A novel exaggerated "spino-bulbo-spinal like" reflex of lower brainstem origin.

BACKGROUND: Many different oligosynaptic reflexes are known to originate in the lower brainstem which share phenomenological and neurophysiological similarities. OBJECTIVE: To evaluate and discuss the differences and aberrancies among these reflexes, which are hard to discern clinically using neurophysiological investigations with the help of a case report. METHODS: We describe the clinical and neurophysiological assessment of a young man who had a childhood history of opsoclonus-myoclonus syndrome with residual mild ataxia and myoclonic jerks in the distal extremities presenting with subacute onset total body jerks sensitive to sound and touch (in a limited dermatomal distribution), refractory to medications. RESULTS: Based on clinical characteristics and insights gained from neurophysiological testing we could identify a novel reflex of caudal brainstem origin. CONCLUSIONS: The reflex described is likely an exaggerated normal reflex, likely triggered by a dolichoectatic vertebral arterial compression and shares characteristics of different reflexes known to originate in caudal brainstem, which subserve distinctive roles in human postural control.

Does trans-spinal direct current stimulation modulate the Hoffmann reflexes of healthy individuals? A systematic review and meta-analysisc.

STUDY DESIGN: Systematic review and meta-analysis. OBJECTIVES: To summarize the available evidence regarding the effects of trans-spinal direct current stimulation (tsDCS) on spinal monosynaptic circuit excitability in healthy individuals. SETTING: Applied Neuroscience Laboratory, Brazil. METHODS: Abstract screening was performed independently by two authors for studies found in the following databases: PubMed, CINAHL, PsycINFO, Web of Science, and LILACS. If the authors were unable to agree, a third reviewer was consulted. Randomized clinical trials that reported monosynaptic reflex measures were included. Methodological quality was assessed using the Cochrane tool for assessing the risk of bias, and information extracted about the spinal neurophysiological and stimulation protocols and their results. RESULTS: The initial search identified 538 studies. After applying the inclusion criteria and excluding duplicates, seven crossover studies were included in the risk of bias assessment, and six studies in the meta-analyses. The meta-analysis results did not show any significant differences between anodal (pooled standardized mean difference (SMD) = -0.09, 95% CI = -0.72 to 0.55, p = 0.79, I2 = 67%) or cathodal tsDCS (pooled SMD = 0.28, 95% CI = -0.07 to 0.63, p = 0.11, I2 = 0%) and sham tsDCS for Hoffmann reflex modulation. CONCLUSION: tsDCS did not affect the Hoffmann reflex, as shown in six studies. However, these findings come from studies with selection, performance and detection bias, and further research is needed to examine the effect of this intervention.

Sleep bruxism is related to decreased inhibitory control of trigeminal motoneurons, but not with reticulobulbar system.

Sleep bruxism (SB) is a stereotyped movement disorder characterized by grinding or clenching of the teeth during sleep. We aimed to understand the abnormal networks related to the excitability of masticatory pathways in patients with SB. Eleven patients with SB and age- and gender-matched 20 healthy subjects were prospectively enrolled in our study. The masseter inhibitory reflex (MIR) after electrical stimulation and auditory startle reaction (ASR) were examined. For MIR responses, durations of early and late silent period (SP) were shorter and the degree of suppression of SPs was significantly lower in SB group in comparison to those obtained in healthy subjects. The ASR responses even of the masseter muscle, however, were similar between patients with SB and healthy individuals. Abnormal MIR provides support for the decreased inhibitory control of the central masticatory circuits in SB whereas normal ASR suggests the integrity and normal functioning of brainstem pathways mediating startle reaction. Although the sample size is small, our results are in line with previous findings and suggest an abnormally decreased inhibition in trigeminal motoneurons to masseter muscle rather than reticulobulbar pathways in patients with SB.

Recruitment properties and significance of short latency reflexes in neck and eye muscles evoked by brief lateral head accelerations.

Short lateral head accelerations were applied to investigate the recruitment properties of the reflexes underlying the earliest ocular and cervical electromyographic reflex responses to these disturbances. Components of both reflexes are vestibular dependent and have been termed "ocular vestibular evoked myogenic potentials" and "cervical vestibular evoked myogenic potentials", respectively. Previous investigations using a unilateral vestibular stimulus have indicated that some but not all these vestibular-dependent reflexes show a simple power law relationship to stimulus intensity. In particular, crossed otolith-ocular reflexes showed evidence of an inflection separating two types of behaviour. The present stimulus acts bilaterally, and only the earliest crossed otolith-ocular reflex, previously shown to have a strictly unilateral origin, showed evidence of an inflection. Reflex changes in ocular torsion could, in principle, correct for the changes associated with translation for an elevated eye, but our findings indicated that the responses were consistent with previous reports of tilt-type reflexes. For the neck, both vestibular and segmental (muscle spindle) reflexes were evoked and followed power law relationships, without any clear separation in sensitivity. Our findings are consistent with previous evidence of "tilt-like" reflexes evoked by lateral acceleration and suggest that the departure from a power law occurs as a consequence of a unilateral crossed pathway. For the neck, responses to transients are likely to always consist of both vestibular and non-vestibular (segmental) components. Most of the translation-evoked ocular and cervical reflexes appear to follow power law relationship to stimulus amplitude over a physiological range.

Alliaceous migraines.

OBJECTIVE: To report a migraineur with osmophobia and trigger to garlic and onion aroma. BACKGROUND: While odors serve as a trigger in 70% of migraineurs, alliaceous aromas have been described only rarely. Furthermore, nor has more than one type of alliaceous odor acted as a trigger in the same individual. Neither has migraine with aura been described as precipitated by such aromas. A patient experiencing migraines with aura, triggered almost exclusively by alliaceous aromas, is described. CASE STUDY: 32-year-old woman; 5 years previously felt nasal pruritis upon eating a red onion dip. Shortly thereafter, the mere aroma of raw onions caused a sensation of her throat closing along with an associated panic attack. Over the intervening years, upon exposure to onions and garlic aroma she experienced a fortification spectra and visual entopia, followed by a bipareital, crushing level 10/10 headache, burning eyes and nose, lacrimation, perioral paresthesias, generalized pruritis, nausea, fatigue, sore throat, dysarthria, confusion, dyspnea, palpitations, presyncopal sensations, hand spasms, tongue soreness, neck pain, phonophobia, and photophobia. These would persist for 1 hour after leaving the aroma. She was unresponsive to medication and would wear a surgical mask when out. The patient also experienced chemosensory complaints: dysosmias every few months; phantosmias of food or cleaning products every month for a minute of level 5/10 intensity; pallinosmia of onion or garlic odor for 30 minutes after exposure; and metallic pallinugeusia after eating with metal utensils. RESULTS: Neurological exam normal except for bilateral positive Hoffman reflexes. CHEMOSENSORY TESTING: Quick Smell Identification Test 3/3 and Brief Smell Identification Test 12/12 were normal. Magnetic resonance imaging and computed tomography with and without contrast normal. Allergy skin test was positive for garlic and onion. Nose plug and counter stimulation with peppermint prevented the onset of headaches and associated symptoms. CONCLUSION: This is the first report of migraines with aura triggered by more than one alliaceous compound in the same individual. Possible mechanisms include odor induced, emotional change, vasomotor instability, trigeminal-induced neurogenic inflammation, and allergic response. In alliaceous and odor-induced migraines, a trial of counter stimulation and nose plugs is warranted.

Short-term retention effect of rehabilitation using head position-based electrotactile feedback to the tongue: influence of vestibular loss and old-age.

Our objective was to evaluate whether the severity of vestibular loss and old-age (>65) affect a patient's ability to benefit from training using head-position based, tongue-placed electrotactile feedback. Seventy-one chronic dizzy patients, who had reached a plateau with their conventional rehabilitation, followed six 1-h training sessions during 4 consecutive days (once on days 1 and 4, twice on days 2 and 3). They presented bilateral vestibular areflexia (BVA), bilateral vestibular losses (BVL), unilateral vestibular areflexia or unilateral vestibular losses and were divided into two age-subgroups (≤65 and >65). Posturographic assessments were performed without the device, 4h before and after the training. Patients were tested with eyes opened and eyes closed (EC) on static and dynamic (passively tilting) platforms. The studied posturographic scores improved significantly, especially under test conditions restricting either visual or somatosensory input. This 4-h retention effect was greater in older compared to younger patients and was proportional to the degree of vestibular loss, patients with increased vestibular losses showing greater improvements. In bilateral patients, who constantly fell under dynamic-EC condition at the baseline, the therapy effect was expressed by disappearance of falls in BVL and significant prolongation in time-to-fall in BVA subgroups. Globally, our data showed that short training with head-position based, tongue-placed electrotactile biofeedback improves balance in chronic vestibulopathic patients some 16.74% beyond that achieved with standard balance physiotherapy. Further studies with longer use of this biofeedback are needed to investigate whether this approach could have long-lasting retention effect on balance and quality of life.

Carotid sinus syndrome.

Carotid sinus hypersensitivity was first reported more than 200 years ago. Nevertheless, a complete understanding of this relatively common clinical finding in older patients has proven elusive. There is evidence to support an association between symptoms, particularly syncope, and a hypersensitive response to carotid sinus massage. However, the clinical implication of a high prevalence in asymptomatic healthy older persons is not known. A central degenerative process likely underlies the pathophysiology, but this is as yet unproven. Although selected patients have had symptom improvement with treatment, particularly permanent pacing, there is a dearth of randomized controlled trial data to guide management.

Augmented ocular vestibular evoked myogenic potentials to air-conducted sound in large vestibular aqueduct syndrome.

OBJECTIVE: To demonstrate the value of recording air-conducted ocular Vestibular Evoked Myogenic Potentials (oVEMP) in a patient with bilaterally enlarged vestibular aqueducts. DESIGN: Cervical VEMP and oVEMP were recorded from a patient presenting with bilateral hearing loss and imbalance, attributable to large vestibular aqueduct syndrome. The stimuli were air-conducted tone bursts at octave frequencies from 250 to 2000 Hz. Amplitudes and thresholds were measured and compared with the normal response range of 32 healthy control subjects. RESULTS: oVEMP reflexes demonstrated pathologically increased amplitudes and reduced thresholds for low-frequency tone bursts. Cervical VEMP amplitudes and thresholds were within normal limits for both ears across all frequencies of stimulation. CONCLUSIONS: This study is the first to describe the augmentation of AC oVEMPs in an adult with large vestibular aqueduct syndrome.

Neurological complications in hyperemesis gravidarum.

Hyperemesis gravidarum can impair correct absorption of an adequate amount of thiamine and can cause electrolyte imbalance. This study investigated the neurological complications in a pregnant woman with hyperemesis gravidarum. A 29-year-old pregnant woman was admitted for hyperemesis gravidarum. Besides undernutrition, a neurological examination disclosed weakness with hyporeflexia, ophthalmoparesis, multidirectional nystagmus and optic disks swelling; the patient became rapidly comatose. Brain MRI showed symmetric signal hyperintensity and swelling of periaqueductal area, hypothalamus and mammillary bodies, medial and posterior portions of the thalamus and columns of fornix, consistent with Wernicke encephalopathy (WE). Neurophysiological studies revealed an axonal sensory-motor polyneuropathy, likely due to thiamine deficiency or critical illness polyneuropathy. Sodium and potassium supplementation and parenteral thiamine were administered with improvement of consciousness state in a few days. WE evolved in Korsakoff syndrome. A repeat MRI showed a marked improvement of WE-related alterations and a new hyperintense lesion in the pons, suggestive of central pontine myelinolysis. No sign or symptom due to involvement of the pons was present.

Clinical observational gait analysis to evaluate improvement of balance during gait with vibrotactile biofeedback.

BACKGROUND AND PURPOSE: This study explores the effect of vibrotactile biofeedback on gait in 20 patients with bilateral vestibular areflexia using observational gait analysis to score individual balance. METHODS: A tilt sensor mounted on the head or trunk is used to detect head or body tilt and activates, via a microprocessor, 12 equally distributed vibrators placed around the waist. Two positions of the tilt sensor were evaluated besides no biofeedback in three different gait velocity tasks (slow/fast tandem gait, normal gait on foam) resulting in nine different randomized conditions. Biofeedback activated versus inactivated was compared. Twenty patients (10 males, 10 females, age 39-77 years) with a bilateral vestibular areflexia or severe bilateral vestibular hyporeflexia, severe balance problems and frequent falls participated in this study. RESULTS: Significant improvements in balance during gait were shown in our patients using biofeedback and sensor on the trunk. Only two patients showed a significant individual gait improvement with the biofeedback system, but in the majority of our patients, it increased confidence and a feeling of balance. CONCLUSION: This study indicates the feasibility of vibrotactile biofeedback for vestibular rehabilitation and to improve balance during gait.

Evaluation of the levator ani and pelvic wall muscles in levator ani syndrome.

Chronic pelvic pain is a difficult problem to evaluate and treat. Knowledge of the pelvic floor and pelvic wall muscles may enable the provider to identify levator ani spasm syndrome, a possible cause of chronic pelvic pain.

Prepulse inhibition of the startle response with chronic schizophrenia: a replication study.

Prepulse inhibition (PPI) deficit, the acoustic startle reflex (ASR) and habituation (HAB) impairment are considered to be endophenotypes for schizophrenia. The recent two studies have reported that a PPI deficit was detected in Japanese schizophrenic patients. We replicated that study using larger samples (115 schizophrenic patients and 111 normal controls) than the original study and a method same as original study. A startle response monitoring system was used to deliver acoustic startle stimuli, and to record and score the electromyographic activity of the orbicularis oculi muscle. We evaluated the startle measures of mean magnitude of ASR, HAB, and PPI at prepulse sound pressure intensities of 82dB (PPI82), 86dB (PPI86), and 90dB (PPI90). ASR was significantly different between schizophrenic patients and controls. HAB and all PPI session data from schizophrenic patients were significantly lower than in controls. In addition, we detected significant differences for ASR, HAB and each PPI (82, 86 and 90dB) between schizophrenic patients and controls with the use of multiple regression analysis. The gender and smoking state were not correlated with ASR, HAB or any PPI in multiple regression analysis. In conclusion, we were able to replicate the finding of HAB impairment and PPI deficit in chronic Japanese schizophrenic patients.

Electrical stimulation combined with exercise increase axonal regeneration after peripheral nerve injury.

Although injured peripheral axons are able to regenerate, functional recovery is usually poor after nerve transection. In this study we aim to elucidate the role of neuronal activity, induced by nerve electrical stimulation and by exercise, in promoting axonal regeneration and modulating plasticity in the spinal cord after nerve injury. Four groups of adult rats were subjected to sciatic nerve transection and suture repair. Two groups received electrical stimulation (3 V, 0.1 ms at 20 Hz) for 1 h, immediately after injury (ESa) or during 4 weeks (1 h daily; ESc). A third group (ES+TR) received 1 h electrical stimulation and was submitted to treadmill running during 4 weeks (5 m/min, 2 h daily). A fourth group performed only exercise (TR), whereas an untreated group served as control (C). Nerve conduction, H reflex and algesimetry tests were performed at 1, 3, 5, 7 and 9 weeks after surgery, to assess muscle reinnervation and changes in excitability of spinal cord circuitry. Histological analysis was made at the end of the follow-up. Groups that received acute ES and/or were forced to exercise in the treadmill showed higher levels of muscle reinnervation and increased numbers of regenerated myelinated axons when compared to control animals or animals that received chronic ES. Combining ESa with treadmill training significantly improved muscle reinnervation during the initial phase. The facilitation of the monosynaptic H reflex in the injured limb was reduced in all treated groups, suggesting that the maintenance of activity helps to prevent the development of hyperreflexia.

Spinal reflexes in ankle flexor and extensor muscles after chronic central nervous system lesions and functional electrical stimulation.

OBJECTIVE: Spinal reciprocal inhibitory and excitatory reflexes of ankle extensor and flexor muscles were investigated in ambulatory participants with chronic central nervous system (CNS) lesions causing foot drop as a function of time after lesion and stimulator use. METHODS: Thirty-nine participants with progressive (eg, secondary progressive MS) and 36 with generally nonprogressive (eg, stroke) conditions were studied. The tibialis anterior (TA) and soleus maximum H-reflex/M-wave (Hmax/Mmax) ratios and maximum voluntary contractions (MVC) were measured and compared with those in age-matched control participants. Reciprocal inhibition was measured as a depression of the ongoing electromyographic (EMG) activity produced by antagonist muscle-nerve stimulation. RESULTS: Participants with CNS lesions had significantly higher soleus Hmax/Mmax ratios than control participants, and reduced voluntary modulation of the reflexes occurred in both muscles. Reciprocal inhibition of soleus from common peroneal (CP) nerve stimulation was not significantly different from controls in either group. Inhibition of the TA by tibial nerve stimulation decreased and was eventually replaced by excitation in participants with nonprogressive disorders. No significant change occurred in progressive disorders. Use of a foot drop stimulator increased the TA, but not the soleus MVC overall. H-reflexes only showed small changes. Reciprocal inhibition of the TA increased considerably, while that of the soleus muscle decreased toward control values. CONCLUSIONS: Disorders that produce foot drop also produce reflex changes, some of which only develop over a period of years or even decades. Regular use of a foot drop stimulator strengthens voluntary pathways and changes some reflexes toward control values. Thus, stimulators may provide multiple benefits to people with foot drop.

Abnormalities of the vestibulo-collic reflex are similar in migraineurs with and without vertigo.

The amplitude and habituation of the click-evoked vestibulo-collic reflex (VCR) was found reduced between attacks in migraineurs without complaints of ictal or interictal vertigo or dizziness, compared with healthy subjects. As a next step we recorded VCR in 17 migraine patients (eight with migraine without aura and nine with migraine with aura) who presented ictal migrainous vertigo according to the criteria defined by Neuhauser et al., using a method described previously. Migraineurs with migrainous vertigo have similar VCR abnormalities as patients without vertigo, i.e. a decreased global amplitude and absence of habituation. Potentiation seemed more pronounced in migraineurs with vertigo (7.46 +/- 18.6), but the difference was not significant.

Reduced habituation of trigeminal reflexes in patients with episodic cluster headache during cluster period.

A growing body of evidence supports the pivotal role of the hypothalamus in the pathophysiology of cluster headache (CH). On the basis of animal studies, it has been suggested that a hypothalamic dysfunction can lead to a habituation deficit of brainstem reflex responses, as result of a stress-like condition. Taking into account these findings, we tested the hypothesis that habituation of brainstem reflexes may be impaired in CH patients. The habituation phenomenon of the late components (R2 and R3) of the blink reflex was studied in 27 CH patients during the cluster period, in 22 migraine patients interictally and in 20 control subjects. A significant habituation deficit in the R2 and R3 components was found in CH compared with both controls and migraineurs. The lack of habituation in CH, more pronounced than in migraine, points to abnormal processing of sensory stimuli at the trigeminal level that could be driven by hypothalamic dysfunction during the cluster period.

Exaggerated auditory startle responses in patients with spinal cord injury.

OBJECTIVE: Central nervous system reorganization following spinal cord injury (SCI) may cause functional changes in the motor tracts in patients in whom increased auditory startle responses (ASRs) have been previously reported. We hypothesized that if increased ASRs in patients with incomplete SCI were due to compensatory mechanisms, these changes would be related to severity and/or localization of the lesion. METHODS: We examined ASR characteristics in 29 SCI patients and 14 age-matched healthy volunteers. Fourteen patients had incomplete and 15 complete SCI; 10 patients had cervical and 19 thoracolumbar SCI. Five auditory stimuli were applied binaurally to subjects in a sitting position, with a 5-min interstimulus interval. Surface electromyographic recordings were obtained from orbicularis oculi (OOc), sternocleidomastoid (SCM), biceps brachii (BB), and tibialis anterior (TA) muscles. RESULTS: ASR probability was significantly higher and area-under-the-curve was significantly larger in SCM and BB in patients than in controls. ASR latency was significantly shorter in SCM and BB in patients with cervical than in those with thoracolumbar SCI (p < 0.02), but there were no statistically significant differences between complete and incomplete SCI (p > 0.1). Time span since onset correlated significantly with ASR area in OOc, SCM and BB (p < 0.05). CONCLUSION: The capability of the adult central nervous system to reorganize its circuits over time for improved functionality following injury is probably the key to understanding the increased ASRs in patients with SCI. The exaggeration of the startle reflex is potentially important since it may be useful for augmenting voluntary movement in the clinical rehabilitation of patients with SCI.

Reversed ipsilateral acoustic reflex pattern.

OBJECTIVE: To determine the characteristics and possible origin of reversed ipsilateral acoustic reflex. STUDY DESIGN: Retrospective. SETTING: University hospital. PATIENTS: Sixty-three ears in 52 patients (mean age 37.6 years) with unilateral or bilateral sensorineural hearing loss and 45 age- and sex-matched persons as controls. METHODS: Audiometry and impedance audiometry examinations were studied retrospectively. Hearing test records were investigated, and patients with unilateral or bilateral sensorineural hearing loss were included. Forty-five age- and sex-matched persons served as controls. The ipsilateral and contralateral acoustic reflex patterns of these patients were investigated. Reflex-forming acoustic thresholds and latencies of ipsilateral reversed (positive) reflexes were compared with ipsilateral negative (upward) reflexes. RESULTS: The ipsilateral acoustic reflexes of 18 of 63 ears with sensorineural hearing loss were absent, and the remaining 45 were reversed (positive). A significant difference was found between ipsilateral reversed and ipsilateral negative acoustic reflex thresholds (p < .001) and latencies (p < .001). No statistically significant differences were found between ipsilateral and contralateral negative reflex latencies. CONCLUSIONS: The reversed acoustic reflex pattern is not an artifact but a physiologic event. This reflex does not appear to be related to stapedius or tensor tympani muscle contraction. We believe that the etiology of the reversed reflex is related to the system that contains the tympanic membrane, malleus, and incus and their ligaments but not the middle ear muscles.

Evidence for adaptive plasticity in elderly monaural hearing aid users.

Hearing aids can induce perceptual changes in some elderly listeners but few studies have investigated physiological changes in this population. Loudness discomfort levels and acoustic reflex thresholds were measured in long-term users of a single hearing aid. The results show an asymmetry of +2 to +9 dB between ears in the sound level that (i) causes loudness discomfort and (ii) elicits a reflex contraction of the middle ear muscles. The elevation of the acoustic reflex threshold occurs in the ear with hearing aid experience, irrespective of the ear of stimulation. Therefore, there is evidence of adaptive plasticity and this can be measured at the level of the auditory brainstem.

Urtica ferox neuropathy.

A 21-year-old student developed an acute, symmetrical, predominantly motor polyneuropathy within 48 h of walking through a patch of nettles (Urtica ferox). Two companions had similar but less severe symptoms. Nerve conduction studies demonstrated markedly reduced compound muscle action potentials and prolonged distal motor latencies. Recovery occurred over a period of a few weeks. This case demonstrates that cutaneous exposure to Urtica ferox can cause an acute polyneuropathy and that its stinging hairs contain an unidentified neurotoxin.