Britt-Inger Wenngren

Cervicocephalic kinesthetic sensibility, active range of cervical motion, and oculomotor function in patients with whiplash injury

OBJECTIVE To investigate cervicocephalic kinesthetic sensibility, active range of cervical motion, and oculomotor function in patients with whiplash injury. DESIGN A 2-year review of consecutive patients admitted to the emergency unit after whiplash injury. SETTING An otorhinolaryngology department. PATIENTS AND SUBJECTS Twenty-seven consecutive patients with diagnosed whiplash injury (14 men and 13 women, mean age, 33.8yrs [range, 18 to 66yrs]). The controls were healthy subjects without a history of whiplash injury. MAIN OUTCOME MEASURES Oculomotor function was tested at 2 months and at 2 years after whiplash injury. The ability to appreciate both movement and head position was studied. Active range of cervical motion was measured. Subjective intensity of neck pain and major medical symptoms were recorded. RESULTS Active head repositioning was significantly less precise in the whiplash subjects than in the control group. Failures in oculomotor functions were observed in 62% of subjects. Significant correlations occurred between smooth pursuit tests and active cervical range of motion. Correlations also were established between the oculomotor test and the kinesthetic sensibility test. CONCLUSION The results suggest that restricted cervical movements and changes in the quality of proprioceptive information from the cervical spine region affect voluntary eye movements. A flexion/extension injury to the neck may result in dysfunction of the proprioceptive system. Oculomotor dysfunction after neck trauma might be related to cervical afferent input disturbances.

Increased intramuscular concentration of bradykinin increases the static fusimotor drive to muscle spindles in neck muscles of the cat.

Abstract The aim of the present study was to investigate if increased intramuscular concentrations of bradykinin (BK) in one muscle influence the activity in primary and secondary muscle spindle afferents (MSAs) originating from both ipsi‐ and contralateral muscles, via fusimotor reflexes. The ipsilateral trapezius (TR) and the splenius (SP) muscles were subjected to sinusoidal stretches and 2–3 MSAs were simultaneously recorded from these muscles. Responses of 29 MSAs (15 SP and 14 TR) were registered in five adult cats lightly anaesthetised with &agr;‐chloralose. Intramuscular injections of 0.5 ml BK (6–86 &mgr;g/ml) were administered to both the ipsi‐ and contralateral SP and TR muscles. Similar doses of BK (5–10 &mgr;g) have been shown to induce muscle pain when injected into the temporal muscle in man. The responsiveness of the MSAs to the injections of BK was 86% and 87.5% from the contralateral TR and SP muscles, respectively. The effects were predominantly static onto the MSAs. The duration of the effects was on average 3.5–4 min, however some effects lasted for more than 15 min. The effects were always abolished after cutting the nerve to the injected muscle. The large majority of the spindle afferents were unresponsive to i.m. Tyrode injections (23 of 29). For the afferents that were responsive to injection of Tyrode, the effects were always considerably smaller and with shorter duration than those evoked by BK injections. Thus, increased intramuscular concentrations of BK may excite primary and secondary MSAs from ipsi‐ and contralateral muscles, via fusimotor reflexes evoked most probably by activity in chemosensitive muscle afferents. The results are discussed in relation to a recent hypothesis on pathohysiological mechanisms behind genesis, spread and perpetuation of muscle tension and pain in chronic musculoskeletal pain syndromes.

Influences on the γ-muscle spindle system from muscle afferents stimulated by increased intramuscular concentrations of bradykinin and 5-HT

There is evidence that static muscular contractions induce a release of bradykinin (BK) in the working muscle, and that increased concentration of BK and 5-HT in a muscle increases the discharge rate of a subpopulation of group III and group IV muscular afferents. It is also known that activity in group III and IV muscle afferents may activate gamma-motoneurones to both homonymous and heteronymous muscles. The aim of the present study was to investigate whether increased concentration of BK and 5-HT in one muscle may influence the activity in primary and secondary muscle spindle afferents (MSAs) from the chemically affected muscle and from surrounding muscles, via fusimotor reflexes. The experiments were made on six cats anaesthetised with alpha-chloralose. The triceps surae (GS) and the posterior biceps and semitendinosus (PBSt) muscles were subjected to sinusoidal stretches. Simultaneous recordings of 2-11 MSAs from these muscles were made and the mean rate of firing and the modulation for each MSA were determined. Responses of 47 MSAs (26 PBSt and 21 GS) were recorded. The responsiveness of the MSAs to injections of BK (9-100 mg/ml, 0.5-1.0 ml) and 5-HT (25-150 mg/ml, 0.5-1.0 ml) was 89% and 83%, respectively, for injections into the arterial supply of the ipsilateral GS muscle, and 84% and 40% respectively for injections to the contralateral GS muscle. Of 10 secondarŁy MSAs, only one was unresponsive to BK injections, while several MSAs responded to both ipsilateral and contralateral BK injections.(ABSTRACT TRUNCATED AT 250 WORDS)

Influences on the fusimotor-muscle spindle system from chemosensitive nerve endings in cervical facet joints in the cat: possible implications for whiplash induced disorders

&NA; The aim of the present study was to establish if there exists reflex connections from ligamentous structures in cervical facet joints and the fusimotor system of dorsal neck muscles. In seven cats, anaesthetized with &agr;‐chloralose, bradykinin (BK) of concentrations between 12 and 50 &mgr;g was injected into the facet joint between C1 and C2. Recordings were made from single muscle spindle afferents (MSA) originating in contralateral trapezius and splenius muscles (TrSp). Fusimotor induced changes in the sensitivity of the muscle spindle afferents were assessed by recording the responses to sinusoidal stretches of the TrSp muscles. The mean rate of discharge and the depth of modulation of a fitted sine were taken as quantitative estimates of the response. A total of 25 MSAs were recorded, and 21 of these showed clear‐cut alterations in their responses to the sinusoidal stretches following Bk. injections into contralateral facet joint. The majority of the responding afferents (13/21) showed changes in their responses indicating an increased activity of static fusimotoneurones, although responses of dynamic and mixed static and dynamic nature were also seen. Local anaesthetics applied to the intraarticular receptors abolished the effects. Injection (i.v.) of a general anaesthetic (pentobarbital) abolished the effects. The results show that there exist reflex connections between receptors in cervical facet joints and fusimotoneurones of dorsal neck muscles, and this might be of importance in the pathophysiology behind whiplash associated disorders (WAD).

Oculomotor problems after cervical spine injury

Oculomotor function was investigated in 39 patients with a previous soft-tissue injury of the cervical spine. The velocity, the accuracy, and the pattern of the eye movements were disturbed in 20 patients with chronic and disabling symptoms. Oculomotor function in the 19 asymptomatic patients did not differ from a control group. The oculomotor function seems to be impaired, possibly by brain stem lesions, in patients with chronic symptoms of whiplash injury of the cervical spine.

BRADYKININ AND MUSCLE STRETCH ALTER CONTRALATERAL CAT NECK MUSCLE SPINDLE OUTPUT

The objective of this study was to investigate the activity of primary and secondary muscle spindle afferents (MSAs) in neck muscles, when the contralateral splenius or trapezius muscles were (1) exposed to i.m. injection of bradykinin (BK) (6-86 microg/ml), (2) stretched, (3) stretched during exposure to BK or (4) stretched after exposure to BK. It was found that injection of BK, muscle stretch and the combination of the two stimuli significantly excited primary and secondary MSAs via reflex effects onto static fusimotor neurones. BK, alone, and in combination with muscle stretch, induced more frequent, potent and long lasting effects as compared to muscle stretch. The effects of muscle stretch was significantly increased after exposure of BK, indicating that stretch-sensitive nerve-endings within neck muscles are sensitised by BK. The results are discussed in relation to the disturbances in motor co-ordination and proprioception found in patients suffering from chronic muscle pain in the cervical region.

Outcomes of individualized interventions in patients with severe eating difficulties

The aim of this case study is to describe the outcomes of individualized interventions for patients with severe eating difficulties. The participants were 15 patients who had severe eating difficulties following a stroke or brain tumor and were receiving oral feeding or tube feeding. Interventions focused on training functions needed for eating, activities in eating, and discussions with the patient improvements were especially noted in eating activities, and some improvements were noted in oral movements and nutritional status. Before the interventions, none of the patients ate regular food afterward, six did, and in four patients, the feeding tube was removed The patients said eating was easier and they could eat in a safe way. Furthermore, they appreciated the attention to their experience during meals. Although the impairments were not always alleviated, the patients found means to cope with their eating difficulties.

Eye Motility and Auditory Brainstem Response Dysfunction after Whiplash Injury

The aim of this study was to identify the prevalence of brain/brainstem dysfunction after acute whiplash trauma (grades II and III according to the Quebec Task Force Classification on whiplash-associated disorders) and to investigate a possible correlation between the development of chronic symptoms and objective findings from auditory brainstem response (ABR) and eye motility tests. We used ABR and oculomotor tests and a thorough clinical, subjective and psychological evaluation in a sample of prospective whiplash trauma patients who were followed up for 2 years after the trauma. The initial test results did not reveal any prognostic clinical signs for the tested group as a whole, but we could discriminate some patients with clinical symptoms and signs paired with pathologic test results. Over time, some patients normalized clinically and their test results improved while others deteriorated clinically and their test results were worse at the 2-year investigation. Our findings of moderate derangements in the tests could be the effects of pain and/or changed cervical afferent activity at the brain/brainstem level, while eye motility dysfunction, in addition to pathological neuro-otological findings in a small proportion of the patients with severe symptoms, could be explained by lesions to the brain/brainstem.

A frequency-specific auditory brainstem response technique exemplified in the determination of age-related auditory thresholds

Using gated sinusoidal stimuli (tone bursts), frequency-specific auditory brainstem responses (ABR) have been recorded in mice. The gating function represents a filter with a constant narrow bandwidth in the investigated frequency range 2-31.5 kHz. The ABR thresholds found in the CBA/CBA mouse using this technique were in close agreement with those previously reported in the literature concerning mice. The ABR thresholds were analysed in 2-18-month-old animals showing a slight impairment of ABR thresholds with increasing age. The individual variations in ABR thresholds were small.

Vestibular Hair Cell Pathology in the Dancer Mouse Mutant

The morphogenetic type of inner ear defect in the dancer (Dc/+) mouse mutant affects primarily the vestibular part of the labyrinth. The animals show a circling-waltzing behaviour. The inner ears from 7-day to 12-month-old Dc/+ mutants have been analysed. Apart from gross malformations, the gene caused changes in fine structure which were found primarily in the cuticular plate and the stereocilia. As the cuticle gradually disintegrated, the sensory hairs became disarrayed and later showed hair fusion. The combination of the gross malformations and the specific ultrastructural changes in the hair cells probably interferes with both posture and behaviour and, probably together with a dysfunction of the central nervous system, is the cause of the animals behaviour.