Iatrogenic peripheral nerve damage and its forensic evaluation

Iatrogenic peripheral nervous lesions represent a regrettable complication of medical therapy. Legal regulations of the GDR make it possible for the practicing physician to remain an advocate of the patient's interests. The results of an analysis of 11 years of activities in the Magdeburg County Commission of Medical Experts are presented.     

Concentrating cerebrospinal fluid cells with the sedimentation chamber--comparative methodologic studies

The loss of cerebrospinal fluid cells is considerable when the sedimentation chamber was used. Methodical variations resulted in an increasing cell count on the slide. The absolute number of lymphocytes increased more than that of monocytes. Caused by the higher cell count, especially lymphocytes, the relative values in cell differentiation between lymphocytes and monocytes are changed. For differential counting of lymphocytes, monocytes and other cerebrospinal fluid cell types the elevated cell count is an important factor. Differentiation between subpopulations of lymphocytes by means of this procedure however is problematically because the loss of lymphocytes can be of a selective nature.     

Recent advances in electron-beam-induced damage models in yttria fully stabilized zirconia single crystals

Dislocation loop formation in yttria fully stabilized zirconia single crystals observed in a transmission electron microscope has been reported in the literature. To account for the loop formation, two different explanations have been proposed. Here we present original experiments focusing on a comparison of the two models. We conclude that the origin of the loops is precipitation of a second phase, enhanced by heating in the electron beam.     

Surgery of therapy-resistant pain due to peripheral nerve injury]

1. The forms of peripherally triggered or localized pains are differentiated: Local pain of a neuromatous character, propagated pain, sympathalgia, phantom pain, causalgia, and combined forms. 2. Surgical operations are performed locally, to the spinal cord, brain, and sympathicus, as well as by neurostimulation on all levels. 3. The areas of indication differ according to the localization of pain and its probable cause. 4. Serving the prevention of pain after peripheral nerve injuries are the particular topical treatment of a fresh injury, psychic guidance, specific aftercare and physiotherapy, elimination of pension payment problems, and optimum reintegration into normal working life]     

Intelligence, reaction times, and peripheral nerve conduction velocity

Two studies (with sample sizes of 85 and 88) are reported that investigated relationships among measures of intelligence, speed of information processing, and peripheral nerve conduction velocity (NCV). In both studies, NCV was significantly correlated with IQ scores (rs = .42 and .48) and with reaction times (RTs; rs = −.28 and −.18): Thus, faster NCV was associated with higher IQ scores and faster speed of processing. In both studies, NCV and RTs contributed significantly, in combination, to the prediction of fullscale IQ (shrunken multiple Rs = .53 and .57), but the expected pattern of causal relationships between the variables was not borne out. The results are interpreted in terms of a “neural efficiency” model of intelligence, which has recieved support from other studies of physiological correlates of human intelligence.     

Acute and chronic peripheral nerve stimulation: Surgical preparation and electrode design

An electrode for peripheral nerve stimulation and surgical procedures for implantation are described. Results indicating its effectiveness are provided with discussion of durability and applicability.     

Influence of temperature on the bioelectric conductivity of peripheral motor nerve]

14 persons were examined electro-neurographically before and after cooling with an ice bag. The following results were found. A slight decrease of the motor conductivity is verified. This decrease in function is shown most markedly in the slowly-conducting motor neurons. At the cooling borderlines reactions with increased function are discernible. For the clarification of the relevance of changes of the nerve conductivity, further investigations with methodic variants are necessary.     

Changes in stereotyped central motor patterns controlling vocalization are induced by peripheral nerve injury.

Adult male zebra finches (Taeniopygia guttata), as closed-ended learners, normally crystallize their songs at 90 days of age, and the song remains fixed throughout life (Price, 1979). We show that injuring the tracheosyringeal nerve(s) (each of which innervates the ipsilateral half of the syrinx, the avian vocal organ) results in a short-term deficit in the syllables forming adult male song; this deficit disappears after ts nerve regeneration. However, when adult males were followed for a period of several weeks after unilateral tracheosyringeal nerve injury, long-term changes occurred in the temporal patterning of song. Syllables were deleted, remaining portions of the song were linked, and new syllables were added. Syllables with call-like morphology were less likely to be deleted from and more likely to be added to the song. Deletions were most often contiguous chunks of syllables. Changes in the temporal patterning of song occurred during specific periods following nerve injury, were completed within 100 days after nerve transection, and were not dependent upon regeneration of the ts nerve. The resulting newly formed song patterns were stable, remaining unchanged up to 1 year later. The ability of adult male zebra finches to make specific types of changes to crystallized song indicates that some form of vocal plasticity remains even after song learning is completed, though this plasticity may be restricted to a subset of song characteristics. The limitations on the types of changes that are possible may reflect how song is centrally organized.     

Deficits of anticipatory grip force control after damage to peripheral and central sensorimotor systems

Healthy subjects adjust their grip force economically to the weight of a hand-held object. In addition, inertial loads, which arise from arm movements with the grasped object, are anticipated by parallel grip force modulations. Internal forward models have been proposed to predict the consequences of voluntary movements. Anesthesia of the fingers impairs grip force economy but the feedforward character of the grip force/load coupling is preserved. To further analyze the role of sensory input for internal forward models and to characterize the consequences of central nervous system damage for anticipatory grip force control, we measured grip force behavior in neurological patients. We tested a group of stroke patients with varying degrees of impaired fine motor control and sensory loss, a single patient with complete and permanent differentation from all tactile and proprioceptive input, and a group of patients with amyotrophic lateral sclerosis (ALS) that exclusively impairs the motor system without affecting sensory modalities. Increased grip forces were a common finding in all patients. Sensory deficits were a strong but not the only predictor of impaired grip force economy. The feedforward mode of grip force control was typically preserved in the stroke patients despite their central sensory deficits, but was severely disturbed in the patient with peripheral sensory deafferentation and in a minority of stroke patients. Moderate deficits of feedforward control were also obvious in ALS patients. Thus, the function of the internal forward model and the precision of grip force production may depend on a complex anatomical and functional network of sensory and motor structures and their interaction in time and space.     

Further studies on the psychophysics of irregular nerve action potential patterns

In this paper we consider two problems concerning human psychophysical discriminability of variable interval nerve action potential patterns. The first question asks which of two possible alternatives-additional sample size or elongation of duration-is responsible for the improvement in performance as the number of pulses in a stimulus train increases. Our data strongly indicated that the answer to this question is increased sample size. The second question concerns what effect, if any, parallel rather than serial presentation of the two alternatives in a forced choice psychophysical test will have on the function relating interpulse interval and discriminability. The answer to this question appears to be that other than a slight elevation of the absolute levels no changes in the general form of the response is produced.     

Linguistic abilities in patients with prefrontal damage

The language abilities of 21 patients with prefrontal lesions (11 right and 10 left) and 15 matched normal subjects were analyzed, using a linguistic ability test designed to evaluate performance in six areas: automatic language, language production, verbal memory, syntax, derivative words, and comprehension of logical grammatical structures. Significant differences in the obtained scores of all groups were found. In spite of formal conservation of language in patients with frontal damage, their complex and conceptual verbal abilities were severely compromised.     

Memory strategies with brain damage

The ability of anterograde amnesics with and without a history of alcoholism and patients with frontal lobe damage to think about memory, memorizing, and remembering was assessed. Alcoholic Korsakoffs' and frontal lobe patients' knowledge and use of memory strategies was deficient when compared with controls whereas nonalcoholic amnesics' was not. The use of the categorization mnemonic was assessed in a verbal learning experiment. Frontal lobe patients failed to spontaneously categorize a categorizable word list when trying to memorize it. Nevertheless, when forced to categorize the list, they benefited from the imposed structure. Nonalcoholic amnesics spontaneously categorized the list and benefited from the resulting organization.     

Superior fluid intelligence in children with Asperger's disorder

Asperger's disorder is one of autistic spectrum disorders; sharing clinical features with autism, but without developmental delay in language acquisition. There have been some studies of intellectual functioning in autism so far, but very few in Asperger's disorder. In the present study, we investigated abstract reasoning ability, whose form of intelligence has been labeled fluid intelligence in the theory of Cattell [Cattell, R. B. (1963). Theory of fluid and crystallized intelligence: A critical experiment. Journal of Educational Psychology, 54, 1-22.], in children with Asperger's disorder. A test of fluid intelligence, the Raven's Standard Progressive Matrices Test, was administered to 17 children with Asperger's disorder and 17 age-, gender-, and FIQ-matched normal children. The results showed that children with Asperger's disorder outperformed on the test of fluid reasoning than typically developing children. We suggest that individuals with Asperger's disorder have higher fluid reasoning ability than normal individuals, highlighting superior fluid intelligence.     

The effect of ischemia on the peripheral nerve action potential in man and its relation to somatosensory magnitude coding

The amplitude and latency fluctuations of the compound action potential of the ulnar nerve were recorded percutaneously as a function of the length of time the arm was kept ischemic by means of an inflated sphygmomanometer cuff. Changes in latency and the amplitude action potential were measured for cuff positions above and below the recording electrode. The amplitude fluctuations were shown to be related to corresponding changes in the sensory threshold which has been determined in an earlier study. By manipulating the position of the cuff it was possible to determine that the amplitude fluctuations were caused by a reduced number of nerve action potentials rather than a change in the individual atonal action potential amplitude.     

Disfluent speech associated with brain damage

The frequency and type of disfluencies in the spontaneous speech of 15 people with Broca's aphasia and right hemiplegia was studied. Two aged-matched control groups (15 nonaphasic stroke patients with left hemiplegia and 15 normals) were also studied. The frequency of disfluencies in the speech of aphasics was three times greater than that in the speech of either control group. However, most of the disfluencies uttered by aphasics were of the types commonly found in speech of normals.