Capturing nystagmus in the emergency room: posterior circulation stroke versus acute vestibular neuritis.

OBJECTIVES: To compare acute nystagmus characteristics of posterior circulation stroke (PCS) and acute vestibular neuritis (AVN) in the emergency room (ER) within 24 h of presentation. METHODS: ER-based video-nystagmography (VNG) was conducted, recording ictal nystagmus in 101 patients with PCS (on imaging) and 104 patients with AVN, diagnosed on accepted clinical and vestibular test criteria. RESULTS: Patients with stroke in the brainstem (38/101, affecting midbrain (n = 7), pons (n = 19), and medulla (n = 12)), cerebellum (31/101), both (15/101) or other locations (17/101) were recruited. Common PCS territories included posterior-inferior-cerebellar-artery (41/101), pontine perforators (18/101), multiple-territories (17/101) and anterior-inferior-cerebellar-artery (7/101). In PCS, 44/101 patients had no spontaneous nystagmus. Remaining PCS patients had primary position horizontal (44/101), vertical (8/101) and torsional (5/101) nystagmus. Horizontal nystagmus was 50% ipsiversive and 50% contraversive in lateralised PCS. Most PCS patients with horizontal nystagmus (28/44) had unidirectional "peripheral-appearing" nystagmus. 32/101 of PCS patients had gaze-evoked nystagmus. AVN affected the superior, inferior or both divisions of the vestibular nerve in 55/104, 4/104 and 45/104. Most (102/104) had primary position horizontal nystagmus; none had gaze-evoked nystagmus. Two inferior VN patients had contraversive torsional-downbeat nystagmus. Horizontal nystagmus with SPV ≥ 5.8 °/s separated AVN from PCS with sensitivity and specificity of 91.2% and 83.0%. Absent nystagmus, gaze-evoked nystagmus, and vertical-torsional nystagmus were highly specific for PCS (100%, 100% and 98.1%). CONCLUSION: Nystagmus is often absent in PCS and always present in AVN. Unidirectional 'peripheral-appearing' horizontal nystagmus can be seen in PCS. ER-based VNG nystagmus assessment could provide useful diagnostic information when separating PCS from AVN.

The Video Head Impulse Test.

In 1988, we introduced impulsive testing of semicircular canal (SCC) function measured with scleral search coils and showed that it could accurately and reliably detect impaired function even of a single lateral canal. Later we showed that it was also possible to test individual vertical canal function in peripheral and also in central vestibular disorders and proposed a physiological mechanism for why this might be so. For the next 20 years, between 1988 and 2008, impulsive testing of individual SCC function could only be accurately done by a few aficionados with the time and money to support scleral search-coil systems-an expensive, complicated and cumbersome, semi-invasive technique that never made the transition from the research lab to the dizzy clinic. Then, in 2009 and 2013, we introduced a video method of testing function of each of the six canals individually. Since 2009, the method has been taken up by most dizzy clinics around the world, with now close to 100 refereed articles in PubMed. In many dizzy clinics around the world, video Head Impulse Testing has supplanted caloric testing as the initial and in some cases the final test of choice in patients with suspected vestibular disorders. Here, we consider seven current, interesting, and controversial aspects of video Head Impulse Testing: (1) introduction to the test; (2) the progress from the head impulse protocol (HIMPs) to the new variant-suppression head impulse protocol (SHIMPs); (3) the physiological basis for head impulse testing; (4) practical aspects and potential pitfalls of video head impulse testing; (5) problems of vestibulo-ocular reflex gain calculations; (6) head impulse testing in central vestibular disorders; and (7) to stay right up-to-date-new clinical disease patterns emerging from video head impulse testing. With thanks and appreciation we dedicate this article to our friend, colleague, and mentor, Dr Bernard Cohen of Mount Sinai Medical School, New York, who since his first article 55 years ago on compensatory eye movements induced by vertical SCC stimulation has become one of the giants of the vestibular world.

Transverse sinus stenting for pseudotumor cerebri: a cost comparison with CSF shunting.

BACKGROUND AND PURPOSE: Transverse sinus venous stent placement has been shown to lower intracranial pressure in patients with venogenic pseudotumor cerebri and to reverse, or at least stabilize, its symptoms and signs. There have been no studies comparing the cost of venous stenting with the time-honored treatment for pseudotumor cerebri-CSF shunting. The purpose of this study was to compare the cost of trasverse sinus stenting versus CSF shunting for the treatment of pseudotumor cerebri. MATERIALS AND METHODS: This work was a retrospective cost analysis of individual resource use in 86 adults who were stented for pseudotumor cerebri during a 12-year period compared with resource use in 110 children who were shunted for hydrocephalus during a 3-year period. RESULTS: There was no significant difference between the cost of inserting an initial venous stent ($13,863 ± 4890) versus inserting an initial CSF shunt ($15,797 ± 5442) (P = .6337) or between inserting an additional venous stent ($9421 ± 69) versus revising a CSF shunt ($10,470 ± 1245) (P = .4996). There were far fewer additional venous stent insertions per patient than there were subsequent CSF shunt revisions; 87% of stents placed required just 1 stent procedure, whereas only 45% of shunts required 1 shunt procedure. The main cause of the cost difference was the need for repeated revisions of the shunts, especially when they became infected-24 instances of a total 143 shunt procedures (16.8%) at an average cost of $84,729, approximately 5 times the cost of an initial shunt insertion. CONCLUSIONS: Venous stenting costs significantly less per 100 procedures than does CSF shunting, due largely to the high cost of treating shunt infections and the need for repeated shunt revisions.

The Pseudotumor Cerebri Syndrome: A Unifying Pathophysiological Concept for Patients with Isolated Intracranial Hypertension with Neither Mass Lesion Nor Ventriculomegaly.

In 1991 we proposed that while the syndrome of isolated intracranial hypertension might have many definite and probable causes, it has nonetheless a single unifying pathophysiological mechanism: namely, impairment of cerebrospinal fluid (CSF) reabsorption. For that reason, we also proposed then that it is best described by a single, unifying, inclusive term, namely, pseudotumor cerebri syndrome. Although it appears that there is, as far as nomenclature is concerned, now international agreement, there is as yet no agreement on pathophysiology and classification. Herein we outline our views on these matters and give our reasons.

Malignant meningitis presenting as pseudotumor cerebri.

Malignant leptomeningitis can present as the clinical syndrome of pseudotumor cerebri due to infiltration of arachnoid villi in the superior sagittal sinus. We show that malignant pachymeningitis can also present with pseudotumor cerebri, likely due to cerebral venous hypertension from transverse sinus compression. We present 3 cases of pseudotumor cerebri due to pachymeningeal or leptomeningeal metastases and discuss the mechanism of intracranial hypertension in such cases, its diagnosis and treatment.

Posterior semicircular canal occlusion for intractable benign positional vertigo: outcome in 55 ears in 53 patients operated upon over 20 years.

OBJECTIVE: To report the outcome of posterior semicircular canal occlusion surgery for intractable benign positional vertigo, regarding vertigo cure rate and hearing and balance outcomes. METHODS: Retrospective review of 53 patients presenting with benign positional vertigo, unresponsive to repositioning manoeuvres, who eventually underwent posterior canal occlusion, over a 20 year period. RESULTS: From 1991 to 2011, 5364 benign positional vertigo patients were treated in our balance disorders clinic; 53 of those who failed to respond to repositioning underwent posterior canal occlusion. All 53 were cured of their benign positional vertigo. Nine suffered some symptomatic permanent hearing loss (>20 dB at low and >25 dB at high frequencies). Ten patients suffered caloric vestibular function deterioration, with mild but permanent subjective imbalance in five; a further 10 patients with no post-operative caloric test changes also had some permanent imbalance. Benign positional vertigo later developed in the operated ear lateral canal in two patients and in the opposite ear posterior canal in eight patients. Two patients needed bilateral sequential posterior canal occlusion. CONCLUSION: Posterior canal occlusion is a highly effective treatment for intractable benign positional vertigo, with what is probably an acceptable risk to hearing and balance: five of six patients will have no hearing problem and nine of 10 no balance problem after surgery.

Tuning characteristics of ocular and cervical vestibular evoked myogenic potentials in intact and dehiscent ears.

Cervical and ocular vestibular evoked myogenic potentials (cVEMPs and oVEMPs) to air-conducted tone bursts (250-2000 Hz) were recorded in 14 patients with superior canal dehiscence (SCD) and 32 healthy controls. For cVEMPs, the most common 'optimal frequency' in control ears (48.2%) was 500 Hz; for oVEMPs, it was 1000 Hz (51.8%). We found a significant interaction between age and frequency, with a shift towards higher-frequency tuning in older subjects. cVEMP and oVEMP tuning in SCD was characterised by a broadening of amplitude and threshold tuning curves. The tendency of cVEMPs to tune to lower frequencies compared to oVEMP was enhanced in SCD. Differences in cVEMP and oVEMP 'optimal frequencies', demonstrated in 57.1% intact ears and 81.3% dehiscent ears, imply differences in the recruitment of hair cells generating these two reflexes. Age-matched oVEMP amplitudes provided excellent separation between SCD and control ears. Although cVEMP amplitudes overlapped between SCD and control ears, better separation was achieved by using a 2-kHz stimulus.

Isolated reversible hypoglossal nerve palsy as the initial manifestation of pre-eclampsia.

Isolated hypoglossal nerve lesions often reflect sinister neoplastic or vascular pathology. Rarely, reversible lesions occur, perhaps via mechanisms similar to Bell's palsy. We report a patient with reversible isolated hypoglossal nerve palsy as the first and predominant early manifestation of pre-eclampsia and speculate on the pathogenesis behind this abnormality.

Transverse sinus stenting for idiopathic intracranial hypertension: a review of 52 patients and of model predictions.

BACKGROUND AND PURPOSE: Transverse sinus stenosis is common in patients with IIH. While the role of transverse sinus stenosis in IIH pathogenesis remains controversial, modeling studies suggest that stent placement within a transverse sinus stenosis with a significant pressure gradient should decrease cerebral venous pressure, improve CSF resorption in the venous system, and thereby reduce intracranial (CSF) pressure, improving the symptoms of IIH and reducing papilledema. We aimed to determine if IIH could be reliably treated by stent placement in transverse sinus stenosis. MATERIALS AND METHODS: We reviewed the clinical, venographic, and intracranial pressure data before and after stent placement in transverse sinus stenosis in 52 of our own patients with IIH unresponsive to maximum acceptable medical treatment, treated since 2001 and followed between 2 months and 9 years. RESULTS: Before stent placement, the mean superior sagittal sinus pressure was 34 mm Hg (462 mm H(2)0) with a mean transverse sinus stenosis gradient of 20 mm Hg. The mean lumbar CSF pressure before stent placement was 322 mm H(2)O. In all 52 patients, stent placement immediately eliminated the TSS pressure gradient, rapidly improved IIH symptoms, and abolished papilledema. In 6 patients, symptom relapse (headache) was associated with increased venous pressure and recurrent stenosis adjacent to the previous stent. In these cases, placement of another stent again removed the transverse sinus stenosis pressure gradient and improved symptoms. Of the 52 patients, 49 have been cured of all IIH symptoms. CONCLUSIONS: These findings indicate a role for transverse sinus stent placement in the management of selected patients with IIH.

Sensory neuropathy as part of the cerebellar ataxia neuropathy vestibular areflexia syndrome.

OBJECTIVE: The syndrome of cerebellar ataxia with bilateral vestibulopathy was delineated in 2004. Sensory neuropathy was mentioned in 3 of the 4 patients described. We aimed to characterize and estimate the frequency of neuropathy in this condition, and determine its typical MRI features. METHODS: Retrospective review of 18 subjects (including 4 from the original description) who met the criteria for bilateral vestibulopathy with cerebellar ataxia. RESULTS: The reported age at onset range was 39-71 years, and symptom duration was 3-38 years. The syndrome was identified in one sibling pair, suggesting that this may be a late-onset recessive disorder, although the other 16 cases were apparently sporadic. All 18 had sensory neuropathy with absent sensory nerve action potentials, although this was not apparent clinically in 2, and the presence of neuropathy was not a selection criterion. In 5, the loss of pinprick sensation was virtually global, mimicking a neuronopathy. However, findings in the other 11 with clinically manifest neuropathy suggested a length-dependent neuropathy. MRI scans showed cerebellar atrophy in 16, involving anterior and dorsal vermis, and hemispheric crus I, while 2 were normal. The inferior vermis and brainstem were spared. CONCLUSIONS: Sensory neuropathy is an integral component of this syndrome. It may result in severe sensory loss, which contributes significantly to the disability. The MRI changes are nonspecific, but, coupled with loss of sensory nerve action potentials, may aid diagnosis. We propose a new name for the condition: cerebellar ataxia with neuropathy and bilateral vestibular areflexia syndrome (CANVAS).

Tumour necrosis factor (TNF) inhibitor therapy in Susac's syndrome.

Susac's syndrome is the clinical triad of encephalopathy, branch retinal artery occlusions and sensorineural hearing loss (Susac 1994) [1]. It occurs predominantly in young females and is believed to be an immune-mediated endotheliopathy of small vessels of the brain, retina and cochlea (Neumayer et al. 2009) [2]. Early, aggressive, and sustained immunosuppressive therapy has been recommended for Susac's syndrome and anecdotal evidence has suggested a therapeutic role for monoclonal antibodies (Rennebohm et al. 2008, Lee and Amezcua 2009) [3,4]. We report a case of Susac's syndrome in which the patient improved immediately after tumour necrosis factor (TNF) inhibition with the monoclonal antibody, infliximab.

Carotid endarterectomy for symptomatic, but "haemodynamically insignificant" carotid stenosis.

OBJECTIVE: Carotid endarterectomy (CEA) guidelines in symptomatic carotid stenosis are based on NASCET and ECST criteria with 70% or greater carotid stenosis as estimated from a catheter angiogram the major indication. This has several problems: (1) lack of reliable correlation between non-invasive imaging and catheter angiography, which has been largely superseded by non-invasive imaging in investigating carotid stenosis; (2) errors inherent in estimating the degree of stenosis from catheter angiography; (3) disregard for the fact that stroke risk also depends on plaque stability, and number of ischaemic events. METHODS: A retrospective review of ischaemic events, imaging results, operative findings, surgical complications and stroke-free follow-up in 31 patients presenting over a 23 year period with TIA/stroke (symptoms lasting > 24 h and/or imaging evidence of infarction) who had 70% or less carotid stenosis (on non-invasive imaging), but nonetheless underwent CEA. RESULTS: Nineteen patients had small strokes, 7 had TIAs and 5 had ocular events; 28 patients had features of unstable plaque on imaging; 19 patients experienced multiple events before CEA. All had haemorrhagic, ruptured plaque at CEA. One patient suffered an intra-operative stroke, only 1 patient suffered a further stroke/TIA (mean follow-up 4.2 years). CONCLUSION: To predict the likelihood of major stroke in symptomatic carotid stenosis and the benefit of CEA, plaque stability and the number of ischaemic events might be as important as an estimate of the degree of stenosis.

Vestibular function after acute vestibular neuritis.

PURPOSE: To review the extent and mechanism of the recovery of vestibular function after sudden, isolated, spontaneous, unilateral loss of most or all peripheral vestibular function - usually called acute vestibular neuritis. METHODS: Critical review of published literature and personal experience. RESULTS: The symptoms and signs of acute vestibular neuritis are vertigo, vomiting, nystagmus with ipsiversive slow-phases, ipsiversive lateropulsion and ocular tilt reaction (the static symptoms) and impairment of vestibulo-ocular reflexes from the ipsilesional semicircular canals on impulsive testing (the dynamic symptoms). Peripheral vestibular function might not improve and while static symptoms invariably resolve, albeit often not totally, dynamic symptoms only improve slightly if at all. CONCLUSIONS: The persistent loss of balance that some patients experience after acute vestibular neuritis can be due to inadequate central compensation or to incomplete peripheral recovery and vestibular rehabilitation has a role in the treatment of both.

The video head impulse test: diagnostic accuracy in peripheral vestibulopathy.

BACKGROUND: The head impulse test (HIT) is a useful bedside test to identify peripheral vestibular deficits. However, such a deficit of the vestibulo-ocular reflex (VOR) may not be diagnosed because corrective saccades cannot always be detected by simple observation. The scleral search coil technique is the gold standard for HIT measurements, but it is not practical for routine testing or for acute patients, because they are required to wear an uncomfortable contact lens. OBJECTIVE: To develop an easy-to-use video HIT system (vHIT) as a clinical tool for identifying peripheral vestibular deficits. To validate the diagnostic accuracy of vHIT by simultaneous measures with video and search coil recordings across healthy subjects and patients with a wide range of previously identified peripheral vestibular deficits. METHODS: Horizontal HIT was recorded simultaneously with vHIT (250 Hz) and search coils (1,000 Hz) in 8 normal subjects, 6 patients with vestibular neuritis, 1 patient after unilateral intratympanic gentamicin, and 1 patient with bilateral gentamicin vestibulotoxicity. RESULTS: Simultaneous video and search coil recordings of eye movements were closely comparable (average concordance correlation coefficient r(c) = 0.930). Mean VOR gains measured with search coils and video were not significantly different in normal (p = 0.107) and patients (p = 0.073). With these groups, the sensitivity and specificity of both the reference and index test were 1.0 (95% confidence interval 0.69-1.0). vHIT measures detected both overt and covert saccades as accurately as coils. CONCLUSIONS: The video head impulse test is equivalent to search coils in identifying peripheral vestibular deficits but easier to use in clinics, even in patients with acute vestibular neuritis.