroaxonal dystrophy were noted. Membrane-bound multi-lobulated lysosomal inclusions of floccular and electron-dense material were present in Schwann cells (SC), endoneurial fibroblasts, macrophages, pericytes and endothelial cells. SC of myelinated fibres were stuffed with whorls of concentric osmiophilic membraneous profiles and electron-lucent material. The findings are diagnostic and differ from those of classical Niemann-Pick disease.

Axons↗
PubMed1994

Assessment of respiratory function in the intensive care unit.

Disorders of both the central and peripheral nervous systems are important causes of respiratory insufficiency. However, simple clinical observations and pulmonary function measurements may fail to identify the location and type of disorder. This can often be accomplished by the newly-developed technique of phrenic nerve conduction and needle electromyography of the diaphragm which delineate the various disturbances of central drive, axonal or demyelinating neuropathies of the phrenic nerves and certain myopathies. These studies have been preformed safely and with little discomfort on adults, children or infants, and in out-patient and general ward settings. We have found they are of particular value in the intensive care unit.

Adult↗
PubMed1993

The neurological complications of sepsis.

Encephalopathy and polyneuropathy occur in 70% of septic patients. The encephalopathy is diffuse, appears early, is often severe, but reverses quickly with successful treatment of the sepsis. The electroencephalogram is a sensitive indicator of the incidence and severity of the encephalopathy, but computed tomograms of the brain and cerebrospinal fluid findings are unremarkable. Critical-illness polyneuropathy develops later and in association with multiple-organ failure. Recovery is more gradual. Difficulty in weaning from the ventilator is an important early manifestation. Electromyography should be routinely performed to establish the diagnosis. The polyneuropathy is a primary axonal degeneration, predominantly of distal motor fibers. A persistent deficit may eventuate in severe cases. Whether muscle is affected as consistently as brain and peripheral nerve, and by the same process, has not been determined. Medications used in critical care units, notably sedatives and neuromuscular blocking agents, often confuse the clinical picture. The neurological pathophysiology is unknown but current evidence suggests that nervous system dysfunction arises through the same mechanisms as for systemic organs in the septic syndrome.

Brain Diseases↗
PubMed1993

AAEM minimonograph #40: clinical neurophysiology of the respiratory system.

Disorders of nerve and muscle are frequent causes of respiratory insufficiency, but current methods often fail to adequately assess the problem. Phrenic nerve conduction and needle electromyography of the diaphragm are of great assistance in identifying the nature and site of the disorder: the various disturbances of central drive, axonal or demyelinating neuropathies of the phrenic nerves, and certain myopathies. These studies may be performed on adults, children, or infants, and in outpatient, general ward, or critical care settings. It is hoped these techniques will stimulate further developments in the field.

Brain↗