Rosalyn Davies

Positional down beating nystagmus in 50 patients: cerebellar disorders and possible anterior semicircular canalithiasis

Objectives: To clarify the clinical significance of positional down beat nystagmus (pDBN). Methods: A discussion of the neuro-otological findings in 50 consecutive patients with pDBN. Results: In 38 patients there was evidence of CNS disease (central group) but in 12 there was not (idiopathic group). In the CNS group, presenting symptoms were gait, speech, and autonomic dysfunction whereas in the idiopathic group patients mostly reported positional vertigo. The main neurological and oculomotor signs in the CNS group were explained by cerebellar dysfunction, including 13 patients with multiple system atrophy. In patients with multiple system atrophy with a prominent extrapyramidal component, the presence of pDBN was helpful in the differential diagnosis of atypical parkinsonism. No patient with pDBN had the Arnold-Chiari malformation, a common cause of constant down beat nystagmus (DBN). In the idiopathic group, the pDBN had characteristics which suggested a peripheral labyrinthine disorder: vertigo, adaptation, and habituation. In six patients an additional torsional component was found (concurrently with the pDBN in three). Features unusual for peripheral disorder were: bilateral positive Dix-Hallpike manoeuvre in nine of 12 patients and selective provocation by the straight head-hanging manoeuvre in two Conclusion: It is argued that some patients with idiopathic pDBN have benign paroxysmal positional vertigo (BPPV) with lithiasis of the anterior canal. The torsional component may be weak, because of the predominantly sagittal orientation of the anterior canal, and may not be readily seen clinically. Nystagmus provocation by bilateral Dix-Hallpike and straight head-hanging may be explained by the vertical upwards orientation of the ampullary segment of the anterior canal in the normal upright head position. Such orientation makes right-left specificity with the Dix-Hallpike manoeuvre less important than for posterior canal BPPV. This orientation requires a further downwards movement of the head, often achieved with the straight head-hanging position, to provoke migration of the canaliths. The straight head-hanging manoeuvre should be carried out in all patients with a history of positional vertigo and a negative Dix-Hallpike manoeuvre.

Interference between postural control and mental task performance in patients with vestibular disorder and healthy controls

OBJECTIVES To determine whether interference between postural control and mental task performance in patients with balance system impairment and healthy subjects is due to general capacity limitations, motor control interference, competition for spatial processing resources, or a combination of these. METHOD Postural stability was assessed in 48 patients with vestibular disorder and 24 healthy controls while they were standing with eyes closed on (a) a stable and (b) a moving platform. Mental task performance was measured by accuracy and reaction time on mental tasks, comprising high and low load, spatial and non-spatial tasks. Interference between balancing and performing mental tasks was assessed by comparing baseline (single task) levels of sway and mental task performance with levels while concurrently balancing and carrying out mental tasks. RESULTS As the balancing task increased in difficulty, reaction times on both low load mental tasks grew progressively longer and accuracy on both high load tasks declined in patients and controls. Postural sway was essentially unaffected by mental activity in patients and controls. CONCLUSIONS It is unlikely that dual task interference between balancing and mental activity is due to competition for spatial processing resources, as levels of interference were similar in patients with vestibular disorder and healthy controls, and were also similar for spatial and non-spatial tasks. Moreover, the finding that accuracy declined on the high load tasks when balancing cannot be attributed to motor control interference, as no motor control processing is involved in maintaining accuracy of responses. Therefore, interference between mental activity and postural control can be attributed principally to general capacity limitations, and is hence proportional to the attentional demands of both tasks.

Simulator based rehabilitation in refractory dizziness

Abstract.Patients with chronic vestibular symptoms are common in neurological practice but the most effective treatment remains an open question. The purpose of our study was to conduct a controlled, between–group comparison of patients’ responses to a customised exercise regime (Group C, for customised) versus treatment additionally incorporating simulator based desensitisation exposure (Group S, for simulator) integrating whole–body or visual environment rotators. Forty chronic peripheral vestibular patients who had previously undergone conventional vestibular rehabilitation without notable improvement were randomly assigned into Group C or S. Individuals attended therapy sessions twice weekly for eight weeks and were provided with a customised home programme. Response to treatment was assessed at four–week intervals with dynamic posturography, vestibular time constants, and questionnaires concerning symptoms, symptom–triggers and emotional status. At final assessment posturography and subjective scores had significantly improved for both groups, although Group S showed greater improvement. A statistically significant improvement for visual vertigo symptom scores was noted only for Group S (p < 0.01; total improvement 53.5 %). Anxiety and depression levels significantly decreased for both groups; improvements were significantly correlated particularly to improvements in visual vertigo (SCQ) (p < 0.01; r = 0.53 and r = 0.57, respectively). Significant differences were noted between groups (p = 0.02) for posturography scores. Vestibular time constants showed no notable change in either group. Conclusions: Both groups improved but exposure to simulator motion gave overall better results. These effects were also observed in psychological symptoms and partly relate to simulator effects on visual vertigo symptoms. Visual motion and visuo–vestibular conflict situations should be incorporated in the rehabilitation of patients with refractory dizziness.

Dizziness following head injury: a neuro-otological study.

Dizziness is a frequent and debilitating complication of head injury and accounts for increasing numbers of medico-legal claims. A detailed neuro-otological study was carried out from the records of 100 patients with post-traumatic dizziness to explore the neuro-otological basis of their symptoms: 50 patients presenting for medico-legal purposes (group I) and 50 presenting for management of their vestibular symptoms (group II). The two groups showed a similar sex distribution, a similar range of causes of head injury and similar severity of head injury (72 minor, 24 moderate and 4 severe). Of the 100, 88 showed at least one audio-vestibular abnormality on testing. Vertigo of the benign positional paroxysmal type was the commonest vestibular diagnosis in both groups (61/100), and only 8 patients showed central vestibular abnormalities. Fifty-three patients had audiometric abnormalities attributable to the head injury, the commonest of which was a high-tone sensorineural hearing loss. There was no significant difference in the incidence of any of the abnormalities in the medico-legal group (group I) when compared with the symptom management group (group II). The results provide strong evidence for an organic basis to recurring dizziness after head injury, whether or not a claim for compensation is pending, and emphasise the need for specialist neuro-otological investigation if abnormalities are to be identified and managed correctly.

Vertigo as a migraine trigger

Background: It is reported in some individual patients that vestibular stimuli can trigger migraine attacks. This study used a case-control design to examine systematically the hypothesis that vertigo induced by vestibular stimulation (rotation/caloric testing) can act as a specific migraine trigger. Methods: A total of 123 new patients attending neuro-otology or neurology clinics were studied with questionnaires and physician interview to ascertain migraine history according to International Headache Society criteria. A total of 79 who underwent rotation/caloric vestibular testing (test group) were compared with 44 control patients in whom no such testing was carried out (control group). The principal outcome measure was the occurrence of a migraine attack within 24 hours of exposure to vestibular stimulation. Results: Of those participants with a past history of migraines, 19/39 (49%) of the test group experienced a migraine in the study time window, compared with 1/21 (5%) of the control group. Binary logistic regression analysis confirmed that vestibular testing was associated (p < 0.05) with migraine attacks. Conclusions: The results indicate that induced vertigo can act as a migraine trigger, a finding with implications for the diagnosis of patients with episodic vertigo and migraine headache. While such patients may well have basilar migraine or migrainous vertigo, alternatively, another disorder causing episodic vertigo (e.g., benign paroxysmal positional vertigo or Ménière disease) may be triggering migraine headaches.

Three hundred sixty-degree rotation of the posterior semicircular canal for treatment of benign positional vertigo: A placebo-controlled trial

The canalithiasis hypothesis proposes that benign positional vertigo (BPV) is caused by dislodged otoconia that settle in the posterior semicircular canal (PSC). When head position is changed these particles move within the canal and induce abnormal endolymph flow. To clear the PSC from debris we developed a procedure that consists of a full circle of backward head rotation in the exact plane of the canal. Patients were seated in a three-dimensional motion device that rotated in steps of 110 degrees every 30 seconds. The first part of the study was conducted as an open trial; the second part followed a single-blinded, placebo-controlled design: Forward rotation (placebo) was applied first and backward rotation was applied 1 week later if BPV persisted. All patients were assessed with a symptom diary and, in the controlled trial, also with the Dix-Hallpike maneuver. In the open study 10 of 15 patients became asymptomatic after one treatment session. In the controlled trial all 15 patients remained symptomatic after forward rotation while 10 of 14 undergoing backward rotation were relieved from positional vertigo immediately (p = 0.004). The presence of secondary nystagmus during the procedure indicated a favorable outcome. Our findings provide evidence for the efficacy of canal-clearing procedures that validate the canalithiasis hypothesis of BPV.

Randomized Trial of Supervised Versus Unsupervised Optokinetic Exercise in Persons With Peripheral Vestibular Disorders

Background. Visual vertigo (VV) symptoms improve only when customized vestibular rehabilitation (VR) integrates exposure to optokinetic stimuli (OK). However, equipment is expensive, biweekly sessions are not standard practice, and therapy is often unsupervised. Methods. A controlled, parallel-group comparison was made of patients’ responses to an 8-week customized program incorporating OK training via a full-field visual environment rotator (group OKF) or DVD (an optokinetic disc or drum rotating at 40° or 60° s−1), supervised (group OKS) or unsupervised (group OKU). A total of 60 participants with chronic peripheral vestibular symptoms were randomly allocated to 1 of 3 treatment groups: group OKF (n = 20) or OKS (n = 20), in which participants attended weekly sessions and were prescribed customized home exercises incorporating the DVD, or group OKU (n = 20) who practiced customized exercises and the DVD unsupervised. Treatment response was assessed at baseline and at 8 weeks with dynamic posturography, Functional Gait Assessment (FGA), and questionnaires for symptoms, symptom triggers, and psychological state. Results. No significant between-group differences were present at baseline or at post interventions. All groups showed significant within-group improvements for vestibular (ie, lightheadedness), VV, and autonomic symptoms (P < .05). Posturography and FGA improved significantly for groups OKF and OKS (P ≤ .01) as well as anxiety scores for group OKS (P < .05) and depression for group OKF (P < .05). Migraine significantly affected VV improvement (migraineurs improved more; P = .01). The drop-out rate was 55% for group OKU and 10% for each supervised group (P < .01). Conclusions. The DVD may be an effective and economical method of integrating OK into VR. However, rehabilitation should be supervised for greater compliance and improvements, particularly for postural stability and psychological state.

Deficient auditory interhemispheric transfer in patients with PAX6 mutations

PAX6 mutations are associated with absence/hypoplasia of the anterior commissure and reduction in the callosal area in humans. Both of these structures contain auditory interhemispheric fibers. The aim of this study was to characterize central auditory function in patients with a PAX6 mutation. We conducted central auditory tests (dichotic speech, pattern, and gaps in noise tests) on eight subjects with a PAX6 mutation and eight age‐ and sex‐matched controls. Brain magnetic resonance imaging showed absent/hypoplastic anterior commissure in six and a hypoplastic corpus callosum in three PAX6 subjects. The control group gave normal central auditory tests results. All the PAX6 subjects gave abnormal results in at least two tests that require interhemispheric transfer, and all but one gave normal results in a test not requiring interhemispheric transfer. The left ear scores in the dichotic speech tests was significantly lower in the PAX6 than in the control group. These results are consistent with deficient auditory interhemispheric transfer in patients with a PAX6 mutation, which may be attributable to structural and/or functional abnormalities of the anterior commisure and corpus callosum, although the exact contribution of these two formations to our findings remains unclear. Our unique findings broaden the possible functions of PAX6 to include neurodevelopmental roles in higher order auditory processing. Ann Neurol 2004

The Tullio phenomenon: a neurologically neglected presentation.

The Tullio phenomenon refers to sound-induced disequilibrium or oscillopsia. Patients with this condition frequently present to neurologists, many of whom are unfamiliar with the condition and its diagnostic criteria. Indeed, due to the unusual nature of the symptoms patients are often misdiagnosed as having psychiatric disturbances. Tullio patients describe disequilibrium, auditory and visual symptoms, which are recurrent, brief, and often triggered by loud noises or middle ear pressure changes, e.g. the Valsalva manoeuvre. Many cases are associated with superior semicircular canal dehiscence (SCCD). Early work suggested that the presence of sound-induced torsional eye movements and visual field tilts were consequent upon a utricular-mediated ocular tilt reaction. However, more recent evidence from imaging and oculographic research, as well as data from our patient series indicates that these ocular abnormalities are usually the result of superior semicircular canal stimulation. The clinical history and a focussed examination are often sufficient to make the diagnosis, which can be confirmed with high resolution CT imaging of the temporal bones. In some patients, surgical occlusion or resurfacing of the affected canal can ameliorate symptoms and signs. The aim of this paper is two-fold: Firstly, to review the clinical features of the Tullio phenomenon, and secondly, to highlight our own observations in three cases with a new clinical syndrome consisting of Tullio’s phenomenon with bilateral vestibular failure, a pure horizontal nystagmus in response to sound, and no evidence of canal dehiscence.

Defective auditory interhemispheric transfer in a patient with a PAX6 mutation

Heterozygous PAX6 mutation is associated with an absent or hypoplastic anterior commissure and a reduction in the area of the corpus callosum. The authors found deficient auditory interhemispheric transfer in a 53-year-old woman with a PAX6 mutation who had an absent anterior commissure but normal callosal volume.