PubMed Health⌕ Search

Biomedical subjects

H C Hopf

Publications and source records attributed to H C Hopf.

At least 19 recordsLinked to original sources
PubMed2006

Left-hemispheric dominance for articulation: a prospective study on acute ischaemic dysarthria at different localizations.

Dysarthria is a frequent symptom in cerebral ischaemia. However, speech characteristics of these patients have not previously been investigated in relation to lesion site in a prospective study. We investigated the auditory perceptual features in 62 consecutive patients with dysarthria due to a single, non-space-occupying cerebral infarction confirmed by MRI. Standardized speech samples of all patients were stored within 72 h after stroke onset using a digital tape recorder. Speech samples were assessed independently by two experienced speech therapists, who were unaware of the clinical and neuroradiological findings, using an interval scale ranging from 0 to 6. Separately assessed were features of articulation, phonation, prosody, and the global severity for a total of 31 items. Extracerebellar infarctions (85.5%) were located in the lower motor cortex (14.5%), striatocapsular region (46.8%) and base of the pons (24.2%). Isolated cerebellar infarctions were present in 14.5% of patients. There was a strong correlation between the findings of both examiners, showing identical scores, or only minor differences (<1 on the assessment scale) for 80% of all items. The average severity of dysarthria was 2.9 +/- 1.3. Articulatory abnormalities were the predominant deviation characteristics, affecting in particular the production of consonants. However, phonatory and prosodic abnormalities were also frequently observed speech characteristics. As revealed by factor analysis of speech characteristics the total severity of dysarthria was mainly influenced by the impairment of articulation. Speech parameters describing characteristics of articulation and prosody showed significant side-to-side and area differences, while this effect was lacking for any voice parameter. Left cerebral lesions showed a more severe overall impairment of speech and articulation, independent of lesion topography. Thirty-eight of 62 patients were available for follow-up. Speech evaluation showed normal speech within weeks in 15 out of 38 patients (39.5%). In the other 23 patients overall severity of dysarthria was mild. This is the first prospective study which describes speech characteristics of dysarthria due to acute unilateral cerebral infarctions. We could demonstrate that dysarthria in extracerebellar infarctions was more frequently caused by left-sided lesions and that the severity of dysarthria was more pronounced in left-sided lesions independent from lesion topography. All extracerebellar lesions were located along the course of the cortico-bulbar tract fibres. Compatible with a common pathophysiological basis of dysarthria in these patients, none of the 31 speech items differed significantly between subcortical and brainstem lesions.

Acute Disease↗
PubMed2005

A topodiagnostic investigation on body lateropulsion in medullary infarcts.

Body lateropulsion may occur without signs of vestibular dysfunction and vestibular nucleus involvement. The authors examined 10 such patients with three-dimensional brainstem mapping. Body lateropulsion without limb ataxia reflected an impairment of vestibulospinal postural control caused by a lesion of the descending lateral vestibulospinal tract, whereas body lateropulsion with limb ataxia was probably the consequence of impaired or absent proprioceptive information caused by a lesion of the ascending dorsal spino-cerebellar tract.

Ataxia↗
PubMed2004

Brainstem reflex circuits revisited.

Our current understanding of brainstem reflex physiology comes chiefly from the classic anatomical-functional correlation studies that traced the central circuits underlying brainstem reflexes and establishing reflex abnormalities as markers for specific areas of lesion. These studies nevertheless had the disadvantage of deriving from post-mortem findings in only a few patients. We developed a voxel-based model of the human brainstem designed to import and normalize MRIs, select groups of patients with or without a given dysfunction, compare their MRIs statistically, and construct three-plane maps showing the statistical probability of lesion. Using this method, we studied 180 patients with focal brainstem infarction. All subjects underwent a dedicated MRI study of the brainstem and the whole series of brainstem tests currently used in clinical neurophysiology: early (R1) and late (R2) blink reflex, early (SP1) and late (SP2) masseter inhibitory reflex, and the jaw jerk to chin tapping. Significance levels were highest for R1, SP1 and R2 afferent abnormalities. Patients with abnormalities in all three reflexes had lesions involving the primary sensory neurons in the ventral pons, before the afferents directed to the respective reflex circuits diverge. Patients with an isolated abnormality of R1 and SP1 responses had lesions that involved the ipsilateral dorsal pons, near the fourth ventricle floor, and lay close to each other. The area with the highest probabilities of lesion for the R2-afferent abnormality was in the ipsilateral dorsal-lateral medulla at the inferior olive level. SP2 abnormalities reached a low level of significance, in the same region as R2. Only few patients had a crossed-type abnormality of SP1, SP2 or R2; that of SP1 reached significance in the median pontine tegmentum rostral to the main trigeminal nucleus. Although abnormal in 38 patients, the jaw jerk appeared to have no cluster location. Because our voxel-based model quantitatively compares lesions in patients with or without a given reflex abnormality, it minimizes the risk that the significant areas depict vascular territories rather than common spots within the territory housing the reflex circuit. By analysing statistical data for a large cohort of patients, it also identifies the most frequent lesion location for each response. The finding of multireflex abnormalities reflects damage of the primary afferent neurons; hence it provides no evidence of an intra-axial lesion. The jaw jerk, perhaps the brainstem reflex most widely used in clinical neurophysiology, had no apparent topodiagnostic value, probably because it depends strongly on peripheral variables, including dental occlusion.

Adult↗
PubMed2004

Different short-term modulation of cortical motor output to distal and proximal upper-limb muscles during painful sensory nerve stimulation.

The pattern of upper-limb muscle activation following painful stimulation has not been clarified in detail. We investigated the short-term inhibitory and excitatory effects of painful electrical digital stimulation on the motoneuron pools of distal and proximal upper-limb muscles. Transcranial magnetic stimulation (TMS) was used as test stimulus, and painful digital nerve stimulation as conditioning stimulus for motor evoked potential (MEP) recordings over the abductor digiti minimi (ADM), abductor pollicis brevis (APB), biceps brachii (BB), and deltoid muscles. Inhibition of the conditioned MEP response was most prominent in the distal muscles, whereas BB and deltoid muscles were only weakly inhibited. The mean MEP response over APB decreased with painful cutaneous stimuli, showing maximum inhibition (by 82%) at interstimulus intervals (ISIs) of 50 ms. Inhibition in the ADM was maximal (49%) but less pronounced at an ISI of 40 ms. The BB and deltoid muscles showed inhibition by 25% and 29%, respectively. Significant facilitation was present in BB and deltoid muscles by 43% and 41% at an ISI of 100 ms, but not in the smaller hand muscles. The observed pattern of upper-limb muscle activation corresponds to the protective withdrawal reflex and the neuronal basis of the observed short-term modulation of motor activity is compatible with a spinal or brainstem pathway.

Adult↗
PubMed2004

[Diffusion-weighted MRT in vertebrobasilar ischemia. Application, sensitivity, and prognostic value].

The aim of this study was to evaluate the applicability, sensitivity, and predictive power of diffusion-weighted MR imaging (DWI) in the diagnosis of vertebrobasilar infarction. From 1997 to 2002, we prospectively recruited 268 patients with acute signs and symptoms suspective of vertebrobasilar ischemia. The patients underwent biplanar EPI-T2 and EPI DWI within 24 h after onset of symptoms and high-resolution MRI as a control within 7 days. One hundred twenty-one patients had additional CT scanning. The DWI revealed acute vertebrobasilar infarction in 71.0%. The mean time exposure of DWI was 8 min and thus no more than that of CT imaging. It showed significantly more acute lesions than CT imaging (28.0%), but additional high-resolution MRI was not able to reveal more lesions than DWI alone. Even in 42 patients with reversible brainstem or cerebellar symptoms classified as TIA or PRIND, DWI demonstrated acute ischemia in 42.8%. Sixty-three patients with optimal final diagnosis of vertebrobasilar ischemia had normal DWI. One week after onset of symptoms, 88.9% of these patients had recovered completely or showed minimal symptoms. Therefore, DWI is a sensitive indicator of acute vertebrobasilar ischemia. It is no more time-consuming than CT imaging, and normal DWI is a predictor of good clinical outcome in patients with brainstem or cerebellar infarction.

Adult↗
PubMed2004

Topodiagnostic investigations on the sympathoexcitatory brain stem pathway using a new method of three dimensional brain stem mapping.

OBJECTIVES: To study the incompletely understood sympathoexcitatory pathway through the human brain stem, using a new method of three dimensional brain stem mapping on the basis of digitally postprocessed magnetic resonance imaging (MRI). METHODS: 258 consecutive patients presenting with acute signs of brain stem ischaemia underwent biplane T2 and EPI diffusion weighted MRI, with slice orientation parallel and perpendicular to a transversal slice selection of the stereotactic anatomical atlas of Schaltenbrand and Wahren, 1977. The individual slices were digitally normalised and projected onto the appropriate slices of the anatomical atlas. For correlation analysis lesions were imported into a three dimensional model of the human brain stem. RESULTS: 31 of the 258 patients had Horner's syndrome caused by acute brain stem ischaemia. Only four of the patients with Horner's syndrome had pontine infarctions, 12 had pontomedullary lesions, and 15 had medullary lesions. Correlation analysis showed significantly affected voxels in the dorsolateral medulla but not in the pons. A statistical comparison with infarct topology in patients with medullary lesions but without Horner's syndrome indicated that involvement of the medial and ventral part of affected voxels located in the ventrolateral medullary tegmentum was specific for Horner's syndrome. CONCLUSIONS: Based on this first in vivo topodiagnostic study, the central sympathoexcitatory pathway probably descends through the dorsal pons before converging on specific generators in the ventrolateral medullary tegmentum at a level below the IX and X nerve exits.

Aged↗
PubMed2003

Anxiety disorders and other psychiatric subgroups in patients complaining of dizziness.

Two hundred and two consecutive patients with dizziness were evaluated using blind neuro-otological testing and examination, blind psychiatric examination, including structured interviews (according to DSM-IV), the Symptom Check-List (SCL 90 R), and the State-Trait Anxiety Inventory (STAI). In 28% of the patients (N=50) dizziness was of organic origin (O group); in 55.3% (N=99) of psychogenic origin (P group) and in 16.8% comorbid psychiatric disorders were found (Mixed group). In 5.3% (N=10) neither organic nor psychiatric results could be found, which could explain the dizziness (Ideopathic group). Compared with the Organic group the patients with psychiatric disorders (P and Mixed group) had much more extensive workups for dizziness, intense emotional distress (anxiety, depression), greater handicaps, and high somatization scores. In the P and Mixed groups three main subgroups of psychiatric disorders could be found: anxiety (N=56), depressive (N=20), and somatoform disorders (N=53). Patients with anxiety and depressive disorders showed the greatest emotional distress and handicaps. The results indicate that psychiatric disorders, above all anxiety disorders, should be included in the differential diagnosis in patients with a long duration of dizziness and great handicaps. An interdisciplinary treatment (including psychiatric treatment) would be superior to an exclusive somatic one.

Adolescent↗
PubMed2002

Mutation analysis of the spastin gene (SPG4) in patients in Germany with autosomal dominant hereditary spastic paraplegia.

Hereditary spastic paraplegias (HSP) comprise a genetically and clinically heterogeneous group of neurodegenerative disorders characterized by progressive spasticity and hyperreflexia of the lower limbs. Autosomal dominant hereditary spastic paraplegia 4 linked to chromosome 2p (SPG4) is the most common form of autosomal dominant hereditary spastic paraplegia. It is caused by mutations in the SPG4 gene encoding spastin, a member of the AAA protein family of ATPases. In this study the spastin gene of HSP patients from 161 apparently unrelated families in Germany was analyzed. The authors identified mutations in 27 out of the 161 HSP families; 23 of these mutations have not been described before and only one mutation was found in two families. Among the detected mutations are 14 frameshift, four nonsense, and four missense mutations, one large deletion spanning several exons, as well as four mutations that affect splicing. Most of the novel mutations are located in the conserved AAA cassette-encoding region of the spastin gene. The relative frequency of spastin gene mutations in an unselected group of German HSP patients is approximately 17%. Frameshift mutations account for the majority of SPG4 mutations in this population. The proportion of splice mutations is considerably lower than reported elsewhere.

Adenosine Triphosphatases↗
PubMed2002

Cranial nerve function in workers exposed to polychlorinated dioxins and furans.

OBJECTIVE: To look for possible effects of polychlorinated dioxins and furans (PCDD/F) on cranial nerve function. MATERIAL AND METHODS: Clinical and neurophysiological examinations [visual and brainstem auditory evoked potentials (VEP and BAEP), blink reflex] in 121 PCDD/F exposed workers of one pesticide producing plant. RESULTS: BAEP abnormalities were more frequent in workers with chloracne (6 of 33 workers, 18.2%) than in those without chloracne (7 of 84, 8.3%), but this was not statistically significant (chi2: 2.33). VEP abnormalities were seen in one worker with and two without chloracne. Clinically visual functions were normal except in one worker, who was amaurotic since birth. Blink reflex abnormalities without corresponding clinical findings were observed in two patients without chloracne. CONCLUSION: Severe exposure to PCDD/F is not followed by clinical signs of cranial nerve dysfunction but may create an increased risk for abnormal BAEP findings, which were more than twice as common in workers with chloracne. Although this difference did not reach statistical significance, it cannot exclude a toxic effect of PCDD/F, as statistical significance is difficult to achieve with such small numbers of workers. In none of the workers, BAEP abnormalities were accompanied by clinical signs of hearing dysfunction.

Adult↗
PubMed2002

Diffusion weighted magnetic resonance imaging in the diagnosis of reversible ischaemic deficits of the brainstem.

OBJECTIVES: To evaluate the sensitivity of diffusion weighted magnetic resonance imaging (MRI) for the diagnosis of clinically suspected reversible ischaemic deficits of the brainstem. METHODS: A total of 158 consecutive patients presenting with acute signs of brainstem dysfunction were investigated using EPI diffusion weighted MRI within 24 hours of the onset of symptoms. High resolution T1 and T2 weighted imaging was performed as a follow up after a median of six days. RESULTS: Fourteen of the 158 patients had a complete clinical recovery within 24 hours (transitory ischaemic attack (TIA)), and 19 patients recovered in less than one week (prolonged reversible neurological deficit (RIND)). Diffusion weighted MRI showed acute ischaemic deficits in 39% of patients with transient neurological deficits. The detection rate seemed to be higher in patients with longer lasting symptoms, but the difference between patients with TIA (29%) and RIND (47%) was not significant. CONCLUSIONS: Diffusion weighted MRI is a sensitive indicator of acute ischaemic brainstem deficits even in patients with reversible neurological deficit. Early identification of patients with TIA and increased risk of stroke may influence acute management and improve patient outcome.

Acute Disease↗
PubMed2001

Abduction paresis with rostral pontine and/or mesencephalic lesions: Pseudoabducens palsy and its relation to the so-called posterior internuclear ophthalmoplegia of Lutz.

BACKGROUND: The existence of a prenuclear abduction paresis is still debated. METHODS: In a retrospective design, we identified 22 patients with isolated unilateral (n = 20) or bilateral (n = 2) abduction paresis and electrophysiologic abnormalities indicating rostral pontine and/or mesencephalic lesions. Another 11 patients had unilateral abduction paresis with additional ocular motor abnormalities indicating midbrain dysfunction. Eight of these 11 patients also had electrophysiological abnormalities supporting this location. Electrophysiological examinations in all patients included masseter and blink reflexes (MassR, BlinkR), brainstem auditory evoked potentials (BAEP), and direct current elctro-oculography (EOG). RESULTS: Unilateral MassR abnormalities in patients with unilateral abduction paresis were seen in 17 patients and were almost always (in 16 of 17 patients) on the side of the abduction paresis. Another 11 patients had bilateral MassR abnormalities. BlinkR was always normal. EOG disclosed slowed abduction saccades in the non-paretic eye in 6 patients and slowed saccades to the side opposite to the abduction paresis in another 5 patients. Re-examinations were done in 27 patients showing normalization or improvement of masseter reflex abnormalities in 18 of 20 patients and in all patients with EOG abnormalities. This was always associated with clinical improvement. CONCLUSIONS: Electrophysiologically documented or clinically evident rostral pontine and/or mesencephalic lesions in our patients exclude an infranuclear intrapontine 6th nerve lesion and indicate the existence of an abduction paresis of prenuclear origin. An increased tone of the antagonistic medial rectus muscle during lateral gaze either by abnormal convergence or impaired medial rectus inhibition seems most likely.

Abducens Nerve Diseases↗
PubMed2001

Sensory neuropathy of the trigeminal, glossopharyngeal, and vagal nerves in Sjögren's syndrome.

Isolated cranial nerve involvement in primary Sjögren's syndrome (primary SS) has rarely been described. We report the case of a patient with sensory neuropathy of the trigeminal and also the glossopharyngeal and vagal nerves, which has not been identified previously. The electrophysiological findings in our patient with primary SS confirmed trigeminal sensory neuropathy with abnormal blink reflexes and abnormal cutaneous masseter inhibitory reflexes.

Cranial Nerve Diseases↗
PubMed2001

Dysarthria in acute ischemic stroke: lesion topography, clinicoradiologic correlation, and etiology.

BACKGROUND AND PURPOSE: Although dysarthria is a frequent symptom in cerebral ischemia, there is little information on its anatomic specificity, spectrum of associated clinical characteristics, and etiologic mechanisms. METHODS: An investigation of 68 consecutive patients with sudden onset of dysarthria due to a single infarction confirmed by MRI or CT was conducted. RESULTS: Dysarthria was associated with a classic lacunar stroke syndrome in 52.9% of patients. Isolated dysarthria and dysarthria-central facial and lingual paresis occurred in 2.9% (n = 2) and 10.3% (n = 7), respectively. Dysarthria-clumsy hand syndrome was observed in 11.7% (n = 8) of patients and associated with pure motor hemiparesis and/or ataxic hemiparesis in 27.9% (n = 19). The lesions were due to small-vessel disease in 52.9% (n = 36), to cardioembolism in 11.8% (n = 8), and to large-vessel disease in only 4.4% (n = 3) of cases. Infarctions were located in the lower part of the primary motor cortex (5.9%; n = 4), middle part of the centrum semiovale (23.5%; n = 16), genu and ventral part of the dorsal segment of the internal capsule (8.8%; n = 6), cerebral peduncle (1.5%; n = 1), base of the pons (30.9%; n = 21), and ventral pontomedullary junction (1.5%; n = 1). Isolated cerebellar infarctions affected the rostral paravermal region in the superior cerebellar artery territory. CONCLUSIONS: Extracerebellar infarcts causing dysarthria were located in all patients along the course of the pyramidal tract. This finding correlates with the frequent occurrence of associated pyramidal tract signs in 90.7% (n = 62) of patients. Isolated cerebellar infarcts leading to dysarthria were in all cases located in the territory of the superior cerebellar artery.

Adult↗
PubMed2001

Masseter reflex and blink reflex abnormalities in Chiari II malformation.

Masseter reflex and blink reflex were evaluated in 64 patients with a myelomeningocele and Chiari II malformation. In 46 patients, no brainstem signs or symptoms were present. Brainstem dysfunction related to Chiari II malformation occurred in 18 patients. The masseter reflex was more frequently abnormal in the symptomatic than asymptomatic patients (P = 0.02). Although the blink reflex was similarly affected in the two groups of patients (P > 0.1), it was very sensitive, being abnormal in 83% of symptomatic and 65% of asymptomatic patients. Concomitant abnormality of masseter reflex and the late contralateral blink reflex component (R2c) was almost exclusively found in symptomatic patients and reached the highest significance in separating the two groups (P = 0.002).

Adolescent↗
PubMed2001

Topodiagnostic value of blink reflex R1 changes: a digital postprocessing MRI correlation study.

The aim of the study was to investigate the relation of the blink reflex R1 arc to known anatomical brainstem structures. Acute vascular brainstem lesions as identified by magnetic resonance imaging (MRI) of patients with isolated R1 pathology were superimposed into a stereotactic anatomical atlas using a new method of digital postprocessing. Isolated acute brainstem lesions were documented by diffusion-weighted MRI in 12 of 24 patients with unilateral R1 pathology. The lesions were located in the ipsilateral mid- to lower pons. In three patients only, the lesion had partial contact with the principal sensory nucleus of the trigeminal nerve (PSN) on at least one level. In two patients, the lesion involved the medial longitudinal fasciculus. Most lesions were located medially and ventrally to the PSN on transverse slices. Our results underline the high localizing value of changes in the R1 component of the blink reflex in patients with ipsilateral pontine functional deficits. Although available physiological evidence suggests that the R1 component of the blink reflex traverses an oligosynaptic pathway, this MRI study does not support the view that synaptic transmission in the PSN subserves R1. The reflex arc probably descends more medially and ventrally on its course to the facial nucleus.

Adult↗
PubMed2001

Anatomy of brain-stem white-matter tracts shown by diffusion-weighted imaging.

We acquired high-resolution MRI and anisotropically diffusion-weighted images (DWI) with direction-selective gradients of the brain stem in 20 healthy volunteers, to identify brain-stem structures such as white-matter tracts and nuclei which show diffusion anisotropy. After averaging and superposition of individual cuts, the images were projected onto appropriate plates of the Schaltenbrand and Wahren anatomical atlas. We identified 20 structures--white-matter tracts and some nuclei--with high contrast. The direction of fibres could be determined as areas of increased (parallel to) or decreased diffusion (perpendicular to the gradient). This study may contribute to understanding of the functional anatomy of the brain stem.

Adult↗
PubMed2001

Sensitivity of transcranial magnetic stimulation of cortico-bulbar vs. cortico-spinal tract involvement in Amyotrophic Lateral Sclerosis (ALS).

BACKGROUND: An upper motor neuron (UMN) lesion in amyotrophic lateral sclerosis (ALS) is often difficult to identify because clinical signs may be discrete or masked by severe simultaneous LMN lesions. We compared the diagnostic sensitivity of transcranial magnetic stimulation (TMS) to cranial muscles and limb muscles in the detection of UMN lesions. DESIGN: We investigated corticobulbar and corticospinal tract function to the tongue/orofacial muscles and abductor digiti minimi/tibial anterior muscles with TMS in 51 patients with ALS to compare the diagnostic yield in the detection of UMN dysfunction. An UMN lesion was assumed when the following were found: the peripheral conduction time and amplitude of the M-wave were within the normal range, the response to cortical stimulation was absent, the TMS evoked/M-wave amplitude ratio was reduced, and the central motor conduction time or the interside difference was delayed (> mean+2.5 SD). RESULTS: On the basis of these criteria a UMN lesion to the orofacial muscles was identified in 24 patients (47%), to the tongue in 27 (53%), and to the upper and lower limbs in 13 (25%) and 22 patients (43%), respectively. Combined abnormalities from all sites increased the diagnostic yield to 39 patients (76%). TMS of the limb muscles confirmed a UMN lesion in only 15 (54%) of the 28 patients with clinically confirmed UMN involvement. This number increased to 23 patients (82%) if tongue and orofacial muscles were taken into acount. CONCLUSION: Our results indicate the early and in most cases subclinical corticobulbar tract involvement of the central motor pathways to the orofacial muscles and tongue in ALS. TMS of the tongue and orofacial muscles had a higher sensitivity in identifying UMN lesions than that of the upper and lower limbs.

Adult↗