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Robert W Baloh

Publications and source records attributed to Robert W Baloh.

At least 37 records · Page 2Linked to original sources
PubMed2005

Internuclear ophthalmoparesis in episodic ataxia type 2.

Two patients sharing a novel mutation of the CACNA1A gene for P/Q calcium channels showed significant slowing of adducting saccades compared with normal subjects or patients with cerebellar disease. Internuclear ophthalmoparesis (INO) was clinically evident in one. While these findings might be specific to this mutation, INO in our patients with episodic ataxia type 2 suggested involvement outside the cerebellum, either in the brain-stem internuclear pathway or at the neuromuscular junction.

Adult↗
PubMed2005

Unbiased quantification of Scarpa's ganglion neurons in aminoglycoside ototoxicity.

While most studies have demonstrated damage to the cochlear and vestibular endorgan as the primary site of aminoglycoside toxicity, the effect on the primary afferent neurons of the vestibular ganglion remains to be determined. This study used the unbiased stereology-optical fractionator method to obtain estimates of the vestibular ganglion neuronal number. Archival temporal bone specimens from seven subjects with a history of gentamicin (n=3) and streptomycin (n=4) aminoglycoside ototoxicity were used. The post-ototoxicity survival time ranged from two months to 8 years, with an average of 2.2 years. Seven archival human temporal bone specimens from age-matched subjects with no history of audiovestibular symptoms or ototoxicity served as controls. Group means were compared using unpaired, two-tailed student's t test. The average vestibular ganglion neuronal number in the aminoglycoside ototoxicity group was 20, 733 neurons (CV=0.073), which was significantly lower (p<0.005) than the average number in the age-matched control group of 24, 902 neurons (CV=0.109). These findings may be consistent with either retrograde degeneration or a direct neurotoxic effect of the aminoglycosides on the vestibular ganglion neuron.

Adolescent↗
PubMed2004

Sudden deafness in vertebrobasilar ischemia: clinical features, vascular topographical patterns and long-term outcome.

BACKGROUND AND PURPOSE: The aim of this study is to document the clinical features and natural history of sudden deafness associated with vertebrobasilar ischemia (VBI) and to describe the vascular topographic patterns of ischemic lesions on brain MRI associated with sudden deafness based on data collected from a prospective acute stroke registry. METHODS: From 364 consecutive cases of VBI diagnosed by clinical features and brain MRI between January 2000 and September 2003, 29 patients were identified as having sudden deafness as a symptom of VBI. RESULTS: In our series, the incidence of sudden deafness following VBI is 8.0% (29/364). Hearing loss occurred unilaterally (n=27) or bilaterally (n=2). All but one had vertigo as an associated symptom. Nine patients (31%) presented with an isolated audiovestibular loss initially and subsequently had delayed neurological deficits. Nearly a half of patients (14/29: 48%) showed cochlear features of hearing loss. Seventeen (81%) of 21 patients who were followed for at least 1 year after onset of sudden deafness had a recovery of hearing partially (n=10) or completely (n=7). The improvement rate of hearing loss in patients with profound hearing loss was significantly lower than that in patients with less than profound hearing loss (40% vs. 89%, P<0.01). In addition to infarction in the territory of anterior inferior cerebellar artery (n=23), cerebellar infarction in the territory of the medial branch of posterior inferior cerebellar artery (n=4) or an isolated brainstem infarction (n=2) was also associated with sudden deafness. CONCLUSION: An isolated sudden deafness with cochlear audiometric features can be the initial presentation of VBI. Sudden deafness due to VBI often has a good outcome. There is topographic heterogeneity of ischemic lesions on brain MRI in patients with sudden deafness due to VBI.

Adult↗
PubMed2004

Sudden deafness with vertigo as a sole manifestation of anterior inferior cerebellar artery infarction.

Sudden deafness without associated neurological symptoms and signs is typically attributed to a viral inflammation of the labyrinth. Although sudden deafness occurs with anterior inferior cerebellar artery (AICA) infarction, the deafness is usually associated with other brainstem or cerebellum signs such as crossed sensory loss, lateral gaze palsy, facial palsy, Horner syndrome or cerebellar dysmetria. An 84-year-old woman suddenly developed right-sided tinnitus, hearing loss, vertigo and vomiting. Audiometry and electronystagmography documented absent auditory and vestibular function on the right side. T2-weighted and diffusion-weighted MRI showed a tiny infarct in the right lateral inferior pontine tegmentum. AICA occlusion can cause sudden deafness and vertigo without brainstem or cerebellar signs.

Acute Disease↗
PubMed2004

Mutations in a human ROBO gene disrupt hindbrain axon pathway crossing and morphogenesis.

The mechanisms controlling axon guidance are of fundamental importance in understanding brain development. Growing corticospinal and somatosensory axons cross the midline in the medulla to reach their targets and thus form the basis of contralateral motor control and sensory input. The motor and sensory projections appeared uncrossed in patients with horizontal gaze palsy with progressive scoliosis (HGPPS). In patients affected with HGPPS, we identified mutations in the ROBO3 gene, which shares homology with roundabout genes important in axon guidance in developing Drosophila, zebrafish, and mouse. Like its murine homolog Rig1/Robo3, but unlike other Robo proteins, ROBO3 is required for hindbrain axon midline crossing.

Adult↗
PubMed2004

No mutations in CACNA1A and ATP1A2 in probands with common types of migraine.

BACKGROUND: Mutations in CACNA1A, encoding a neuronal calcium channel subunit, and ATP1A2, encoding a catalytic subunit of a sodium-potassium-ATPase, have been found in some families with dominantly inherited hemiplegic migraine. OBJECTIVE: To determine the prevalence of mutations in these genes in individuals with different migraine syndromes. DESIGN: Prospective screening study. SETTING: University outpatient neurology clinic. Subjects Probands of 19 families with hemiplegic migraine, 7 with basilar migraine, 25 with migraine without aura, and 18 with migraine with aura, as well as 40 unaffected relatives of probands. INTERVENTIONS: All known exons and flanking introns of CACNA1A and ATP1A2 were subjected to denaturing high-performance liquid chromatography analysis of polymerase chain reaction-amplified genomic DNA. Exons with atypical elution patterns were sequenced by standard techniques. MAIN OUTCOME MEASURES: Presence of mutations in CACNA1A and ATP1A2. RESULTS: A single mutation (T666M) was found in CACNA1A in a patient with hemiplegic migraine and ataxia. No other mutation was identified in either gene. The frequency of a previously reported intronic insertion in ATP1A2 was not significantly different between patients with migraine and control subjects. CONCLUSION: These 2 genes are not associated with more common migraine syndromes and are not the most common hemiplegic migraine genes.

Adolescent↗
PubMed2004

A novel mutation in KCNA1 causes episodic ataxia without myokymia.

We describe a unique family in which several individual are affected with episodes of ataxia that best fit the phenotype of episodic ataxia type 2 (EA2). All of the affected family members had episodes typically lasting for several hours, and none of them had muscle abnormalities including myokymia. Episodic ataxia type 1 (EA1) was not considered initially as a clinical diagnosis for the affected individuals in this family. However, by linkage mapping, sequencing and polymorphism analysis, all affecteds were found to have a novel mutation in KCNA1. Numerous missense mutations have been described previously in KCNA1 that cause EA1. The mutation c.1025G>T replaces a highly conserved serine with isoleucine at position 342 (p.Ser342Ile) in the highly conserved fifth transmembrane domain of the KCNA1. This mutation leads to a distinct clinical phenotype without myokymia broadening the scope of clinical characteristics of EA1 and highlighting the heterogeneity of phenotypic effects from distinct missense mutations.

Adult↗
PubMed2004

Genes and migraine.

Migraine is not a disease but a syndrome that undoubtedly has multiple causes. Several migraine syndromes have a clear autosomal dominant pattern of inheritance, and recently, mutations have been found in two different genes in families with hemiplegic migraine. Familial aggregation and twin studies in families with other more common migraine syndromes (i.e., migraine without aura and migraine with aura) show that genetic factors are important, although the mode of inheritance is not always clear. Numerous candidate genes have been identified based on clinical features of migraine and the known functions of the different genes. Recently genome-wide scans in families with migraine without aura and migraine with aura have identified susceptibility loci for these common syndromes. However, none of the numerous studies performed to date provide convincing evidence for a gene responsible for the common varieties of migraine.

Genetic Predisposition to Disease↗
PubMed2003

Immunolocalization of voltage-gated calcium channel alpha1 subunits in the chinchilla cochlea.

The immunohistochemical localization of alpha1A, alpha1B, alpha1C, alpha1D, and alpha1E voltage-gated calcium channel subunits was investigated in the chinchilla organ of Corti and spiral ganglia with the use of specific antipeptide antibodies. The inner and outer hair cells were immunoreactive for alpha1A and alpha1D subunit antibodies. Alpha1C immunoreactivity localized to the nerve terminals innervating inner hair cells and the basal pole of the outer hair cell. There was only non-specific staining to alpha1B and alpha1E. Supporting cells were non-immunoreactive. Spiral ganglia neurons were alpha1B, alpha1C, and alpha1D immunoreactive. A few spiral ganglia neurons were alpha1E immunoreactive. The importance of alpha1D, the pore-forming subunit of the L-type channel, in outer and inner hair cell function has been clearly demonstrated in electrophysiological, molecular biological, and knockout models. The presence of alpha1A, the pore-forming subunit of the P/Q type channels, has not previously been demonstrated in inner and outer hair cells, and its function in the cochlear hair cell is unknown.

Animals↗
PubMed2003

Canavan's leukodystrophy is associated with defects in cochlear neurodevelopment and deafness.

The authors present the temporal bone histopathology of two siblings (4 months old and 6 months old at autopsy) with Canavan's disease, an autosomal recessive leukodystrophy that is variably associated with sensorineural hearing loss. The histopathology demonstrated bilateral absence of the organ of Corti throughout the apical and basal cochlea and mild secondary atrophy of the spiral ganglia neurons. The vestibular end organs and ganglia were normal. These findings implicate a role of aminoacylase II in the neurodevelopment of the organ of Corti.

Atrophy↗
PubMed2003

Hearing symptoms in migrainous infarction.

BACKGROUND: In case reports, migraine headaches have been associated with fluctuating low-frequency hearing loss and sudden, unilateral hearing loss. Auditory symptoms associated with migrainous infarction have not previously been emphasized. OBJECTIVE: To describe migrainous infarction presenting with acute auditory symptoms. DESIGN: Case reports. SETTING: Tertiary care hospitals. PATIENTS: A 40-year-old man with a history of migraine suddenly developed bilateral hearing loss associated with severe, throbbing, occipital headache, tinnitus, vertigo, speech disturbance, and right hemiparesis. An early audiogram showed profound, down-sloping, sensorineural-type hearing loss bilaterally. Sixteen days later, a follow-up pure tone audiogram documented marked improvement in both sides to a pure tone average of 30 dB. Right hemiparesis and dysarthria also improved steadily for 2 months. A 25-year-old woman with a history of migraine with aura suddenly developed hyperacusis, unilateral hearing loss, and migraine headache early in migrainous infarction. Magnetic resonance imaging documented infarcts in the pons and cerebellum. CONCLUSIONS: In these patients, acute auditory symptoms are a part of the prodrome of migrainous infarction. We speculate that these symptoms may have resulted from migraine-associated vasospasm. Migrainous infarction should be considered in the differential diagnosis of acute auditory symptoms, including sudden, bilateral hearing loss.

Acute Disease↗
PubMed2003

Drop attacks and vertigo secondary to a non-meniere otologic cause.

BACKGROUND: Tumarkin falls are sudden drop-attack falls that occur in a subset of patients with Meniere syndrome (endolymphatic hydrops), an inner ear disorder characterized by vertigo spells and hearing loss. OBJECTIVE: To describe the clinical features and quantitative audiovestibular testing results in a case series of patients with Tumarkin falls, episodic vertigo, and normal hearing. SETTING: University referral center for disorders of balance and hearing. METHODS: Case series (unselected) of all patients with Tumarkin falls and a normal audiogram at least 1 year after onset of vestibular symptoms (n = 6) from a retrospective analysis of the records of all patients with Tumarkin falls presenting to Neurotology Clinic at UCLA Medical Center, Los Angeles, Calif, from October 1, 1975, to February 1, 2001 (N = 55). Quantitative audiologic and vestibular function testing, neurologic history, and examination were performed. RESULTS: Five of 6 patients had unilateral caloric paresis, and 1 had bilateral vestibulopathy. Five of 6 had a personal and/or family history of migraine headaches meeting International Headache Society criteria. All patients had a subjective sensation of feeling pushed by an external force, and half of the patients had a subjective tilt of the environment concurrent with the fall. CONCLUSIONS: The incidence of migraine is high in this subgroup of patients with Tumarkin falls and normal hearing. The clinical description of the falls is similar to those associated with Meniere syndrome. Further studies are needed to understand the etiology of Tumarkin falls in these patients with normal hearing.

Adult↗
PubMed2003

A longitudinal study of gait and balance dysfunction in normal older people.

OBJECTIVE: To identify the causes of deteriorating gait and balance in normal older people. METHODS: We measured visual acuity, vestibulo-ocular responses, pure-tone hearing levels, vibration sense, deep tendon reflexes, and Tinetti gait and balance scores in 59 normal older subjects (mean +/- SD age on entry, 78.5 +/- 3.7 years) followed up at yearly examinations (range, 8-10 years). White matter hyperintensities on magnetic resonance imaging taken in mid follow-up were graded qualitatively and quantitatively. RESULTS: For each variable except white matter hyperintensities, we calculated a normalized change per year. There was a significant (P<.05) age-related decrease in vestibulo-ocular reflex gain at 0.05 and 0.20 Hz but not at 0.80 Hz, an increase in pure-tone hearing thresholds (at 1, 2, 4, and 8 kHz), a decrease in vibration sense and deep tendon reflexes in the feet, and a decrease in total Tinetti score. However, only changes in vibration sense in the feet and hearing at 1 kHz were significantly correlated (Spearman rank correlation) with the change in Tinetti score. White matter hyperintensities on magnetic resonance imaging had a higher correlation with the yearly change in Tinetti scores. CONCLUSIONS: This longitudinal study showed age-related decreases in vestibular, visual, auditory, and somatosensation in normal older people, but these changes were only weakly correlated with changes in gait and balance. White matter hyperintensities on magnetic resonance imaging were more highly correlated with changes in gait and balance, but all variables together accounted for only about 29% of the measured change in gait and balance.

Aged↗
PubMed2003

Unbiased stereologic type I and type II hair cell counts in human utricular macula.

OBJECTIVE: The objective of the study was to obtain unbiased estimates of the total number of type I and type II hair cells in human utricular macula from individuals with documented normal vestibular function. STUDY DESIGN: Application of unbiased stereology using microdissected human temporal bone specimens was conducted in an observational study. METHODS: Postmortem temporal bones were obtained from 10 normal patients (age range, 42-96 y; mean age, 82 y). The utricular maculae were microdissected, embedded in plastic, and cut into serial 2-microm sections. Unbiased estimates of the total number of type I and type II hair cells were obtained using the physical fractionator technique of stereology. RESULTS: The average total number of hair cells was 27,508 (CV = 11%) consisting of 17,326 (coefficient of variation [CV] = 11%) type I hair cells and 10,182 (CV = 13%) type II hair cells. The ratio of type I to type II hair cells was 1.70:1. In the age range of the study, there was no statistically significant correlation between hair cell counts and age. CONCLUSIONS: Morphometric studies of the human utricular sensory epithelium can be accomplished using unbiased stereology on microdissected specimens. There was no effect of age on total hair cell counts or on the ratio of type I to type II hair cells in the age range of the study. Further studies on younger subjects are needed to establish the effect of age. The results from the present study are closely aligned with prior studies that estimated total hair cell counts using surface mount preparations. The current data represent the first total type I and type II hair cell counts in human utricular neuroepithelium.

Adult↗