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Biomedical subjects

R W Baloh

Publications and source records attributed to R W Baloh.

At least 73 records · Page 4Linked to original sources
PubMed1998

Oculomotor phenotypes in autosomal dominant ataxias.

OBJECTIVE: To quantify the oculomotor features of the common spinocerebellar ataxia (SCA) syndromes. SETTING: University ataxia clinic. PATIENTS: Twenty probands with documented SCA mutations. METHODS: Electro-oculographic recordings of saccadic, smooth pursuit, optokinetic, vestibular, and visual-vestibular eye movements. RESULTS: Distinct phenotype and genotype patterns were identified with modest overlap between patterns. Slowing of saccade peak velocities occurred only in SCA1 and SCA2, being present in 100% of patients with SCA2. Impaired vestibulo-ocular reflex gain occurred with SCA3 only. Patients with SCA6 had prominent deficits in smooth tracking but normal saccade velocities and vestibuloocular reflex gain. CONCLUSIONS: The oculomotor findings are consistent with pure cerebellar involvement in SCA6, pontine involvement in SCA1 and SCA2, and vestibular nerve or nuclei involvement in SCA3. These phenotypes can be useful for clinical diagnosis and for investigating the mechanism of system specificity with the SCA syndromes.

Adult↗
PubMed1998

Static and dynamic posturography in patients with vestibular and cerebellar lesions.

OBJECTIVE: To assess the diagnostic usefulness of posturography in 2 well-defined patient groups with impaired balance. PATIENTS: Ten control subjects, 10 patients with bilateral vestibular loss, and 10 patients with cerebellar atrophy. OUTCOME MEASURES: Amplitude, velocity, and frequency of sway in the anteroposterior and medial-lateral directions on a static platform, on foam, and on a moving platform. RESULTS: Both patient groups consistently had increased sway compared with controls, particularly when standing on foam or on a moving platform with eyes closed. Sway amplitude and velocity were increased about the same amount. The Romberg ratio (sway with eyes closed/sway with eyes open) did not reliably differentiate patients from controls or the 2 patient groups from each other. Some patients with cerebellar atrophy exhibited a characteristic body tremor at about 3 Hz in the anteroposterior direction. CONCLUSIONS: Although sway amplitude and velocity were consistently increased in patients with bilateral vestibular loss and patients with cerebellar atrophy, none of the posturography measurements reliably distinguished the 2 patient groups. The finding of increased frequency of sway in the anteroposterior direction in patients with cerebellar atrophy was of limited value since the tremor was visible at the bedside.

Adult↗
PubMed1998

Motor, cognitive, and behavioral performance following unilateral ventroposterior pallidotomy for Parkinson disease.

OBJECTIVE: To evaluate the effects of ventroposterior pallidotomy on motor disability and on behavior and cognition in patients with medically intractable idiopathic Parkinson disease. DESIGN: Detailed motor testing both while receiving and discontinuing levodopa medication, posturography, and neurocognitive and behavioral assessments were performed before and 3 to 6 months after unilateral ventroposterior pallidotomy. SETTING: University-based movement disorder program. PATIENTS: Thirty-two patients without dementia with medically refractory idiopathic Parkinson disease were studied. MAIN OUTCOME MEASURES: Motor function and disability were measured using the Unified Parkinson's Disease Rating Scale, Hoehn and Yahr stage, and the Schwab and England Activities of Daily Living Scale. Dynamic balance was measured by sway (amplitude and velocity) using the Chattecx Balance System. Detailed cognitive and behavioral assessments were also performed both before and after surgery. RESULTS: Eighty-three percent of patients experienced improvement of their total Unified Parkinson's Disease Rating Scale score at 3 to 6 months after surgery. Significant improvements were also seen in the contralateral Unified Parkinson's Disease Rating Scale motor subscore (78%) as well as in the contralateral Unified Parkinson's Disease Rating Scale total score both during the on and off period (78% and 79%, respectively). The Hoehn and Yahr stage, Schwab and England Activities of Daily Living Scale score, and dynamic balance when standing on foam also improved following unilateral pallidotomy in many patients. Cognitive performance remained relatively unchanged following surgery with the exception of category fluency, which exhibited a modest decline (P < .04). A significant improvement in depression was found on the Beck Depression Inventory. CONCLUSIONS: Ventroposterior pallidotomy significantly improves motor performance and daily level of function in Parkinson disease. Cognition and behavior are not adversely affected in patients without dementia, and a cognitive screening battery is proposed.

Adult↗
PubMed1998

Differentiating between peripheral and central causes of vertigo.

The history usually provides the key information for distinguishing between peripheral and central causes of vertigo. Probably the only central lesion that could masquerade as a peripheral vestibular lesion is cerebellar infarction because vertigo and severe imbalance may be the only presenting features. MRI is indicated in any patient with acute vertigo and profound imbalance suspected to be the result of cerebellar infarct or hemorrhage. Patients with chronic recurrent attacks of vertigo often have normal examination results, including normal vestibular function in between attacks. The duration of attacks is most helpful in distinguishing between central and peripheral causes; vertigo associated with vertebrobasilar insufficiency typically lasts minutes, whereas peripheral inner ear causes of recurrent vertigo typically last hours. Positional vertigo nearly always is a benign condition that can be cured easily at the bedside, but in rare cases it can be a symptom of a central lesion, particularly one near the fourth ventricle. Central positional nystagmus is nearly always purely vertical (either upbeating or downbeating), and there are usually associated neurologic findings.

Acute Disease↗
PubMed1998

Balance disorders in older persons: quantification with posturography.

We measured sway velocity using static and dynamic posturography in a group of young normal subjects and two groups of subjects older than 75 years; one older group considered their balance normal for their age, and the other reported imbalance. The latter group consisted of patients with documented peripheral and central vestibular disorders and patients with dizziness and imbalance of unknown cause. The velocity of sway was higher in older subjects than in younger subjects and in older subjects who reported imbalance than in age-matched controls. The difference was greater with dynamic posturography than with static posturography, but the posturography data provided little information about the cause of the imbalance and did not correlate with the frequency of reported falls.

Accidental Falls↗
PubMed1998

Dizziness: neurological emergencies.

A patient's medical history provides the key information for deciding on the type of dizziness and its likely cause. First, one must separate vestibular from non-vestibular causes of dizziness to determine the focus of the diagnostic work-up. Of the common causes of vertigo, benign positional vertigo can be reliably diagnosed and cured at the bedside. One of the few instances where neuroimaging is required on an emergent basis is for a patient presenting with acute vertigo and profound imbalance likely to be a cerebellar hemorrhage or infarct. Antivertiginous and anti-emetic drugs can provide relief of acute vertigo and nausea, but medications should be rapidly tapered to allow compensation to occur.

Diagnosis, Differential↗
PubMed1998

A prospective study of posturography in normal older people.

OBJECTIVE: To follow posturographic measurements over time in a group of normal older subjects to see if sway increases with aging and if sway is greater in those with deteriorating balance and falls. SUBJECTS: Seventy-two community-dwelling older people (age range 79-91 years), who initially had normal neurological evaluations, were followed with three yearly follow-up examinations. MEASUREMENTS: Amplitude and velocity of sway on static and dynamic posturography, Tinetti gait and balance score, reports of falls. RESULTS: Velocity of sway on dynamic tests increased significantly during the 3 years of follow-up. The percentage increase in sway was about the same in the anterior-posterior and medial-lateral directions and with eyes open and eyes closed. Subjects with low Tinetti scores had higher sway amplitude and velocity, particularly on dynamic tests, but no measure of sway was significantly different in those who reported falls compared with those who did not report falls. CONCLUSIONS: Sway increases in normal subjects over time, and sway is greater in older subjects with deteriorating balance compared with those with normal balance. Sway was not greater in those who fell compared with those who did not fall, probably because falls are highly dependent on individual behavior.

Accidental Falls↗
PubMed1998

Spinocerebellar ataxia type 6 with positional vertigo and acetazolamide responsive episodic ataxia.

The SCA6 mutation, a small expansion of a CAG repeat in a calcium channel gene CACNA1A, was identified in three pedigrees. Point mutations in other parts of the gene CACNA1A were excluded and new clinical features of SCA6 reported--namely, central positional nystagmus and episodic ataxia responsive to acetazolamide. The three allelic disorders, episodic ataxia type 2, familial hemiplegic migraine, and SCA6, have overlapping clinical features.

Acetazolamide↗
PubMed1998

Childhood onset of benign positional vertigo.

Benign positional vertigo (BPV) rarely occurs in children, but we identified three members of a family who developed BPV before age 13 years. All three had migraine headaches and two had spontaneous episodes of vertigo. Vasospasm associated with migraine possibly resulted in ischemic damage to the utricular macule, leading to the development of BPV in these patients.

Age of Onset↗
PubMed1998

Disequilibrium in older people: a prospective study.

OBJECTIVE: To identify the clinical and neuroimaging features in older people with disequilibrium of unknown cause. BACKGROUND: Many older people show a deterioration of balance without an identifiable cause. Whether the disequilibrium is a normal aging phenomenon, the result of yet unidentified neuropathology, or a combination of the two is unknown. METHODS: Twenty-nine patients who complained of disequilibrium (ages 75 to 92) and 29 age- and sex-matched control subjects completed five yearly examinations including history and semiquantitative neurologic examination, activities of daily living, visual acuity, mini-mental status, bedside gait and balance score (Tinetti), Purdue pegboard, and vestibular function testing. Concerns about falling and number of falls were quantified. Subcortical white matter lesions (WML) and frontal atrophy (FA) were graded (blindly), and the ventricular-brain ratio (VBR) was measured from MRIs of the brain. RESULTS: On entry, patients differed from control subjects only in measures of balance, concerns about falling, and falls. Over the 5 years, patients were four times more likely to fall than control subjects. The number of falls was highly correlated with measures of balance (p < 0.001). The VBR as well as the frequency of WML and FA were all significantly (p < 0.001) greater in patients than in control subjects. CONCLUSION: Disequilibrium of unknown cause in older people is associated with frequent falls, concerns about falling, brain atrophy, and WML on MRI. Some cases are probably caused by small-vessel ischemic disease.

Accidental Falls↗
PubMed1997

Familial episodic ataxia: clinical heterogeneity in four families linked to chromosome 19p.

We describe the clinical and oculographic findings in 4 families with episodic ataxia and interictal nystagmus (EA-2) linked to chromosome 19p. Episodes varied from pure ataxia to combinations of symptoms suggesting involvement of the cerebellum, brainstem, and cortex. Some affected individuals exhibited a progressive ataxia syndrome phenotypically indistinguishable from the dominantly inherited spinocerebellar ataxia (SCA) syndromes. About one-half of the affected individuals had migraine headaches and several had episodes typical of basilar migraine. Oculographic findings were localizing to the vestibulocerebellum and posterior vermis. Additional genetic and environmental factors must account for the marked clinical heterogeneity in these families with an abnormal gene on chromosome 19p.

Adolescent↗
PubMed1997

Deficits of gaze stability in multiple axes following unilateral vestibular lesions.

Abnormalities in the vestibulo-ocular reflex (VOR) after unilateral vestibular injury may cause symptomatic gaze instability. We compared five subjects who had unilateral vestibular lesions with normal control subjects. Gaze stability and VOR gain were measured in three axes using scleral magnetic search coils, in light and darkness, testing different planes of rotation (yaw and pitch), types of stimulus (sinusoids from 0.8 to 2.4 Hz, and transient accelerations) and methods of rotation (active and passive). Eye velocity during horizontal tests reached saturation during high-velocity/acceleration ipsilesional rotation. Rapid vertical head movements triggered anomalous torsional rotation of the eyes. Gaze instability was present even during active rotation in the light, resulting in oscillopsia. These abnormal VOR responses are a consequence of saturating nonlinearities, which limit the usefulness of frequency-domain analysis of rotational test data in describing these lesions.

Adaptation, Physiological↗
PubMed1997

Progressive ataxia due to a missense mutation in a calcium-channel gene.

We describe a family with severe progressive cerebellar ataxia involving the trunk, the extremities, and speech. The proband, who has prominent atrophy of the cerebellum, shown by magnetic resonance imaging, was confined to a wheelchair at the age of 44 years. Two sons have episodes of vertigo and ataxia that are not responsive to acetazolamide. Quantitative eye-movement testing showed a consistent pattern of abnormalities localizing to the cerebellum. Genotyping suggested linkage to chromosome 19p, and SSCP showed an aberrant migrating fragment in exon 6 of the calcium-channel gene CACNA1A, which cosegregated with the disease. Sequencing of exon 6 identified a G-->A transposition in one allele, at nucleotide 1152, resulting in a predicted glycine-to-arginine substitution at codon 293. The CAG-repeat expansion associated with spinocerebellar ataxia 6 was not present in any family members. This family is unique in having a non-CAG-repeat mutation that leads to severe progressive ataxia. Since a great deal is known about the function of calcium channels, we speculate on how this missense mutation leads to the combination of clinical symptoms and signs.

Amino Acid Sequence↗
PubMed1997

Spinocerebellar ataxia type 6. Frequency of the mutation and genotype-phenotype correlations.

Spinocerebellar ataxia type 6 (SCA6) is the most recently identified mutation causing autosomal-dominant cerebellar ataxia without retinal degeneration (ADCA). The SCA6 mutation is allelic with episodic ataxia type 2 (EA-2), but the two differ clinically because of the presence of progressive, rather than episodic, ataxia in SCA6. SCA6 accounts for 12% of families with ADCA in an ethnically heterogeneous population of patients. Clinical examination, quantitative eye movement testing, and imaging data show that the brainstem is normal in most patients with SCA6, especially within the first 10 years of symptoms. Most patients show progressive ataxia from the onset, but several patients show an episodic course resembling EA-2. Thus, SCA6 mutations not only account for patients with ADCA I and ADCA III phenotypes but also for some patients presenting with episodic features that are typical for EA-2. Interestingly, a compound heterozygote for the SCA6 expansion manifested an earlier onset and more rapid course than family members with the same larger expanded allele.

Adolescent↗
PubMed1997

Hereditary endotheliopathy with retinopathy, nephropathy, and stroke (HERNS).

We describe a Chinese American family with a hereditary syndrome consisting of retinopathy, nephropathy, and stroke, affecting 11 members spanning three generations. Ophthalmologic evaluations revealed macular edema with capillary dropout and perifoveal microangiopathic telangiectases. Several members had renal abnormalities with proteinuria and hematuria. Initial manifestations were visual impairment and renal dysfunction; neurologic deficits occurred in the third or fourth decade of life. Symptoms included migraine-like headache, psychiatric disturbance, dysarthria, hemiparesis, and apraxia. Neuroimaging consistently demonstrated contrast-enhancing subcortical lesions with surrounding edema. Ultrastructural studies showed distinctive multilaminated vascular basement membranes in the brain and in other tissues, including the kidney, stomach, appendix, omentum, and skin. Genetic analysis ruled out linkage to the CADASIL locus on chromosome 19. Distinct from CADASIL, hereditary endotheliopathy with retinopathy, nephropathy, and stroke (HERNS) is an autosomal dominant multi-infarct syndrome with systemic involvement.

Adult↗
PubMed1997

Clinical-pathologic correlation in a patient with selective loss of hair cells in the vestibular endorgans.

We found a selective loss of vestibular hair cells in a patient followed for more than 10 years with imbalance and oscillopsia due to idiopathic progressive loss of vestibular function. Hearing function and cochlear hair cells were normal. The vestibulo-ocular reflex (VOR) gain at high frequencies was relatively maintained despite marked shortening of the dominant VOR time constant (to less than 500 ms). Ultrastructural examination of remaining hair cells showed mitochondrial abnormalities. The ultrashort VOR time constant probably resulted from changes in firing patterns of the primary afferent nerves due to loss of hair cells and impaired energy metabolism in remaining hair cells.

Adult↗
PubMed1996

Vestibular neuritis: clinical-pathologic correlation.

Postmortem examination of the brain and temporal bones of a patient with well-documented vestibular neuritis showed selective neuronal loss in Scarpa's ganglia on the side with absent caloric response. There was loss of hair cells and an "epithelialization" of the utricular macule and semicircular canal cristae on the deafferented side, and synaptic density in the vestibular nuclei on the deafferented side was decreased compared with that on the normal side. All findings were consistent with an isolated viral infection of Scarpa's ganglia. This is the first description of the effects of chronic deafferentation on the vestibular sensory epithelia and the vestibular nuclei in a human being.

Aged↗