The BH3-mimetic ABT-737 induces mast cell apoptosis in vitro and in vivo: potential for therapeutics

Mast cells and their mediators are implicated in the pathogenesis of many different diseases. One possible therapeutic intervention in mast cell-associated diseases can be to reduce the number of tissue mast cells by inducing mast cell apoptosis. In this study, we demonstrate that mast cells exhibit a high sensitivity to ABT-737, a BH3-only mimetic molecule that induces apoptosis through high-affinity binding to the prosurvival proteins, Bcl-2, Bcl-XL, and Bcl-w. Primary mast cells as well as mast cell lines tested succumbed to apoptosis in response to the inhibitor at varying but seemingly low concentrations compared with other leukocytes investigated. I.p. injections of ABT-737 in mice resulted in a total abolishment of mast cells in the peritoneum. Confocal microscopy analysis of peritoneal cells revealed apoptotic bodies of mast cells being phagocytosed by macrophages. In addition, ex vivo treatment of human skin biopsies with ABT-737 demonstrated increased mast cell apoptosis. The data we present in this article show exceptional mast cell sensitivity to ABT-737, a selective inhibitor of antiapoptotic proteins, rendering a possible application for BH3-only mimetic compounds like ABT-737 in mast cell-associated diseases, such as mastocytosis, allergy, asthma, and other chronic inflammations.

Pro-apoptotic Bax is the major and Bak an auxiliary effector in cytokine deprivation-induced mast cell apoptosis

The process of apoptosis in immune cells like mast cells is essential to regain homeostasis after an inflammatory response. The intrinsic pathway of apoptosis is ultimately controlled by the pro-apoptotic Bcl-2 family members Bax and Bak, which upon activation oligomerize to cause increased permeabilization of the mitochondria outer membrane leading to cell death. We examined the role of Bax and Bak in cytokine deprivation-induced apoptosis in mast cells using connective tissue-like mast cells and mucosal-like mast cells derived from bax^−/−, bak^−/− and bax^−/−bak^−/− mice. Although both Bax and Bak were expressed at readily detectable protein levels, we found a major role for Bax in mediating mast cell apoptosis induced by cytokine deprivation. We analyzed cell viability by propidium iodide exclusion and flow cytometry after deprivation of vital cytokines for each mast cell population. Upon cytokine withdrawal, bak^−/− mast cells died at a similar rate as wild type, whereas bax^−/− and bax^−/−bak^−/− mast cells were partially or completely resistant to apoptosis, respectively. The total resistance seen in bax^−/−bak^−/− mast cells is comparable with mast cells deficient of both pro-apoptotic Bim and Puma or mast cells overexpressing anti-apoptotic Bcl-2. These results show that Bax has a predominant and Bak a minor role in cytokine deprivation-induced apoptosis in both connective tissue-like and mucosal-like mast cells.

Prognostic and predictive value of thymidylate synthase expression in primary colorectal cancer

AIM

To investigate thymidylate synthase (TS) expression in primary colorectal cancer (CRC) as a prognostic and predictive marker of benefit for adjuvant chemotherapy.

PATIENTS AND METHODS

TS expression was immuno0-histochemically (IHC) assessed on tumors from 1,389 patients with stage II and III CRC randomly assigned to either surgery alone or surgery plus 5-fluorouracil (5-FU)-based adjuvant chemotherapy.

RESULTS

In the subgroup treated with surgery alone (n=708), TS expression was prognostic using the classification of TS 0-1 versus 2-3 (p=0.045) as well as TS classified as 0-2 versus 3 (p=0.002). A high TS expression was associated with a shorter overall survival. Among patients with TS grade 3 (n=460), the subgroup treated with adjuvant chemotherapy had a significant longer OS (p=0.005).

CONCLUSION

In this study TS, immunohistochemically assessed, is a prognostic factor in CRC patients treated with surgery alone. Patients with the highest level of TS expression (grade 3) had an improved clinical outcome following adjuvant 5-FU-based chemotherapy.

Change of body movement coordination during cervical proprioceptive disturbances with increased age

BACKGROUND

To date, there are very few studies on postural stability in older adults using body movement recordings to capture the postural movement pattern. Moreover, the importance of proprioception at key areas such as the calf or neck on the postural movement pattern in older adults has rarely been investigated.

OBJECTIVE

To investigate whether the body movement coordination strategy to calf or neck vibration was affected by aging.

METHODS

Body movement measurements were taken at five locations (ankle, knee, hip, shoulder and head) from 18 younger (mean age 29.1 years) and 16 older (mean age 71.5 years) adult subjects using a 3D movement measuring system while subjected to 50 s of pseudo-random calf or neck vibratory stimulation pulses with eyes open or closed. The positions from the knee, hip, shoulder and head markers were correlated against one another to give an indication of the body coordination.

RESULTS

During quiet standing, older adults had greater correlation between the head and trunk than the young. There was an age effect in the body movement coordination strategy. Older adults had a different movement pattern with neck vibration involving mainly more independent knee movements, indicating balance difficulty.

CONCLUSIONS

Neck vibration affects the movement pattern in older adults more compared with younger adults and calf vibration, suggesting that, the regulation of body orientation in older adults is more difficult, especially during cervical proprioceptive disturbances.

Vestibular PREHAB and gentamicin before schwannoma surgery may improve long-term postural function

BACKGROUND

Unilateral vestibular deafferentation (uVD), as performed in vestibular schwannoma surgery, results in a chronic vestibular deficit, though most of the insufficiency can be compensated by other sensory input. By vestibular training (prehabituation) performed before surgery, motor adaptation processes can be instigated before the actual lesion. The adaptation processes of the altered sensory input could be affected if the vestibular ablation and surgery were separated in time, by pretreating patients who have remaining vestibular function with gentamicin.

OBJECTIVE

To determine whether presurgical deafferentation would affect postsurgery postural control also in a long-term perspective (6 months).

METHOD

41 patients subjected to trans-labyrinthine schwannoma surgery were divided into four groups depending on the vestibular activity before surgery (with no clinical significant remaining function n = 17; with remaining function n = 8), whether signs of central lesions were present (n = 10), and if patients with remaining vestibular activity were treated with gentamicin with the aim to produce uVD before surgery (n = 6). The vibratory posturography recordings before surgery and at the follow-up 6 months after surgery were compared.

RESULTS

The subjects pretreated with gentamicin had significantly less postural sway at the follow-up, both compared with the preoperative recordings and compared with the other groups.

CONCLUSION

The results indicate that by both careful sensory training and separating the surgical trauma and the effects of uVD in time, adaptive processes can develop more efficiently to resolve sensory conflicts, resulting in a reduction of symptoms not only directly after surgery but also perhaps up to 6 months afterwards.

Bcl-2 and Bcl-XL are indispensable for the late phase of mast cell development from mouse embryonic stem cells

OBJECTIVE

The aim of this study was to determine the importance of the prosurvival factors Bcl-2 and Bcl-XL for mast cell development and survival.

METHODS

bcl-x(-/-) and bcl-2(-/-) mouse embryonic stem cells were maintained in medium supplemented with either interleukin (IL)-3 or IL-3 in combination with stem cell factor (SCF) to favor mast cell development. The development of Bcl-2 family deficient embryonic stem cell-derived mast cells (ESMCs) was monitored and Bcl-2 family gene expression and cell numbers were analyzed.

RESULTS

Deficiency in either bcl-x or bcl-2 totally inhibited the development of ESMCs when IL-3 alone was used as a mast cell growth factor. Intriguingly, when IL-3 was used in combination with SCF, the ESMCs developed normally the first 2 weeks but thereafter the cell numbers dropped drastically. The remaining ESMCs express mouse mast cell protease 1, suggesting a mucosal-like phenotype. ESMCs lacking bcl-x or bcl-2 exhibited strong expression of A1, another prosurvival Bcl-2 family member.

CONCLUSION

For the first time we provide direct evidence that both bcl-x and bcl-2 are indispensable for mast cell survival during the late phase of their development.

Immunohistochemical test for MLH1 and MSH2 is an independent prognostic factor in sporadic colorectal cancer

4126

Background: Microsatellite instability (MSI) is the hallmark of a defective DNA mismatch repair (MMR) and occurs in 10- 20 % of sporadic colorectal cancer (CRC). The loss of the MLH1 protein is the cause of MSI in almost all sporadic colorectal MSI tumours. The second most common protein to be lost is MSH2. There is evidence that MSI is a prognostic factor in CRC. The role of MSI status as a predictive factor of benefit from adjuvant 5-fluorouracil (5-FU) based chemotherapy is controversial. Methods: Monoclonal antibodies that recognize the mismatch repair protein by immunohistochemistry (IHC) have been commercially available for several years. Previous reports have found a strong correlation between MMR results obtained by immunohistochemical and genetic analysis. This study included 1006 CRC patients (488 Stage II and 518 Stage III) with a median follow-up of 5 years. The patients were included in Nordic trials randomised between surgery alone and surgery plus adjuvant 5-FU. The MMR status was retrospectively assessed on paraffin-embedded formalin-fixed samples using IHC. Results: One hundred fifty seven patients (15.6 %) showed a loss of MMR protein expression (139 MLH1 negative, 15 MSH2 negative and 3 MLH1+MSH2 negative) and were classified as MMR protein negative. A normal MMR protein expression was found in 851 patients who were defined as MMR protein positive. The median overall survival (OS) was 84 months (range 2–181 months). MMR protein expression was a significant prognostic marker in the entire study group where a better OS was seen among patients with MMR protein negative carcinomas compared to patients with MMR protein positive tumours (p=0.005). In multivariate analysis the MMR protein expression was significantly associated with OS, (hazard ratio for death, 0.67 [95 per cent confidence interval, 0.38 to 0.96]; p=0.008). However, in this study the MMR status did not predict response to 5-FU adjuvant chemotherapy. Conclusions: This study reveals that immunohistochemical analysis of MLH1 and MSH2 expression can yield important prognostic information but is not a predictive factor in sporadic CRC.

No significant financial relationships to disclose.

Cervical muscle afferents play a dominant role over vestibular afferents during bilateral vibration of neck muscles

A previous study showed that vibratory stimulation of neck muscles in humans induced short-latency electromyographic (EMG) activation of lower leg muscles, producing postural reactions at the feet. These findings indicated that cervical proprioception contributes to stabilization of stance through rapidly integrated pathways. However, as vibration may excite both proprioceptive and vestibular afferents, and because of the proximity of neck muscles to the vestibular apparatus, neck muscle vibration could also have activated the vestibular system thereby contributing to the effect observed. To investigate any possible contribution of vestibular stimulation, vibratory stimuli were applied bilaterally and separately to the splenius muscles of the neck and the planum mastoideum overlying the vestibular organs. Ten normal subjects, with eyes closed, were exposed to vibratory stimulation of two different amplitudes and frequencies. Responses were assessed by EMG activity recorded from tibialis anterior and gastrocnemius muscles of both legs and by changes in center of pressure as measured by a force platform. Results indicated that vibration induced reproducible EMG and postural responses in the anteroposterior direction, particularly on cessation of vibration. EMG and postural responses were considerably lower and less consistent with mastoid vibration compared with neck muscles vibration. Previous reports suggest that vibratory stimulation could propagate to the vestibular organs and generate a vestibular-induced postural activation. However, our findings indicate that cervical muscles afferents play a dominant role over vestibular afferents when vibration is directed towards the neck muscles.

Mondini-like malformation mimicking otosclerosis and superior semicircular canal dehiscence

In 2003, it was reported that superior semicircular canal dehiscence can mimic otosclerosis because of low-frequency bone conduction hearing gain and dissipation of air-conducted acoustic energy through the dehiscence. We report the case of a 17-year-old girl with left-sided combined hearing loss thought to be due to otosclerosis. Bone conduction thresholds were -10 dB at 250 and 500 Hz and she had a 40 dB air-bone gap at 250 Hz. When a tuning fork was placed at her ankle she heard it in her left ear. Acoustic reflexes and vestibular evoked myogenic potentials could be elicited bilaterally. Imaging of the temporal bones showed no otosclerosis, superior semicircular canal dehiscence or large vestibular aqueduct, but a left-sided, Mondini-like dysplasia of the cochlea with a modiolar deficiency could be seen. Mondini-like cochlear dysplasia should be added to the causes of inner-ear conductive hearing loss.

Cervical muscle afferents play a dominant role over vestibular afferents during bilateral vibration of neck muscles

A previous study showed that vibratory stimulation of neck muscles in humans induced short-latency electromyographic (EMG) activation of lower leg muscles, producing postural reactions at the feet. These findings indicated that cervical proprioception contributes to stabilization of stance through rapidly integrated pathways. However, as vibration may excite both proprioceptive and vestibular afferents, and because of the proximity of neck muscles to the vestibular apparatus, neck muscle vibration could also have activated the vestibular system thereby contributing to the effect observed. To investigate any possible contribution of vestibular stimulation, vibratory stimuli were applied bilaterally and separately to the splenius muscles of the neck and the planum mastoideum overlying the vestibular organs. Ten normal subjects, with eyes closed, were exposed to vibratory stimulation of two different amplitudes and frequencies. Responses were assessed by EMG activity recorded from tibialis anterior and gastrocnemius muscles of both legs and by changes in center of pressure as measured by a force platform. Results indicated that vibration induced reproducible EMG and postural responses in the anteroposterior direction, particularly on cessation of vibration. EMG and postural responses were considerably lower and less consistent with mastoid vibration compared with neck muscles vibration. Previous reports suggest that vibratory stimulation could propagate to the vestibular organs and generate a vestibular-induced postural activation. However, our findings indicate that cervical muscles afferents play a dominant role over vestibular afferents when vibration is directed towards the neck muscles.

Treatment of phobic postural vertigo

In balance clinic practice, phobic postural vertigo is a term used to define a population with dizziness and avoidance behavior often as a consequence of a vestibular disorder. It has been described as the most common form of dizziness in middle aged patients in dizziness units. Anxiety disorders are common among patients with vestibular disorders. Cognitive-behavioral therapy is an effective treatment for anxiety disorders, and vestibular rehabilitation exercises are effective for vestibular disorders. This study compared the effect of additional cognitive-behavioral therapy for a population with phobic postural vertigo with the effect of self-administered vestibular rehabilitation exercises. 39 patients were recruited from a population referred for otoneurological investigation. Treatment effects were evaluated with the Dizziness Handicap Inventory, Vertigo Symptom Scale, Vertigo Handicap Questionnaire, and Hospital Anxiety and Depression Scale. All patients had a self treatment intervention based on education about the condition and recommendation of self exposure by vestibular rehabilitation exercises. Every second patient included was offered additional cognitive behavioral therapy. Fifteen patients with self treatment and 16 patients with cognitive- behavioral treatment completed the study. There was significantly larger effect in the group who received cognitive behavioral therapy than in the self treatment group in Vertigo Handicap Questionnaire and the Hospital Anxiety and Depression scale and its subscales. Cognitive-behavioral therapy has an additional effect as treatment for a population with phobic postural vertigo. A multidisciplinary approach including medical treatment, cognitive-behavioral therapy and physiotherapy is suggested.

Effects of hypothermic anesthesia of the feet on vibration-induced body sway and adaptation

The aim of this study was to investigate the significance of information from the plantar cutaneous mechanoreceptors in postural control and whether postural control could compensate for reduced cutaneous information by adaptation. Sixteen healthy subjects were tested with eyes open or eyes closed with hypothermic and normal feet temperature during posturography where body sway was induced by vibratory proprioceptive stimulation towards both calf muscles. The hypothermic anesthesia was obtained by cooling the subject's feet in ice water for 20 minutes. Body movements were evaluated by analyzing the anteroposterior and lateral torques induced towards the supporting surface by a force platform during the posturography tests. The reduction of cutaneous sensor information from the mechanoreceptors of the feet significantly increased the vibration-induced torque variance mainly in the anteroposterior direction. However, the effects of disturbed mechanoreceptors information was rapidly compensated for through postural adaptation and torque variance was in level with that without anesthesia within 50 to 100 seconds of stimulation, both when standing with eyes open and eyes closed. Our findings suggest that somatosensory input from mechanoreceptors in the foot soles contribute significantly in maintaining postural control, but the sensory loss could be compensated for.

Effects of hypothermic anesthesia of the feet on vibration-induced body sway and adaptation

The aim of this study was to investigate the significance of information from the plantar cutaneous mechanoreceptors in postural control and whether postural control could compensate for reduced cutaneous information by adaptation. Sixteen healthy subjects were tested with eyes open or eyes closed with hypothermic and normal feet temperature during posturography where body sway was induced by vibratory proprioceptive stimulation towards both calf muscles. The hypothermic anesthesia was obtained by cooling the subject's feet in ice water for 20 minutes. Body movements were evaluated by analyzing the anteroposterior and lateral torques induced towards the supporting surface by a force platform during the posturography tests. The reduction of cutaneous sensor information from the mechanoreceptors of the feet significantly increased the vibration-induced torque variance mainly in the anteroposterior direction. However, the effects of disturbed mechanoreceptors information was rapidly compensated for through postural adaptation and torque variance was in level with that without anesthesia within 50 to 100 seconds of stimulation, both when standing with eyes open and eyes closed. Our findings suggest that somatosensory input from mechanoreceptors in the foot soles contribute significantly in maintaining postural control, but the sensory loss could be compensated for.

Inferior vestibular neuritis

Sudden, spontaneous, unilateral loss of vestibular function without simultaneous hearing loss or brain stem signs is generally attributed to a viral infection involving the vestibular nerve and is called acute vestibular neuritis. The clinical hallmarks of acute vestibular neuritis are vertigo, spontaneous nystagmus, and unilateral loss of lateral semicircular function as shown by impulsive and caloric testing. In some patients with vestibular neuritis the process appears to involve only anterior and lateral semicircular function, and these patients are considered to have selective superior vestibular neuritis. Here we report on two patients with acute vertigo, normal lateral semicircular canal function as shown by both impulsive and caloric testing, but selective loss of posterior semicircular canal function as shown by impulsive testing and of saccular function as shown by vestibular evoked myogenic potential testing. We suggest that these patients had selective inferior vestibular neuritis and that contrary to conventional teaching, in a patient with acute spontaneous vertigo, unilateral loss of lateral semicircular canal function is not essential for a diagnosis of acute vestibular neuritis.

Multi-stimulus multi-response posturography

In this study a method for the analysis of simultaneous multiple measurements of kinematics and stabilizing forces related to human postural dynamics is proposed. Each subject in a group of normal subjects (n=10) was tested with eyes-open and eyes-closed with simultaneous but uncorrelated vestibular and proprioceptive stimuli in order to investigate the contributions of individual sensory feedback loops. Statistical analysis was made by means of multi-input multi-output identification of a transfer function from stimuli to stabilizing forces of the feet and the resulting body position, the transfer function being compatible with a biomechanical model formulated as a stabilized segmented inverted pendulum subject to feedback of body sway and position. Each individual model estimated is effective in predicting a subject's response to new stimuli and in describing the interacting effects of stimuli on body kinetics. The proposed methodology responds to the current needs of data analysis of multi-stimulus multi-response experiments.

Individual semicircular canal function in superior and inferior vestibular neuritis

OBJECTIVE

To examine the concept of selective superior and inferior vestibular nerve involvement in vestibular neuritis by studying the distribution of semicircular canal (SCC) involvement in such patients.

BACKGROUND

Vestibular neuritis was traditionally thought to involve the superior and inferior vestibular nerves. Recent work suggests that in some patients, only the superior nerve is involved. So far there are no reported cases of selective involvement of the inferior vestibular nerve.

METHODS

The authors measured the vestibuloocular reflex from individual SCC at natural head accelerations using the head impulse test. The authors studied 33 patients with acute unilateral peripheral vestibulopathy, including 29 with classic vestibular neuritis and 4 with simultaneous ipsilateral hearing loss, 18 healthy subjects and 15 surgical unilateral vestibular deafferented patients.

RESULTS

In patients with preserved hearing, eight had deficits in all three SCC, suggesting involvement of the superior and inferior vestibular nerves. Twenty-one had a lateral SCC deficit or a combined lateral and anterior SCC deficit consistent with selective involvement of the superior vestibular nerve. Two patients with ipsilateral hearing loss had normal caloric responses and an isolated posterior SCC deficit on impulsive testing. The authors propose that these two patients had a selective loss of inferior vestibular nerve function.

CONCLUSION

Vestibular neuritis can affect the superior and inferior vestibular nerves together or can selectively affect the superior vestibular nerve.

The effects of galvanic stimulation on the human vestibulo-ocular reflex

We studied the effects of 5 mA bilateral or unilateral, bipolar or monopolar, galvanic stimulation on the horizontal vestibulo-ocular reflex (hVOR) in six normal subjects during 0.01, 0.05, 0.1, 0.5 and 1 Hz yaw rotations and in two subjects during high-acceleration, low-amplitude yaw head rotations (head impulses). Bipolar galvanic stimulation induced horizontal nystagmus in all subjects and an asymmetry of the hVOR only during rotations below 0.1 Hz. Monopolar stimulation had no significant effect. The findings suggest that in humans galvanic stimulation affects those primary horizontal semicircular canal neurons that mediate the hVOR via indirect pathways through the velocity storage mechanism.

Neck muscle vibration alters visually-perceived roll after unilateral vestibular loss

Unilateral sternocleidomastoid muscle vibration was applied to 21 normal and six unilateral vestibular deafferented (uVD) human subjects at head erect and during 30 degrees left and right whole body roll-tilt. In normal subjects, neck vibration had no effect upon the settings of a visual bar to subjective visual horizontal (SVH) in any roll-tilt condition. In uVD subjects settings to SVH were significantly altered by neck vibration, with ipsilesional neck vibration increasing the SVH bias at head erect. Further, during contralesional roll-tilt, ipsilesional neck vibration in uVD subjects significantly increased the E-effect. These results suggest that compensation after vestibular loss allows cervical signals to influence visual perception of roll-tilt.

Sudden unilateral hearing loss with simultaneous ipsilateral posterior semicircular canal benign paroxysmal positional vertigo: a variant of vestibulo-cochlear neurolabyrinthitis?

We describe 4 patients who all simultaneously developed a sudden total or partial unilateral sensorineural hearing loss and an unusual acute peripheral vestibulopathy in the same ear characterized by posterior semicircular canal benign paroxysmal positional vertigo with intact lateral semicircular canal function. Two patients also had ipsilateral loss of otolith function. The vertigo resolved in all 4 patients after particle-repositioning maneuvers. The findings of audiometry and vestibular tests indicated that the lesion responsible for this syndrome was probably located within the labyrinth itself rather than within the vestibulocochlear nerve and that it was more likely a viral vestibulocochlear neurolabyrinthitis than a labyrinthine infarction.

Direction of galvanically-induced vestibulo-postural responses during active and passive neck torsion

The direction of a postural response induced by galvanic vestibular stimulation depends on the head and trunk position. The relative importance of afferent information (proprioception) and efferent motor command/corollary discharge is unknown. We studied the direction of body sway evoked by galvanic vestibular stimulation in 9 healthy subjects during active and passive head positioning at 0 degrees frontal position, 35 degrees to the left, and 75 degrees to the right, using a custom-built collar. At 0 degrees and 75 degrees there were no significant differences in sway direction between active and passive head positioning. The galvanic stimulation invoked sway toward the anode, mainly in the inter-aural direction. The sway direction differed significantly between active and passive positioning at 35 degrees to the side (p < 0.05). When the head was actively kept in this position, the body sway was mainly in an inter-aural direction. The sway shifted to a naso-occipital direction when the head was passively positioned at 35 degrees. Our results indicate that the afferent proprioceptive information has the largest influence on the direction of the galvanically-induced postural response, although some dependence on efferent motor commands and non-linear cervical proprioception cannot be ruled out entirely.

What inner ear diseases cause benign paroxysmal positional vertigo?

Benign paroxysmal positional vertigo (BPPV) originating from the posterior semicircular canal (pSCC) is a common vestibular disorder that is easy to diagnose and usually easy to treat. The majority of patients with BPPV have no known inner ear disease; they have "primary" or "idiopathic" BPPV. However, a minority does have objective evidence of an inner ear disease on the same side as the BPPV and this group has "secondary" or "symptomatic" BPPV. Previous publications differ on the prevalence of secondary BPPV and about the types of inner ear diseases capable of causing it. In order to determine what proportion of patients have secondary as opposed to primary BPPV and which inner ear diseases are capable of causing secondary BPPV, we searched our database for the 10-year period from 1988 to 1997 and found a total of 2847 patients with BPPV. Of these, 81 (3%) had definite pSCC-BPPV secondary to an ipsilateral inner ear disease. Sixteen had Menière's disease, 24 had an acute unilateral peripheral vestibulopathy, 12 had a chronic unilateral peripheral vestibulopathy, 21 had chronic bilateral peripheral vestibulopathy and 8 had unilateral sensorineural hearing loss. It seems that any inner ear disease that detaches otoconia and yet does not totally destroy pSCC function can cause BPPV and that a case can be made for audiometry and caloric testing in all patients with BPPV.

Head movement restriction and postural stability in patients with compensated unilateral vestibular loss

OBJECTIVE

To study whether restriction of head-neck movements improves postural performance in patients with compensated unilateral total vestibular loss.

DESIGN

Randomized controlled experimental study.

SETTING

Laboratory for clinical and experimental vestibular testing at a tertiary referral center.

PATIENTS

Fifteen consecutive patients (seven men, eight women, mean age 53 years) at routine follow-up, 6 months after translabyrinthine extirpation of acoustic neurinomas (mean tumor size 13.5mm, range 5 to 25mm). None of the patients had signs or symptoms of central nervous system dysfunction.

INTERVENTION

Posturographic tests comparing patients with and without a semirigid neck collar. Test order was randomized between patients to reduce training effects.

MAIN OUTCOME MEASURE

Posturography measuring velocity and variance of quiet stance and measuring body sway induced by vibration at 60, 80, and 100Hz to the calf muscles. Tests were conducted with eyes open and closed.

RESULTS

In tests with vibration at 100Hz to the calf muscles and with eyes open, body sway velocity was significantly higher when patients were wearing a neck collar. No significant difference was found in any other test.

CONCLUSION

Restricting head-neck movements with a neck collar does not improve postural stability in patients with compensated unilateral total vestibular loss. A tendency toward impaired postural performance leads to the conclusion that it is not appropriate to treat such patients with neck collars to improve their balance.

Passive sustained turning of the head induces asymmetric gain of the vestibulo-ocular reflex in healthy subjects

In order to test the hypothesis of an interaction between neck proprioception and the vestibulo-ocular reflex (VOR), we rotated 16 healthy subjects both facing forward and with their heads passively turned 70 degrees to either side. We found that gain tended to be lower when the subjects were rotated with their heads turned opposite to the direction of rotation compared to when they were rotated in the same direction, but facing forward. Although our findings were not statistically significant, they suggest that there is a measurable interaction between neck proprioception and the VOR in subjects with normal vestibular function. Asymmetric neck muscle proprioceptive signals seem to give rise to asymmetric functioning of the VOR, which, at least in part, could be the pathogenesis of cervical dizziness. If so, this could lead to misinterpretation of vestibular assessments in patients with neck pain who also complain of dizziness.

Effects of different treatments on postural performance in patients with cervical root compression. A randomized prospective study assessing the importance of the neck in postural control

Patients with cervical root compression were used as a "model" to investigate the possible importance of neck disorders and cervical sensory information in postural control. We assessed postural performance with posturography before and after treatment in 71 consecutive patients with MRI-verified cervical root compression without medullary compression. The patients were randomized to surgery (n = 22), physiotherapy (n = 24) or treatment with cervical collars (n = 25). There were no differences in postural performance or pain intensity between the groups before treatment. After treatment, the surgery group manifested significant improved postural performance and reduced neck pain scores, as compared to the two conservative treatment groups, and their postural performance had improved to the same level manifested by healthy controls. The conservative treatment groups manifested no consistent significant changes in postural performance or pain scores. Decreased muscular tension due to reduction of cervical pain after surgery and normalization of cervical proprioception are suggested as possible explanations of the improved postural control.

Asymmetric optokinetic after-nystagmus induced by active or passive sustained head rotations

Asymmetric vestibular function affects optokinetic after-nystagmus (OKAN) in man, but little is known about the involvement of cervical proprioception in the visual-vestibular interaction reflected as OKAN. We studied the effect of asymmetric cervical proprioception induced by active maximal, or passive 70 degrees sustained horizontal head rotations on OKAN in 16 healthy subjects. We evoked optokinetic nystagmus (OKN) by means of a whole-field optokinetic drum rotated at a velocity of 90 degrees/s for 60 s. Following left- and right-beating OKN, we recorded OKAN in complete darkness for 60 s by DC electro-oculography. Both passively and actively sustained head rotations significantly reduced the intensity of OKAN beating in the direction opposite to the head rotation, while OKAN beating in the direction of the head rotation remained unchanged. This resulted in significant asymmetry between OKAN beating in the direction of the head rotation vs. that in the opposite direction. The findings show that in normal subjects neck proprioception converges with visual and vestibular signals and affects subcortical OKN. Asymmetric neck proprioception from neck disorders may be hypothesized to induce dizziness or vertigo in situations where OKN is evoked.

Postural and symptomatic improvement after physiotherapy in patients with dizziness of suspected cervical origin

OBJECTIVE

To assess postural performance in patients with dizziness of suspected cervical origin in whom extracervical causes had been excluded, and to assess the effects of physiotherapy on postural performance and subjective complaints of neck pain and dizziness.

DESIGN

Prospective, randomized, controlled trial.

SETTING

Primary care centers and a tertiary referral center.

PATIENTS AND SUBJECTS

Of 65 referrals, 43 patients were excluded because extracervical etiology was suspected. Of the remaining 22 patients, 17 completed the study (15 women, 2 men, x age 37 yr, range 26-49). The controls were 17 healthy subjects (15 women, 2 men, x age 36 yr, range 25-55).

INTERVENTION

Physiotherapy based on analysis of symptoms and findings, and aimed to reduce cervical discomfort. Patients were randomized either to receive immediate physiotherapy (n = 9), or to wait 2 months, undergo repeat measurements, and then receive physiotherapy (n = 8).

MAIN OUTCOME MEASURES

Posturography, measuring velocity and variance of vibration-induced body sway and variance of galvanically induced body sway. Subjective intensity of neck pain (Visual Analog Scale ratings, 0-100), intensity and frequency of dizziness (subjective score 0-4).

RESULTS

The patients manifested significantly poorer postural performance than did healthy subjects (.05 > p > .0001). Physiotherapy significantly reduced neck pain and intensity and the frequency of dizziness (p < .01), and significantly improved postural performance (.05 > p > .0007).

CONCLUSIONS

Patients with dizziness of suspected cervical origin are characterized by impaired postural performance. Physiotherapy reduces neck pain and dizziness and improves postural performance. Neck disorders should be considered when assessing patients complaining of dizziness, but alternative diagnoses are common.

Dizziness of suspected cervical origin distinguished by posturographic assessment of human postural dynamics

Useful clinical tests are lacking for the controversial entity "cervical vertigo". In earlier studies patients assumed to suffer from cervical vertigo or dizziness manifested disturbed postural control as compared to healthy subjects, but were hard to distinguish from patients with other balance disorders. Using posturography in which stance was perturbed by a vibratory stimulus applied towards the calf muscles, we studied 16 consecutive patients with recent onset of neck pain and concomitant complaints of vertigo or dizziness, but normal findings at otoneurological examination and electronystagmography; 18 patients with recent vestibular neuritis; and 17 healthy subjects. We performed system identification of a model of the control of upright human stance, using the vibratory stimulus as input and the recorded body sway as output. According to values for the three normalized parameters of the transfer function of the model (i.e., swiftness, stiffness, and damping), cervical vertigo patients were distinguished both from healthy subjects (P < 0.001), and from vestibular neuritis patients (P < 0.001). It was also possible to distinguish the vestibular neuritis group from the group of healthy subjects (P < 0.01). The results show disturbed postural control in patients with cervical vertigo to differ from that in patients with recent vestibular neuritis, and indicate posturographic assessment of human posture dynamics to be a possible future tool for use in diagnosing cervical vertigo.

Discrimination of patients with acoustic neuroma and peripheral vestibular lesions with human posture dynamics

A group of normal subjects (n = 17) was compared with groups of patients with a diagnosis of vestibular neuritis (n = 18), and acoustic neuromas (n = 35). Fisher linear discriminant analysis was applied to distinguish clusters of parameters characteristic for each disease. Hence it was possible to distinguish the vestibular neuritis patients from the normal group with statistical significance (p < 0.01). Also the patients with an acoustic neuroma could be distinguished from the normal subjects with statistical significance (p < 0.05).

Impaired postural control in patients with cervico-brachial pain

Dizziness and subjective balance disturbances are common complaints in cervical pain syndromes. We assessed balance function with posturography using vibration-induced and galvanically-induced body sway in consecutive patients (n = 116) with cervico-brachial pain syndrome of more than 3 months' duration. A total of 83% of the patients showed signs of cervical root compression on MRT scans. The incidence of complaints of vertigo was 50%. The patients manifested significantly poorer postural control than sex- and age-matched controls (n = 20). Disorders of the neck should be considered when assessing patients complaining of dizziness, vertigo and balance disturbances.

Discrimination between patients with acoustic neuroma and with peripheral vestibular lesion by human posture dynamics

A group of normal subjects (n = 17) was compared with two groups of patients, either with vestibular neuritis (n = 18) or with acoustic neuroma (n = 35) by means of posturography when stance was perturbed with vibrators attached to the calf muscles. Dynamic control of human posture was quantified by means of system identification, and the characteristic parameters of swiftness, stiffness, and damping of a transfer function from vibration to force platform response were used for further comparison. Fisher linear discriminant analysis was used to distinguish sets of parameters characteristic of each disease. Hence it was possible to distinguish the vestibular neuritis group both from the normal group (p < 0.01), and from the patients with acoustic neuroma (p < 0.001). The normal group was characterized by a different postural performance, with higher swiftness and stability parameters (stiffness, damping) than those of the patient groups. These findings indicate that there are differences in the dynamic control of posture between the two patient categories, which may require the development of differentiated rehabilitation programs.

Delayed onset of ototoxic effects of gentamicin in patients with Meniére's disease

In treatment of Meniére's disease, installations of gentamicin are continued until there are signs of disturbance of vestibular or cochlear function. However, since it has been demonstrated that gentamicin is eliminated slowly from the inner ear, a continuing ototoxic effect may be suspected. The present study aimed to investigate the delay of onset of symptoms of ototoxic effects. Five patients with Meniére's disease and disabling vertigo were treated with intratympanic installation of gentamicin. The patients received two installations at two consecutive days, after which the treatment was abated, although no patient showed any symptoms of affection of the vestibular or cochlear end organs. All patients, however, developed vertigo and nystagmus beating toward the not treated ear within 3 to 5 days after the last installation. At 3 months and 1 year later, the treated ear showed no reaction on bithermal caloric stimulation and all patients had a complete relief of attacks of vertigo but hearing levels were about the same compared to before treatment. The present findings demonstrate a delayed onset of ototoxic effects and it is suggested that gentamicin treatment should not be carried on until symptoms develop. Furthermore, extremely low dose treatment may produce loss of vestibular function with the desired relief of vertigo and with less hazards of affecting the hearing level.

Effects of restrained cervical mobility on voluntary eye movements and postural control

The effects of restrained cervical mobility on pursuit eye movements (PEMS), voluntary saccades and postural control, as measured by posturography, were studied in 11 healthy subjects whose cervical spine movement had been restrained for 5 days by means of a rigid neck-collar. At day 5 mean peak velocity of voluntary saccades at amplitudes of 40 degrees and 60 degrees was significantly reduced, as was mean peak gain of PEMs at a stimulus velocity of 50 degrees/s; the variance of body position in vibration-induced body sway was significantly increased, but there was no difference in variance of galvanically-induced body sway or in velocity of vibration-induced body sway. The results suggest that restriction of cervical movements per se affects voluntary eye movements, a conclusion also consistent with findings in patients with tension headache. Restriction of cervical movement only marginally affects postural control.