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Biomedical subjects

H J Freund

Publications and source records attributed to H J Freund.

At least 109 records · Page 6Linked to original sources
PubMed1993

The role of premotor cortex and the supplementary motor area in the temporal control of movement in man.

In the present study temporal control of movement was systematically analysed in patients with unilateral lesions of the lateral or medial premotor cortex (PMC) or supplementary motor area (SMA) and in age-matched controls. The ability to learn new temporal adjustments was evaluated by examining rhythm reproduction using either the left or right hand or both hands in an alternating manner. A severe impairment in rhythm reproduction was found after lateral or medial PMC lesions; the deficit was most pronounced when our patients were required to use both hands in an alternating manner. The impairment occurred in the absence of difficulties in manual dexterity or impairments in discriminating the rhythm patterns. In a second series of experiments the contribution of the SMA in organizing movements in the time domain was examined. In this series, two patients with left-sided lesions, including the SMA but sparing tissue from the lateral hemispheric surface, and seven age-matched controls were requested to reproduce rhythm constellations in the presence of a sound signal and from memory. Results reveal that patients with left medial lesions involving the SMA had most severe difficulties to produce any rhythms from memory, though they were able to produce the rhythms under auditory pacing. This deficit in programming sequential patterns from memory in the time domain should be interpreted in the context of a decline in the ability to benefit from previous stimulus presentation, which prevents an effective later programming of these sequences when they have to be rehearsed from memory. It was found that patients with left SMA lesions had an increase in reaction time on a sequential digit task when sequences had to be produced under delayed conditions; by contrast, the controls showed a decrease of reaction time after previous stimulus presentation. The present findings extend previous knowledge on sequential motor tasks and argue for a critical role for both the SMA and the premotor cortex in the generation of sequences from memory that fit into a precise timing plan.

Adult↗
PubMed1993

Motor impairment in Wilson's disease, I: Slowness of voluntary limb movements.

Twenty-three patients with Wilson's disease (WD) treated with D-penicillamine underwent clinical examination, as well as laboratory and motor testing. The clinical findings were scored. Laboratory tests included determination of the caeruloplasmin level, the free serum copper level, 24 h urinary copper excretion, liver enzymes and in 10 patients liver copper content of a liver biopsy. Laboratory tests and clinical scores were correlated. To quantify impairment of voluntary movements in WD fastest possible isometric index finger extensions and fastest alternating finger movements were analysed. Eleven patients presented with abnormally slow and 15 with abnormally irregular voluntary movements. Slowness of alternating movements correlated with the clinical score. The clinical score also correlated with the duration of symptoms prior to onset of therapy. Motor testing turned out to be sensitive enough to monitor improvement of neurological symptoms after onset of therapy. Comparison with motor testing in other basal ganglia diseases and cerebellar patients showed differences to patients with Parkinson's and Huntington's disease and similarities to patients suffering from AIDS-related dementia. In a small number of WD-patients similar results as in patients with a degenerative cerebellar disease were found.

Adolescent↗
PubMed1993

Motor impairment in Wilson's disease, II: Slowness of speech.

The maximal syllable production rate (MSPR) and the ability to reproduce a given target frequency in the 1 to 8 Hz range by repeating the short syllable "ta" was tested in 20 patients with Wilson's disease (WD) and 20 normal subjects. MSPR was significantly reduced in the WD-patients. In the 1 to 5 Hz range normal subjects as well as WD-patients tended to produce slightly higher frequencies than the target frequencies. This hastening was maximal in normals between 4 to 5 Hz whereas in the WD-patients hastening mainly occurred between 3 to 4 Hz. The test results showed a considerable variation across the patients. This variation can be interpreted on the basis of the theory of coupled oscillators. Comparison of speech and finger movements revealed a highly significant correlation between MSPR and the highest possible frequency of voluntary alternating index finger movements. As an application of the presented test treatment effects on speech movements were demonstrated.

Adolescent↗
PubMed1992

Impairment of temporal organization of speech in basal ganglia diseases.

Absolute and relative speech timing were examined in patients suffering from Parkinson's, Huntington's, and Wilson's disease. The task was to speak a standard sentence 10 times, first slowly, and then successively faster up to maximum rate. All patient groups had low maximal speech rates and showed decreased variability of speech rate. The duration of pauses between words was the same as in normals and the relative time structure of the test sentence was basically preserved. For comparison, two cases with nonfluent aphasia had even slower speech rates, large increases in pause duration, and major changes in relative speech timing. The results show the same type of alterations of the temporal organization of speech as those characteristic for rapid alternating limb movements in such patients. They support the view that the speech and skeletomotor systems share common neural control modes despite fundamental biomechanical differences. The common denominator between the speech and the skeletomotor disturbances in basal ganglia diseases may be the undamping and slowing of a fast central oscillator.

Adult↗
PubMed1992

Individual integration of positron emission tomography and high-resolution magnetic resonance imaging.

We have developed, validated, and employed a technique of retrospective spatial alignment and integrated display of positron emission tomographic (PET) and high-resolution magnetic resonance (MR) brain images. The method was designed to improve the anatomical evaluation of functional images obtained from single subjects. In the first computational step, alignment of PET and MR data sets is achieved by iteratively matching in three orthogonal views the outermost scalp contours derived from front-to-back projections of each data set. This procedure avoids true three-dimensional modeling, runs without user interaction, and tolerates missing parts of the head circumference in the image volume, as usually the case with PET. Thereafter, high-resolution MR sections corresponding to the PET slices are reconstructed from the spatially transformed MR data. In a phantom study of this method, PET/MR alignment of the phantom's surface was accurate with average residual misfits of 2.17 to 2.32 mm as determined in three orthogonal planes. In-plane alignment of the phantom's insertion holes was accurate with an average residual misfit of 2.30 mm. In vivo application in six subjects allowed the individual anatomical localization of regional CBF (rCBF) responses obtained during unilateral manual exploration. In each subject, the maxima of the rCBF activations in the hand area were precisely allocated to gray matter in the anterior or posterior wall of the central sulcus. The configuration of the rCBF responses closely followed the gyral structures. The technique provided a better topographical understanding of rCBF changes in subtraction images of PET activation studies. It opens the perspective for studies of structural-functional relationships in individual subjects.

Brain↗
PubMed1992

Oscillatory activity in different motor subsystems in palatal myoclonus. A case report.

In a patient with palatal myoclonus the mutual interaction between voluntary movements and the myoclonic activity was analysed. Amplitude and frequency of myoclonic activity in hand muscles were modulated by flexions and extensions. A 1:1 relationship was found between EMG-bursts in hand muscles and palatal movements. A 1:2 relationship was found between eye and finger movements. Resetting of myoclonus in the abductor digiti minimi muscle occurred after cutaneous ulnar nerve stimulation. It is suggested that feedback plays an important role in the generation of the oscillatory activity in PM in addition to pacemaker activity in brainstem neurons.

Aged↗
PubMed1992

Neurological risk profile in organic erectile impotence.

Thirty men who presented with erectile impotence to the urological department underwent a thorough urological, angiological, and neurological examination with complementary neurophysiological tests of somatosensory and sympathetic and parasympathetic function. Most had vascular and neurological abnormalities. Clinical findings and electrophysiological tests for autonomic dysfunction had the highest yield of abnormal results. Nerve conduction studies and pudendal nerve somatosensory evoked potentials were far less informative. The lack of correlation between vascular and general neurological abnormalities emphasises that patients must be screened for both vascular and neurological dysfunction to prevent unrewarding vascular operation in impotent men.

Adult↗
PubMed1992

Improvement of motor performance of HIV-positive patients under AZT therapy.

We performed motor tests (most rapid alternating movements [MRAMs] of index fingers and most rapid contractions [MRCs] of voluntary isometric index finger extensions) in HIV-positive patients with (group 1) and without (group 2) AZT treatment over a 6-month period. Whereas MRAMs remained uninfluenced, MRCs showed a clear improvement in the treated group and a decline in the nontreated group, according to the T helper cell counts. MRCs were not only a sensitive test procedure for detecting subclinical lesions in HIV-positive patients, but also a reliable therapy control measurement.

HIV Seropositivity↗
PubMed1991

Anatomical left-right asymmetry of language-related temporal cortex is different in left- and right-handers.

Asymmetry of the planum temporale, a language-related intrasylvian area on the superior temporal gyrus, is the most remarkable anatomical left-right asymmetry of the human brain. The in vivo application of magnetic resonance morphometry in 52 healthy volunteers (26 dextrals and 26 sinistrals) revealed that planum temporale asymmetry is correlated with hand dominance. Left-handers had a significantly lesser degree of leftward planum temporale asymmetry than right-handers. Thus, a structural-functional relation exists in cerebral asymmetry. The correlation is likely to reflect language representation. Because familial sinistrality influenced the anatomical pattern in left-handers and planum temporale asymmetry is already present in the newborn, prenatal factors must play an important role in the development of functional laterality.

Adult↗
PubMed1991

Does tremor pace repetitive voluntary motor behavior in Parkinson's disease?

In patients with Parkinson's disease and in normal subjects, the influence of tremor on repetitive voluntary movement was investigated in the index finger by comparing frequency of isometric force tremor with frequency of voluntary alternating isometric contractions. Tremor frequency, measured over the range from 0 to 70% maximum voluntary force, usually increased with force. The tremor frequency band was lower and more often overlapped with the upper voluntary frequency range in patients than in normal subjects. Normal subjects could accurately produce voluntary contractions at all cue frequencies from 1 to 5 Hz. Patients could produce auditory-paced frequencies of 1 and 2 Hz, but at higher cue frequencies, their voluntary contractions were often faster or slower than the cue. The faster or "hastened" voluntary frequencies were within the tremor frequency band, whereas the slowed voluntary frequencies were below it. Maximal voluntary frequency was often greater than the lowest but always less than the highest tremor frequency. It is concluded that parkinsonian tremor may pace voluntary repetitive movements to go faster than intended with the highest tremor frequency being an upper limit for voluntary frequency. Similar mechanisms may underlie the hastened repetitive vocal responses that were also observed in the parkinsonian patients.

Adult↗
PubMed1991

Reorganisation of descending motor pathways in patients after hemispherectomy and severe hemispheric lesions demonstrated by magnetic brain stimulation.

Numerous clinical studies on patients after hemispherectomy (HS) have provided clear evidence that two distinct groups can be recognized on the basis of the quality of their motor functions after operation. One of these consists of cases where HS was performed after normal brain maturation, the other of patients where the removed hemisphere was damaged early in life. The postoperative motor function has been found to be much better in the latter group. In the present paper it is demonstrated that in contrast to normal subjects ipsilateral compound muscle action potentials (CMAPs) induced by magnetic stimulation of the one intact motor cortex are present in patients after HS. The amplitudes of ipsilateral CMAPs in the muscles roughly correlate with their individual residual motor capacities and show a proximo-distal gradient. In patients with early brain damage prior to HS, CMAPs had short latencies and large amplitudes, whereas in patients with later acquired brain damage prior to HS, CMAPs had long latencies and small amplitudes. It is suggested that reinforcement of the ipsilateral corticospinal pathway may be responsible for residual motor functions in patients with early brain damage, whereas in patients with later acquired brain damage cortico-reticulospinal pathways may play a dominant role in ipsilateral motor control.

Action Potentials↗
PubMed1991

Two cases of cerebral toxoplasmosis in AIDS patients mimicking HIV-related dementia.

Two unusual cases of cerebral toxoplasmosis in AIDS patients are presented. Two homosexual males aged 33 and 52 years in CDC stage IV C1 complained of memory loss during the past 6 months, as well as weight loss and mild fever. They showed severe intellectual deterioration and discrete basal ganglia dysfunction. Motor performance and cognitive function as well as the conventional EEG findings were grossly abnormal. MRI was normal in the younger patient but showed signal-intensive zones in the basal ganglia and cortical atrophy in the older one. CSF and serological antibody tests were normal; immunological function was severely impaired. The patients were diagnosed as late "HIV-related dementia". Both deteriorated rapidly and died within a few weeks. Neuropathological examination revealed histologically severe Toxoplasma gondii encephalitis, involving the basal ganglia in particular. It is concluded that in AIDS patients with a severely impaired immune status cerebral opportunistic infection may present as dementia with mild basal ganglia impairment in the absence of other focal neurological signs or the characteristic radiological findings.

AIDS Dementia Complex↗
PubMed1991

Residual sensorimotor functions in a patient after right-sided hemispherectomy.

Sensorimotor functions were examined in a patient with left-sided infantile hemiparesis who underwent hemispherectomy (HS) on the right side at age 18 for intractable epilepsy. Pathological examination of the removed hemisphere showed a porencephalic cyst of the temporal lobe and of the frontoparietal operculum. On examination, the patient had hemianopia to the left and sensorimotor deficits only of the distal limbs contralateral to the HS. She walked with a barely perceptible limp. Axial and proximal movements were quasi normal, so that the patient could fully elevate both arms, flex and extend the forearm with nearly normal power and execute small, isolated precision movements of the arm around the shoulder joint. This astonishing proximal motor repertoire was mimicked on the somatosensory side where cutaneous sensation and kinesthesia were normal above the elbow and knee and contrasted the pronounced distal sensorimotor dysfunctions. Movement analysis by means of an optoelectronic two-camera position analysis system (Selspot II) showed normal flexion-extension synergies during gait, but abnormal synergic coupling between the shoulder and elbow joint during reaching and prehension. Distal movements were still possible but could only be performed as rigidly coupled movement synergies, such as closing and opening of the fist along with arm adduction/flexion or abduction/extension. She could engage these synergies for grasping and holding large objects. The performance of individual, fractionated finger movements was impossible. Involuntary mirror movements were elicited in both the affected and the normal arm, but with distinctly different phase relationships, indicating that different circuitries contribute to their generation. The case study reveals the existence of a bilaterally organized sensorimotor system that has the potential to provide quasi normal performance of the axial-proximal body parts on both sides. This raises the question why this potential cannot be better used in cases with only partial unilateral brain damage and persistent hemiplegia.

Arachnoid Cysts↗
PubMed1991

Myoclonus and sensorimotor integration in a patient with Ramsay Hunt syndrome.

Clinical and neurophysiologic studies were done on a patient with action myoclonus secondary to Ramsay Hunt syndrome (dyssynergia cerebellaris myoclonica). Myoclonic jerks in the arms were much more common during movements directed to a target than in other movements. They appeared to be triggered primarily by external sensory inputs relevant to the movement rather than by the motor activity itself. Both somatosensory and visual inputs appeared able to trigger the myoclonic jerks. Myoclonic jerks in the deltoid muscle followed finger contact with a target by approximately 100 msec. Electrical stimuli delivered to the fingers during a reaching movement also triggered myoclonic jerks with a similar latency and also evoked giant cortical potentials which preceded the myoclonic jerks in deltoid by 15-20 msec. Our results suggest that during sensory guided movements, sensory inputs relevant to successful completion of the movement may have access to motor systems controlling the muscles involved. In our patient, who likely has lesions involving the cerebellar nuclei and/or cerebellar cortex, these sensory inputs appeared to result in an excessive motor response, possibly through mechanisms involving cerebellar-motor cortex connections.

Adult↗
PubMed1991

Does orthotopic liver transplantation heal Wilson's disease? Clinical follow-up of two liver-transplanted patients.

Two patients with Wilson's disease (WD) underwent orthotopic liver transplantation, one for subacute liver failure and the other for severe oesophageal haemorrhage. After transplantation both patients fully recovered within five months, and copper metabolism returned to normal. Follow-up examinations were continued for 4 and 6 years. Clinical as well as electrophysiological testing in these two patients yielded better results than in most of 12 WD-patients being conventionally treated for a similar period or even longer.

Adult↗