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Wilfrid Jänig

Publications and source records attributed to Wilfrid Jänig.

15 recordsLinked to original sources
PubMed2006

Behavioral and sensory changes after direct ischemia-reperfusion injury in rats.

Complex regional pain syndromes (CRPS) are disabling pain syndromes that can develop after trauma or minor tissue injury affecting a limb. Characteristics of CRPS are sensory signs and symptoms, autonomic abnormalities, trophic changes and an impaired motor function. Pathophysiological mechanisms for the development of CRPS are still a matter of investigation. Based on clinical data and investigations of CRPS patients it is hypothesized that tissue hypoxia and inflammation are important for the development of CRPS. The aim of the current study was therefore to examine if direct ischemia-reperfusion injury can induce behavior in rats with symptoms present in patients with CRPS. After baseline behavior measurements the femoral artery of Wistar rats was ligated for 3h with consecutive reperfusion. Sham-operated rats underwent the same preparation except ligation of the artery. Subsequent behavioral testing (observations of spontaneous pain behavior, paw withdrawal to mechanical, noxious mechanical, cold and heat stimuli) was performed up to two months after surgery. Both in rats that underwent ischemia and in sham-operated rats no obvious changes of hindpaw tissue were observed after ischemia-reperfusion injury (trophic changes, edema, differences in skin color or temperature). In behavioral tests only minor changes were observed, these being not different between postischemic rats and sham-operated rats. Using Wistar rats, our data do not support the idea that an ischemia-reperfusion injury can play a major role in the development of CRPS.

Animals↗
PubMed2005

Autonomic dysfunction in rheumatic diseases.

Patients who have rheumatic diseases often present with dysfunctions that are related to the autonomic nervous system (ANS) and are due to peripheral autonomic neuropathy or central changes. This article describes the prevalence of autonomic dysfunctions in patients who have rheumatic diseases. In the second part of this article, another form of ANS dysfunction-complex regional pain syndromes-is demonstrated. Clinically, these syndromes are characterized by pain (spontaneous, hyperalgesia, allodynia); active movement disorders, including an increased physiologic tremor, abnormal regulation of blood flow and sweating, edema of skin and subcutaneous tissues; and trophic changes of skin, appendages of skin, and subcutaneous tissues. In conclusion, this discussion shows that alterations of the ANS occur in rheumatic and related diseases, that these alterations may be involved in the pathogenesis of these diseases, and that we need more refined methods to study the changes that are related to the ANS.

Autonomic Dysreflexia↗
PubMed2003

Complex regional pain syndrome: mystery explained?

Complex regional pain syndrome (CRPS) is the result of changes to the somatosensory systems that process noxious, tactile, and thermal information; to the sympathetic systems that innervate skin (blood vessels, sweat glands); and to the somatomotor systems. The changes suggest that the CNS representations of the systems have been altered. Patients with CRPS also have peripheral changes (eg, oedema, signs of inflammation, sympathetic-afferent coupling [the basis for sympathetically maintained pain], and trophic changes) that cannot be explained by central changes. On the basis of clinical observation and research in human beings and animals, we hypothesise that CRPS is a systemic disease involving the CNS and peripheral nervous system. The most important question for future research is what causes CRPS? In this article, we suggest a change to the focus of research efforts and treatment. We also suggest there be diagnostic reclassification and redefinition of CRPS.

Animals↗
PubMed2003

Ectopic activity in cutaneous regenerating afferent nerve fibers following nerve lesion in the rat.

Spontaneous activity, and mechanical and thermal sensitivity were investigated in regenerating afferent nerve fibers within 4-21 days post sural nerve lesion (crush or transection and resuturing) in anaesthetized rats. About 33-40% of the myelinated (A) and 22-27% of the unmyelinated (C) fibers excited by electrical nerve stimulation exhibited at least one of these ectopic discharge properties. In total 177 A- and 169 C-fibers with ectopic activity were analysed. Most A-fibers (161/177) were mechanosensitive. Spontaneous activity (median 1 imp/s) was present in 23/177 and thermosensitivity in 14/177 A-fibers (13 of them being activated by heat stimuli). Almost all A-fibers (159/177) exhibited only one type of ectopic discharge property. Most C-fibers (94/169) were thermosensitive responding either to cold (n = 45) or to heat stimuli (n = 33) or to both (n = 16). Eighty-four of 169 C-fibers were spontaneously active (median 0.3 imp/s) and 75/169 C-fibers were mechanosensitive. Both the proportion and the discharge rate of spontaneously active C-fibers were significantly higher after crush than after section and resuturing of the nerve. About 60% of the C-fibers (101/169) had only one ectopic discharge property and 40% two or three. In conclusion, regenerating cutaneous afferent A- and C-fibers may develop mechano- and/or thermosensitivity as well as spontaneous activity. We suggest that spontaneous and evoked ectopic activity in regenerating cutaneous afferents are a function of the intrinsic functional properties of these neurons and of the interaction between the regenerating nerve fibers and non-neural cells during Wallerian degeneration in the nerve distal to the nerve lesion.

Action Potentials↗
PubMed2002

Complex regional pain syndrome is a disease of the central nervous system.

Complex regional pain syndrome (CRPS) is clinically characterized by pain, abnormal regulation of blood flow and sweating, edema of skin and subcutaneous tissues, trophic changes of skin, appendages of skin and subcutaneous tissues, and active and passive movement disorders. It is classified into type I (previously reflex sympathetic dystrophy) and type II (previously causalgia). Based on multiple evidence from clinical observations, experimentation on humans, and experimentation on animals, the hypothesis has been put forward that CRPS is primarily a disease of the central nervous system. CRPS patients exhibit changes which occur in somatosensory systems processing noxious, tactile and thermal information, in sympathetic systems innervating skin (blood vessels, sweat glands), and in the somatomotor system. This indicates that the central representations of these systems are changed and data show that CRPS, in particular type I, is a systemic disease involving these neuronal systems. This way of looking at CRPS shifts the attention away from interpreting the syndrome conceptually in a narrow manner and to reduce it to one system or to one mechanism only, e.g., to sympathetic-afferent coupling. It will further our understanding why CRPS type I may develop after a trivial trauma, after a trauma being remote from the affected extremity exhibiting CRPS, and possibly after immobilization of an extremity. It will explain why, in CRPS patients with sympathetically maintained pain, a few temporary blocks of the sympathetic innervation of the affected extremity sometimes lead to long-lasting (even permanent) pain relief and to resolution of the other changes observed in CRPS. This changed view will bring about a diagnostic reclassification and redefinition of CRPS and will have bearings on the therapeutic approaches. Finally it will shift the focus of research efforts.

Central Nervous System↗
PubMed2001

Quantitative sensory testing, neurophysiological and psychological examination in patients with complex regional pain syndrome and hemisensory deficits.

Based on bed-side neurological testing, it has recently been shown that 33% of chronic complex regional pain syndrome (CRPS) type I patients exhibit sensory impairments, which extend past the painful area of the affected limb in a hemisensory distribution (Pain, 80 (1999) 95). In the present study, the clinically observed changes in touch and temperature sensations on the side of the body ipsilateral to the affected limb were investigated quantitatively. Neurophysiological and psychological examinations were conducted to detect changes in the peripheral and central nervous system as well as psychopathological abnormalities. In 40 patients with CRPS, a bed-side neurological examination was performed. Quantitative sensory testing was conducted at five locations on each side of the body. The evaluation of touch thresholds was performed using von Frey filaments (n=40). To measure cool, warm and heat pain thresholds quantitatively, a thermal stimulator using a Peltier-element was used (n=28). With respect to clinical findings, the initiating trauma and severity of abnormalities on nerve conduction testing, three patients were diagnosed as having a reliable CRPS II (causalgia) and five patients a possible CRPS II. Thirty-two patients were diagnosed as having a CRPS I.On clinical examination, 15 patients revealed generalized sensory deficits on the side of the body ipsilateral to the affected limb (hemisensory deficit, n=12; sensory impairment in the upper quadrant of the body, n=3). Patients with these generalized sensory deficits had a significantly longer illness duration (P<0.05) and a significantly higher percentage of mechanical allodynia/hyperalgesia than patients with spatially restricted sensory deficits (n=25) (P<0.05). In patients with generalized sensory impairment, thresholds for touch, warm and cold sensations, and for heat pain were significantly increased at all five locations tested ipsilaterally compared with the contralateral body side, except for the cool threshold on the chest and the heat pain threshold distally on the affected limb. In patients with sensory deficits limited to the affected limb, the touch threshold was significantly higher only in the distal part of the affected limb when compared with the contralateral limb. In these patients, thermal testing revealed almost no differences in cool, warm and heat pain thresholds when comparing both sides. Repeated thermal testing conducted in five patients with generalized sensory impairment reproduced the significant differences between both sides for cool, warm and heat pain thresholds. However, the correlation between the results obtained in the first and second examinations was poor. Neurophysiological recordings revealed pathological results in 46% for nerve conduction studies, 24% for somatosensory evoked potentials and 39% for sympathetic skin response. For all methods applied, there was no statistically significant difference in the incidence of pathological results between patients with generalized and patients with spatially restricted sensory abnormalities. Psychological examination using the structured clinical interview on DSM-IV (SKID) demonstrated a high frequency of affective and anxiety disorders, however, without significant differences between both groups.We conclude that hemisensory impairment in patients with CRPS Type I is probably related to functional disturbances in processing of noxious events in the thalamus and may be a clinical correlate of subcortical brain plasticity in chronic pain.

Adult↗
PubMed2000

Dorsal root section elicits signs of neuropathic pain rather than reversing them in rats with L5 spinal nerve injury.

Mechanical allodynia- and hyperalgesia-like behavior which develops in rats after L5 spinal nerve lesion has been suggested to be due to ectopic activity in the lesioned afferent neurons originating at the lesion site and/or in the dorsal root ganglion because it is eliminated by section of the dorsal root. Here we reevaluated the effect of a dorsal rhizotomy in rats after L5 spinal nerve lesion. Using calibrated von Frey hairs, paw withdrawal threshold to single stimuli and paw withdrawal incidence to repetitive stimulation were tested before and after nerve section. Neuropathic pain behavior of similar time course and magnitude also developed after cutting the L5 dorsal root, and L5 spinal nerve lesion-induced abnormal behavior could not be reversed by dorsal rhizotomy. The neuropathic pain behavior elicited by dorsal root section also developed when impulse conduction in the dorsal root axons was blocked during rhizotomy by a local anesthetic, i.e. when the immediate injury discharge was prevented from reaching the spinal cord. These results challenge the widely accepted idea that neuropathic pain behavior developing after spinal nerve lesion is dependent on ectopic activity in the lesioned afferent neurons. However, the present results do not rule out the possibility that after the two nerve lesions the mechanisms generating neuropathic pain behavior are different. After dorsal rhizotomy neuropathic pain behavior may be related to deafferentation whereas after spinal nerve lesion it may be caused by ectopic activity.

Animals↗
PubMed1991

Receptive properties of pial afferents.

The blood vessels and the pial surface of the brain, spinal cord and its roots are innervated by primary afferent neurones. Here, we have electrophysiologically characterized the functional properties of a subpopulation of these afferent fibres that supply the ventral roots of the cat sacral spinal cord. We have taken advantage of the unique anatomical arrangement of these primary afferent neurones which have their central axon in the dorsal root and project with their peripheral process into the segmental ventral root. In 10 experiments, 14 units were recorded in the dorsal root S2 which responded to electrical stimulation of the segmental ventral root. As judged by their conduction velocity ranging from 0.1 to 2.3 m/sec, all fibres were unmyelinated. In 4 cases a spot-like receptive field was located on the root where the units were reproducibly activated by mechanical stimuli, the most effective being a slight stretch. In two units tested, topical application of hypertonic saline onto the receptive field, but not at other portions of the axon elicited a long-lasting vigorous discharge with intermittent bursts. There was no obvious association of the receptive field with small blood vessels. In 5 of the 14 units including 2 with a mechanosensitive receptive field we observed latency jumps of the action potential with electrical stimulation of the ventral root close to the dorsal root ganglion. In some of these units latency jumps were also observed at other positions when the stimulation electrodes were moved centrally towards the spinal cord. We conclude that a subpopulation of unmyelinated fibres in the spinal ventral root are primary afferents innervating the root proper or its sheath.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

Instrumental investigations in primary headache. An updated review and new perspectives.

While some instrumental techniques are clearly useful for differentiating symptomatic forms from primary headache, the usefulness of certain other techniques, neurophysiological investigations in particular, in clinical practice is still debated. A Task Force of the European Federation of Neurological Societies has recently proposed guidelines and recommendations on the use of neurophysiological tests and neuroimaging procedures in non-acute headache. This article reviews many of the most important literature references relevant to this topic and looks at the prospects for future research.

Blinking↗