Lambert–Eaton syndrome (LES) is a rare immune-mediated disorder characterized by proximal leg weakness, autonomic symptoms and hypoactive tendon reflexes. The paraneoplastic form is associated with small-cell lung cancer in 50-60% of cases, whereas the remaining cases are found in younger adults with a higher likelihood of coexisting autoimmune disease. The early recognition of LES is crucial for improving clinical outcomes but remains a major challenge. In this review, we analyze the clinical characteristics and diagnostic considerations in treating LES through a series of three case studies, one of which showed definitive response to pyridostigmine and corticosteroid combination therapy, followed by spontaneous remission. Patients were assessed by image-based screening, serological testing and electrophysiological evaluations, which included respiratory and autonomic testing. A better understanding of the common pitfalls in the clinical, serological and neurophysiologic diagnosis of LES through assessment of typical LES dysfunction throughout the nervous system should enable improved recognition and treatment of this syndrome.

The purpose of this study was to investigate the influence of a diaphragm material on the performance of a microspeaker. The finite element method was adopted to analyze the mode shapes and the displacement of the diaphragm under a force load. The Rayleigh integral was then calculated to determine the radiated sound pressure and frequency response of a loudspeaker. The location of the voice coil was also investigated. Locating the voice coil at approximately 53% to 76% of coil-radius/diaphragm-radius ratio yielded a favorable mode shape distribution and performance for the loudspeaker. In addition, two loudspeaker designs, Models A and B, were analyzed to determine the effects of the diaphragm material. The numerical results of Models A and B, indicated that the mode shape is a crucial factor when considering the materials used in a loudspeaker diaphragm. The property of a material at the inflection point of a mode shape obviously affects the modal frequency. According to this observation, the most crucial first and second axial symmetric modes in a loudspeaker design can be adjusted and the performance can be improved.

The isometric mechanical properties of diaphragm muscle were studied in mice infected with either Trichinella spiralis or Trichinella pseudospiralis. Measurements of muscle stress were taken at 15, 20, 30 and 40 days post-infection. Infected diaphragm muscle showed a significant (P < 0·001) reduction in muscle stress during both twitch and tetanic contractions when compared with muscle from control animals. T. spiralis caused a significant reduction in resistance to muscle fatigue. The consequences of these changes in muscle function to host pathology are discussed, and related to previous work on the effects of Trichinella on host biochemistry and the immune response.

Trichinella spiralis larvae infect and develop within skeletal muscle cells causing major changes to their mechanical properties. The aim of this investigation was to determine the effects of T. spiralis on the power output and fatigue resistance of the mammalian diaphragm under conditions simulating in vivo operation and to relate these to respiratory performance. Infection with T. spiralis leads to major reductions in mechanical stress, work, power output and fatigue resistance. These changes are associated with the number of larvae present in the muscle and the duration of infection. However, the initial decline in mechanical performance occurs during the onset of infection when there are few larvae observed within the muscle cells, indicating that T. spiralis may affect the properties of muscle before encapsulation. This may correspond to the host's inflammatory response and the effects of larval excretory/secretory products. The decline in mechanical performance will have a profound effect on respiration both at rest and during exertion. This must influence the behaviour of the host and increase its chance of capture by predators, which is likely to benefit the parasite by facilitating its transmission.

Weakness of the limbs and respiratory muscles has increasingly been found to be a frequent event that complicates the medical history of patients in Intensive Care. The problem normally affects more serious cases and presents as muscular weakness leading to flaccid paralysis and difficulty in weaning patients off mechanical ventilation. This latter sign leads the intensivist to suspect possible involvement of the neuromuscular respiratory system. Unfortunately, in-depth clinical assessment of the neuromuscular respiratory system is difficult with critically ill patients, and electrophysiological studies have been used instead to overcome this problem. Of these latter, electric and electromagnetic stimulation of the phrenic nerve have been successful (along with needle electromyography of the diaphragm) in identifying the causes of neuromuscular respiratory insufficiency, especially in Intensive Care. In this brief chapter, we will be discussing the technique of electric stimulation of the phrenic nerve and neuromuscular respiratory insufficiency within the field of critical illness polyneuropathy.

The ‘diaphragm’ of Xenopus laevis has close anatomical relations to the lower end of the oesophagus. In mammals, the crural diaphragm acts as a pinch valve at the gastro-oesophageal junction and is an important component of the gastro-oesophageal reflux barrier. The present study analysed the effect of amphibian ‘diaphragm’ contraction on oesophageal pressure using a superfused in situ oesophago-diaphragmatic preparation of large female Xenopus. Three-dimensional reconstruction of the oesophageal pressure profile was performed using four-port oesophageal infusion manometry. Bilateral electrical stimulation of the nerves supplying the ‘diaphragm’ of Xenopus increased the pressure volume vector of 5 mm of oesophagus (centred around the insertions of the diaphragm) from 20.4±16 to 553.6±232 mm.mmHg2 (mean±sd). This was a statistically significant increase and statistically significantly higher than that evoked by electrical stimulation of both vagi (28.1±30.7 mm.mmHg2). The amphibian ‘diaphragm’ seems to be functionally similar to the mammalian crural diaphragm. By analogy, we suggest that the original role of the diaphragm was not respiratory but gastrointestinal.

Background and objective: Non-depolarizing neuromuscular blocking agents have a shorter duration of action on the diaphragm than on skeletal muscles. It was to be tested if this also held true for rapacuronium, a shortacting, amidosteroid non-depolarizing neuromuscular blocker, lately withdrawn from the market, using a novel technique for stimulating the diaphragm and assessing its function.

Methods: Anaesthesia was induced with propofol 2 mg kg−1 and remifentanil 1 μg kg−1, and the trachea was intubated after topical anaesthesia. Rapacuronium was given at a dose of 1.5 mg kg−1. The diaphragm was stimulated by cervical magnetic stimulation of the phrenic nerves (2 Tesla, single coil) and airway pressure responses were measured at the endotracheal tube connector. The neuromuscular effects at the adductor pollicis and orbicularis oculi muscles were measured by acceleromyography.

Results: Fifteen males and five females (ASA I and II; 27 ± 8 yr; 73 ± 13 kg; mean ± SD) were recruited. Median maximal relaxation was less (P < 0.01) for the diaphragm (89%) than for the adductor pollicis or orbicularis oculi muscles (each 100%). The time to 25% recovery was shorter for the diaphragm than for adductor pollicis or orbicularis oculi (7.5 ± 3.1 versus 14.1 ± 3.7 and 15.1 ± 3.5 min, respectively, P < 0.01). Recovery from 25 to 75% was identical for the diaphragm and adductor pollicis (9.4 ± 2.9 versus 9.1 ± 3.5 min), but longer for orbicularis oculi (13.4 ± 4.2 min, P < 0.01). The median recovery time to TOF0.8 was shorter for the diaphragm (23.9 min) than for the adductor pollicis or orbicularis oculi muscles (31.5 and 28.4 min, respectively; P < 0.05).

Conclusions: As with other non-depolarizing muscle relaxants, the duration of the clinical effect of rapacuronium was shorter for the diaphragm than for skeletal muscle. The recovery index was identical for the diaphragm and adductor pollicis.

Eight normal human spinal cords were studied. Spinal segments were identified and embedded in paraffin wax. Serial cross sections were cut at 25 μm and stained by cresyl violet. Motor columns were reconstructed adapting Elliott's (1942) methods. Motor columns were classified into the medial and lateral divisions and were numbered sequentially from medial to lateral at the level of Cl. In the cervical cord, 8 motor columns were traced. Column 1, corresponding to the medial column, presented 3 subdivisions designated as 1a, 1b and 1c with ventral, dorsal and lateral positions respectively. Columns 1a and 1b extended throughout the cervical region while 1c was confined to 3rd, 4th and 5th cervical segments. At the level of C3, 1c was a discrete column situated lateral to 1a and 1b but at C4 and C5 it became displaced medially close to the medial margin of the ventral horn. In cross section, it presented smaller medial and large lateral part. With the help of clinical and developmental evidence an attempt was made to correlate column 1c with the phrenic nucleus.

The dose-related effects of milrinone, a phosphodiesterase (PDE) III inhibitor, on the contractility of fatigued diaphragm were studied in dogs. Animals were divided into three groups of eight each. Diaphragmatic fatigue was induced by intermittent supramaximal bilateral electrophrenic stimulation at a frequency of 20 Hz applied for 30 min. After the production of fatigue, Group I received no study drug; Group II was infused with milrinone (50 mg kg−1 loading dose plus 0.2 mg kg−1 min−1 maintenance dose); Group III was infused with milrinone (50 mg kg−1 loading dose plus 0.5 mg kg−1 min−1 maintenance dose). Diaphragmatic contractility was assessed by measurement of transdiaphragmatic pressure. After the fatigue-producing period, transdiaphragmatic pressure at low-frequency stimulation (20-Hz) decreased from the prefatigued values in all groups (P < 0.05), whereas transdiaphragmatic pressure at high-frequency (100-Hz) stimulation did not change. Compared with Group I, transdiaphragmatic pressure to each stimulus increased during milrinone infusion in Groups II and III (P < 0.05). The increase in transdiaphragmatic pressure was greater in Group III than in Group II (P < 0.05). It is concluded that milrinone is associated with a dose-related effect on the contractility of fatigued diaphragm in dogs.