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PubMed1989

[Experiences with the "epigastric pain syndrome"].

The report concerns 162 patients suffering from severe upper abdominal pain without organic findings on routine GI-exploration. Palpation of the abdominal wall revealed well localised pain maxima which appeared to correlate with the distribution of intercostal nerve endings. Exploratory local anaesthesia was able to relieve these symptoms whereby - much to our surprise - the therapeutic effect very often outlasted by months and even years the pharmacological effect attributable to the anaesthetic agent. 129 of the 162 patients treated could be significantly improved or even freed of their painful symptoms. Out of the 33 patients with recurring symptoms, three quarters could be cured or significantly improved by separating the subcutaneous fat from the epigastric fascia, thus destroying the cutaneous branches of the intercostal nerves. It seems legitimate to consider the pathogenesis of these symptoms as being due to entrapments of the intercostal nerve endings in the abdominal fascia and it may thus be considered as an organic entity. Diagnosis is relatively easy and without risk for the patient: exploratory local anaesthesia loco dolenti, which in fact may have a long lasting therapeutic effect.

Abdomen↗
PubMed1979

[The distribution of sensory and motor axons of the intercostal nerves and their branches (author's transl)].

As it is well established that motor axons in general display a higher acetylcholinesterase-activity than sensory axons do, the histochemical method of KARNOVSKY and ROOTS (1964) was used for the differentiation of motor and sensory fibres in the intercostal nerves and their branches. In the paravertebral sections of the intercostal nerves of the upper segments 30--35% of the nerve fibres show a high enzyme activity and therefore were classified as motoric. The percentage of the motor fibres in comparable zones of the lower segments increases to 45%. Only 15% of the nerve fibres proved to be motoric in the parasternal sections of the intercostal nerves. In a histogram of the acetylcholinesterase-positive intercostal nerve fibres 2 peaks can be seen: one in the alpha-calibre class, the second in the gamma-class. There are more motor axons in the lateral cutaneous branch of the lower intercostal nerve than in upper ones. This may be explained by the participation of these nerve branches in the innervation of the abdominal muscles. In 2 cases nerve branches of the intercostal nerve to the diaphragm were found containing 15--25% motor axons.

Acetylcholinesterase↗
PubMed1984

Response of respiratory motoneurons to release from vagal inhibition in the rabbit.

Long-lasting effects of vagal input on phrenic (Phr) and external intercostal (EI) motoneuronal output were studied on 16 anesthetized rabbits breathing spontaneously or paralysed and ventilated by a phrenic nerve-driven pump. Withholding of ventilation by tracheal occlusion or by switching off the servorespirator maintained for seven breaths evoked a progressive increase of Phr and EI from breath to breath. This effect was more evident in animals ventilated by servo- respirator. The higher was the gain of the pump (volume-to-phrenic signal ratio) before the maneuvre, the bigger was the rate of increase of the tidal phrenic amplitude from breath to breath at all CO2, levels tested. Vagotomy strongly depressed or eliminated this effect. We conclude that with intact vagus nerve the increase of respiratory motoneuronal output was only partialy due to the gradual increase in chemical drive when ventilation was stopped. The character of the response indicates the existence of a long-lasting component of the Breuer-Hering reflex. Splitting the medulla abolished this prolonged response while preserving the inspiratory vagal inhibition indicates that the neuronal pathways crossing the midline of .the medulla are important for the effect.

Animals↗
PubMed1975

Spinal cord potentials evoked by peripheral nerve stimulation.

Lumbar, thoracic, and cervical spinal cord responses evoked by sciatic nerve stimulation were measured in 20 cats at the skin level and directly from the dorsal surface of the cord. Computer averaging techniques were used for both skin level recordings and cord surface recordings at all levels. Recordings made directly from the cord surface at lumbar levels were large and were characterized by a large, initial, negative transient, followed by a more complicated and variable waveform. As recording electrodes were moved rostrally, the initial large spike decreased in amplitude and the duration and latency of the response increased. At cervical levels were large and were characterized by a large, initial, negative transient, followed by a more complicated and variable waveform. As recording electrodes were moved rostrally, the initial large spike decreased in amplitude and the duration and latency of the response increased. At cervical levels the responses were polyphasic, of long duration and small amplitude. Deafferentation by posterior rhizotomy of all lumbar and sacral roots ipsilateral to sciatic nerve stimulation abolished the response at all levels. Thoracic cord section also abolished the response over the cervical cord. Skin level recordings were of shorter latency than direct recordings, especially at cervical levels. Response configurations were similar for both recording techniques at lumbar levels, but had different waveforms at both thoracic and cervical levels. Clinical implications of the techniques and possible explanations of the waveforms recorded are discussed.

Animals↗
PubMed2001

Electrophysiological recording from neurons controlling sensory and motor functions of the esophagus.

Much work has been done in recent years to understand the functional roles of sensory neurons that regulate reflexes and sensations. Information about the response patterns of spinal dorsal horn and brain stem neurons associated with esophageal functions has become available by using electrophysiological techniques. These techniques allow understanding of response characteristics of neurons to various types of stimuli, neurotransmitters involved in excitation or inhibition of neurons, changes in response characteristics of neurons under pathological conditions, and the shape and size of a particular neuron in the central nervous system, as well as its projection to other areas of the brain. Response properties of primary afferent fibers in the vagus and thoracic sympathetic nerves have been studied in intact animal models by using single-fiber or extracellular microelectrode recording techniques. Recently, the single-fiber recording technique has been used in vitro in isolated esophagus-vagus nerve preparations. Recordings from the brain stem nuclei and thoracic spinal dorsal horn neurons also have examined the response characteristics of second-order neurons receiving afferent input from the esophagus. In the spinal cord, dorsal horn neurons responsive to esophageal distension also receive ipsilateral somatic input (ie, viscero-somatic convergence) from the upper thoracic area. These neurons exhibit sensitization of response after repeated noxious distension of the esophagus or instillation of irritant substances in the esophagus. In the nucleus ambiguus, neurons receiving input from the distal esophagus exhibit excitation to distension of the distal esophagus but undergo inhibition to midthoracic esophageal distension or to swallow. Neurons in the nucleus tractus solitarius receiving input from the distal esophagus exhibit 2 types of responses to proximal and distal esophageal distension. One type of response is a rhythmic firing synchronized with peristaltic contractions of the distal esophagus. This response undergoes inhibition in response to proximal distension. In addition, there is a second, nonrhythmic firing response that occurs both proximal and distal esophageal distension. This observation suggests that swallow-induced inhibition of the distal esophagus is controlled by the preganglionic motor neurons in the brain stem. Electrophysiological studies allow direct understanding of neuronal activities regulating esophageal functions. In vivo recording has an advantage for studying functional roles of the neurons in regulatory reflexes, whereas in vitro recording is useful for more accurate study of receptor pharmacology. Recordings from the central nervous system allow study of the neurotransmitters involved in neuronal function and the circuitry of different reflex mechanisms.

Deglutition↗
PubMed2006

A study exploring the role of intercostal nerve damage in chronic pain after thoracic surgery.

OBJECTIVE: Our aim was to investigate the prevalence of intra-operative nerve damage and its association with chronic pain. METHODS: Our prospective study of 33 patients used nerve conduction studies to assess intercostal nerve function during elective thoracic surgical procedures. We used two methods to study nerve conduction: pre-operative magnetic stimulation (in 10 patients) and intra-operative nerve conduction studies (in all patients) We correlated these findings with specific intra-operative parameters, pain and psychological questionnaires pre-op and 3 month post-op and altered cutaneous sensation. RESULTS: Magstim (magnetic stimulation) assessments were not reliable and were therefore abandoned. Intraoperative intercostal nerve studies revealed two distinct patterns of nerve injury and also that nerve injury was less in those cases where a rib was not resected. However, intercostal nerve damage detected at the time of operation is not associated with chronic pain or altered cutaneous sensation at 3 months post-op. CONCLUSIONS: The study findings suggest that either the amount of intra-operative intercostal nerve damage is not indicative of long-term nerve damage or that there is a more significant cause for chronic pain other than intercostal nerve injury.

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