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Biomedical subjects

C Krarup

Publications and source records attributed to C Krarup.

At least 55 records · Page 3Linked to original sources
PubMed1990

The carpal tunnel syndrome: diagnostic utility of the history and physical examination findings.

STUDY OBJECTIVE: To assess the value of a history and physical examination findings in diagnosing the carpal tunnel syndrome, and to determine whether constellations of clinical findings identify patients at high or low risk for the carpal tunnel syndrome. DESIGN: Comparison of diagnostic tests with neurophysiologic testing. SETTING: Patients with upper extremity complaints of diverse causes referred to a neurophysiology laboratory for diagnostic studies. METHODS: Before nerve conduction testing, a history, demographic and physical examination data, and a hand pain diagram were obtained from each patient. Diagrams were categorized as indicating the classic carpal tunnel syndrome, or as probable, possible, or unlikely to indicate the carpal tunnel syndrome. Associations between clinical data and nerve conduction results were examined in univariate and multivariate analyses. RESULTS: Of 110 patients in the study, 44 (40%) had the carpal tunnel syndrome. Individually, the best predictors were hand pain diagram rating (positive predictive value, 0.59; 95% CI, 0.48 to 0.68) and Tinel sign (positive predictive value, 0.55, CI, 0.45 to 0.65). The combination of a positive Tinel sign and a probable or classic diagram rating had a positive predictive value of 0.71; CI, 0.53 to 0.85. Other findings from physical examination and the history were less useful. Just 9% of patients under 40 years of age with possible or unlikely diagram ratings had the carpal tunnel syndrome. CONCLUSIONS: With the exceptions of age, Tinel sign, and hand pain diagram rating, findings from the physical examination and the history had limited diagnostic utility. Patients under 40 years of age with possible or unlikely diagram ratings were at low risk for the carpal tunnel syndrome. This finding, which should be confirmed in an independent population, suggests that subsets of patients may be managed without nerve conduction studies.

Adult↗
PubMed1990

Nerve regeneration and reinnervation after limb amputation and replantation: clinical and physiological findings.

A 22-year-old male was studied 3 1/2-4 1/2 years after a traumatic section-avulsion amputation of the left upper extremity at the level of the distal humerus. The arm was reattached after a cold ischemia time of 4-5 hours and good vascularization was obtained. The ulnar nerve was repaired early with an end-to-end juncture while the median and radial nerves were repaired after seven months delay using a combination of vascularized radial nerve and nonvascularized sural nerve grafts. Some intrinsic hand muscle function had recovered. Pin-prick and touch sensation was present in all digits, although localization of touch stimulation was poor. Evoked motor responses had recovered by 25-50% of control amplitude in ulnar-innervated and by 10-25% in median-innervated muscles. Amplitudes of sensory responses from digit V had recovered by 25% and from digits I and III by 1-5%. Fast-adapting touch receptors had become reinnervated. There was electrophysiological evidence of aberrant sensory regeneration and of abnormal connections between sensory and motor fibers. Digital blood flow measurements suggested the presence of vascular obstruction in vessels of the replanted upper extremity. However, the digital vasoconstriction during cold exposure indicated regeneration of sympathetic nerve fibers.

Adult↗
PubMed1990

A syndrome of asymmetric limb weakness with motor conduction block.

We describe 3 patients with asymmetric limb weakness, fasciculations (2 patients), relatively preserved reflexes, normal cranial nerves, and few or no sensory abnormalities. The symptoms had been progressive over 1 to 15 years. Detailed motor nerve conduction studies showed conduction block and slowing localized to sharply circumscribed areas 30 to 100 mm long in several nerves in each patient. By contrast, the sensory conduction studies over the same nerve segments were normal, indicating very selective involvement of motor fibers. Sural nerve biopsies showed minor changes that varied among the patients. One patient had high levels of anti-GM1 antibodies, 1 had mildly elevated levels, and 1 had high levels of only asialo-GM1 antibodies. Treatment with immune suppressive therapy has produced minimal improvement in 1 patient.

Electrophysiology↗
PubMed1989

Perioperative nerve lesions.

The scenario is all too familiar. A patient has a surgical procedure. Anesthesia is uneventful and the procedure goes well. Nothing untoward is observed in the recovery room. Later that evening the patient complains of numbness, weakness, or pain, and a neurological deficit is found. A neurologist is called, examines the patient, and it is concluded that a nerve lesion has occurred, because of stretch, ischemia, compression, or laceration. A subsequent electromyogram and nerve conduction study confirm the clinical impression, but offer little in the way of explanation. Over the subsequent months, the patient makes a slow recovery but there has been a prolonged period of pain and disability. Liability issues loom. This scenario could reflect a number of different nerve lesions. This review illustrates the different modes of pathogenesis that may occur and the variable nature of the neurological deficits. We grouped these lesions according to the clinical setting in which they occur.

Brachial Plexus↗
PubMed1989

Modulation of the bulbocavernosus reflex during voiding: loss of inhibition in upper motor neuron lesions.

The bulbocavernosus reflex (BCR) is a sacral segmental reflex which is suppressed throughout most of micturition. The BCR was evaluated by recording the associated EMG activity using a concentric needle electrode placed in the external urethral sphincter. The influence of the central nervous system (CNS) on the BCR was studied in 29 neurologically normal individuals and in 33 patients with upper motor neuron (UMN) lesions and voiding dysfunction. Ninety percent (26/29) of the neurologically normal patients did not have a BCR during most of micturition. By comparison, all the patients with an UMN lesion had a positive BCR beginning early during voiding. The finding of suprasegmental modulation of the BCR during voiding demonstrated by external urethral sphincter EMG was a more sensitive although slightly less specific sign of UMN bladder dysfunction than detrusor sphincter dyssynergia; uninhibited bladder contractions were neither sensitive nor specific for UMN lesions.

Adolescent↗
PubMed1989

Conduction studies in peripheral cat nerve using implanted electrodes: III. The effects of prolonged constriction on the distal nerve segment.

Electrophysiological properties were monitored in detail in chronically constricted peripheral nerves by implanted, multicontact nerve cuff electrodes and correlated with morphometric histology in selected cases. The physiological and histological responses in nerve to a range of constricting cuffs of standard sizes were readily graded. The initial response to any significant constriction was a transient, focal conduction slowing or block at the constriction, followed by more protracted distal effects; the latter ranged from loss of excitability consistent with "dying-back" degeneration to reductions in conduction velocity consistent with histologically observed atrophy. Smaller myelinated fibers tended to have similar but less pronounced changes than larger diameter fibers. Recordings from ventral and dorsal roots showed that distal degeneration was more pronounced in motor than in sensory fibers of similar caliber. Electronmicroscopical measurements showed that basal laminas were relatively preserved around even the most atrophic and demyelinated axons. Perimeter measurements of the basal lamina could be used to estimate the diameter of the original nerve fiber.

Animals↗
PubMed1989

Idiopathic brachial plexus lesion with conduction block of the ulnar nerve.

A 24-year-old male with idiopathic acute aching of the right wrist, weakness of ulnar innervated muscles of the forearm and hand, and numbness of the ulnar two digits, was examined electrophysiologically. Conduction studies showed almost complete conduction block of motor fibers of the ulnar nerve distally in the brachial plexus. Sensory fibers were less affected. The symptoms and pathophysiological findings improved over a period of 1-2 months and were normal at the final study performed 7 months after presentation. There was mild evidence of chronic partial denervation of the abductor digiti V and the flexor digitorum profundus of the two ulnar digits. There were additional mild EMG changes of the abductor pollicis muscle indicating minor involvement of the median nerve. There was no traumatic or other obvious cause for these findings. It is suggested that the patient had a mild and abortive form of brachial plexus neuropathy presenting as a demyelinating lesion rather than the more typical wallerian degeneration seen in most established cases.

Action Potentials↗
PubMed1989

The unrecognized neuropathic bladder of infancy.

Four infants presented with hydroureteronephrosis and incomplete emptying of the bladder secondary to detrusor-sphincter dyssynergia. None of the patients had other signs suggestive of neurological dysfunction. It is presumed but not proved that these infants manifested a urodynamic reaction in response to a perinatal insult involving the brainstem area. Long-term followup has demonstrated a persistent but nonprogressive neurourological disturbance.

Electromyography↗
PubMed1988

Conduction studies in peripheral cat nerve using implanted electrodes: I. Methods and findings in controls.

Silicone rubber cuff and patch electrodes with multiple contacts were implanted along the sciatic-tibial-plantar nerves in cat for repeated studies of conduction properties of normal peripheral nerve over periods of time. The contacts were used in various combinations for precise localization of changes in conduction velocities and excitability along the extent of normal nerves. In this paper the particular characteristics and limitations associated with cuff-electrode recordings of neural activity are discussed. The nerve action potential was recorded using a tripolar configuration with a central lead flanked by two shunted leads at symmetrical distances. This configuration records the spatial derivative of the action potential and rejects potentials from sources outside the cuff. The voltage changes are restricted by the silicone cuff, and the dynamic range is therefore very high, allowing detection from single myelinated fibers to whole nerve responses. The electrodes are well suited for following the development of regeneration and degeneration following experimental lesions.

Action Potentials↗
PubMed1988

Conduction studies in peripheral cat nerve using implanted electrodes: II. The effects of prolonged constriction on regeneration of crushed nerve fibers.

Arrays of chronically implanted electrodes were used to examine the time course of elongation and maturation of peripheral nerve fibers in the cat after crush of the tibial nerve in the proximal calf. Regeneration after crush alone was compared with crush 5 mm proximal to a tight constriction of the nerve. Regeneration was monitored by the progression of excitability along the electrode arrays on the tibial and plantar nerves. The sensitivity was sufficient to record the averaged activity in single nerve fibers allowing detection of the earliest regeneration. The diameters of the fastest regenerating fibers were estimated from the conduction velocity proximal to the site of crush. Both after crush alone, and after crush constriction, small myelinated fibers regenerated in front of large fibers. The rate of elongation after crush alone was 3.2 mm/day, whereas it was slower (P less than 0.02) distal to crush + constriction (2.2 mm/day). In both lesions, the extrapolated delay to onset of regeneration was 8 days. In observations up to 300 days after crush, maturation was delayed or impaired by the constriction, and the compound nerve action potential had a smaller amplitude and a dispersed shape. Transverse sections of nerves after crush + constriction showed a diminished number of large and an increased number of small fibers compared with crush alone, possibly due to persistent branching of regenerated fibers. After both crush alone and crush + constriction, regenerated fibers had similar g ratios, suggesting that myelination developed fully in fibers of diminished diameters.

Action Potentials↗
PubMed1988

Cold-induced peripheral nerve damage: involvement of touch receptors of the foot.

A 31-year-old male developed paresthesia and numbness of mainly the right foot following exposure to nonfreezing temperatures under moist conditions over a period of 1 week. The symptoms gradually improved over several months. When seen for electrophysiological studies 6 months after the injury, there was no sensory loss on clinical examination, although he continued to complain of distal numbness of the right foot. The right extensor digitorum brevis muscle was atrophic, and the distal motor latency in the peroneal nerve was prolonged. Conduction studies of the right sural nerve showed a predominantly distal diminution of the SAP evoked by electrical stimulation at the dorsum pedis. Action potentials evoked by tactile stimulation of Pacinian corpuscles showed a prolonged latency on the symptomatic side, suggesting that the most pronounced pathological changes in immersion injury may be localized to the very distal portion of the nerve at the nerve fiber-receptor junction.

Action Potentials↗
PubMed1988

Neurourological implications of the changing approach in management of occult spinal lesions.

Occult lesions of the spine in children are a rare but recognizable cause of neurogenic dysfunction involving the lower extremities, and lower urinary and gastrointestinal tracts. We report the preoperative and postoperative urodynamic findings in 40 children with varying spinal abnormalities. Of these patients 28 were neonates or infants (average age 8.7 months) and 12 were older children (average age 11.7 years). Preoperative urodynamic testing revealed normal function in 18 of 28 children (64 per cent) in the younger age group in contrast to 1 of 12 (8 per cent) in the older age group. Of the 10 infants with abnormal studies postoperative urodynamic findings returned to normal in 6, while 2 others remained abnormal but were improved. In contrast, of 11 older children with abnormal preoperative evaluations 3 (27 per cent) reverted to normal postoperatively. The neurourological changes seen in these occult lesions are variable, may occur at any age, are progressive and are potentially reversible by surgical correction but this reversibility diminishes with age.

Adolescent↗
PubMed1987

The changing neurourologic lesion in myelodysplasia.

Seventy-nine newborns with myelodysplasia were followed up for 1 1/2 to six years with serial roentgenographic, neurologic, and urodynamic evaluations. Twenty-nine infants (37%) demonstrated changes in external urethral sphincter innervation during the first three years of life. Of the group who changed, 896% (25/29 infants) did so in the first year, 10% (3/29 infants) in the second year, and 4% (1/29 infants) in the third. The risk factor for change was 32%, 6%, and 2%, respectively, during each of these three years. Fifteen infants (19% of the total) experienced neurourologic deterioration while 14 infants (18%) improved. Seven newborns underwent a second neurosurgical procedure resulting in improvement in four, stabilization in two, and further deterioration in one. These findings underline the importance of early and continued neurologic and urologic surveillance in children with myelodysplasia because it is a dynamic disease process.

Electromyography↗
PubMed1987

Peripheral neuropathy in mitochondrial disease.

Clinical, electrophysiological, histological and biochemical studies of two patients with mitochondrial disease revealed a moderately advanced axonal neuropathy with mitochondrial paracrystalline inclusions in Schwann cells, fibroblasts and muscle fibers. In addition there was a myopathy, and the activity of muscle cytochrome c oxidase was diminished by more than 50%. There were electrophysiological signs of myopathy, neuropathy and failure of excitation-contraction coupling in both patients. The partial enzyme deficiency raises some questions as to its pathogenetic role in these neuromyopathies.

Adult↗
PubMed1987

Urodynamic assessment of children with cerebral palsy.

More than a third of the children with cerebral palsy present with dysfunctional voiding symptoms. Clinical evaluation and urodynamic study of cerebral palsy patients were performed to characterize the symptoms, to define the type of neurological deficit and to document its effect on voiding dynamics. We evaluated flow rate, and cystometrographic and external sphincter electromyographic findings in 57 children with cerebral palsy. Upper and lower motor neuron lesions were defined by standard criteria. Of the children 86 per cent had evidence of a pure upper motor neuron injury and 11 per cent manifested electromyographic findings suggestive of incomplete lower motor neuron sphincteric injury. The latter deficit could not be predicted on the basis of clinical neurological findings but it was suggested by a history of neonatal cyanosis. Treatment protocols achieved continence in more than 75 per cent of the children. The voiding dynamics in children with cerebral palsy have not been assessed previously. We have defined the lower urinary tract dysfunction in these patients, and provide a rational and effective plan of management.

Adolescent↗
PubMed1985

Some effects of prolonged constriction on nerve regeneration in the rabbit.

Serial nerve conduction studies have been used to study the time-course of regeneration after tibial nerve crush in the rabbit, and the effect on this of a constricting ligature 5 mm distal to the site of crush. Transverse sections from the region of the ligature showed that when constriction was severe, the regenerating fibers had difficulty in penetrating the constricted region, and that some took an aberrant course in superficial connective tissue outside the ligature. In 2 out of 6 animals no fibres succeeded in passing through the centre of ligature, but aberrant fibres were able to re-enter distal fascicles and to reinnervate distal muscles. When compared with findings after crush alone, the time taken to reinnervate distal muscles was increased by a ligature, and distal fibre diameter and motor conduction velocity remained low. Low voltage, long-duration, polyphasic muscle action potentials were evoked by distal nerve stimulation, and axon reflexes suggested excessive axon branching within nerve trunks. Since these changes were seen in the distal parts of both constricted and aberrant fibres, they cannot be attributed to constriction alone. Similar changes might be expected in other peripheral nerve lesions in which loss of fascicular continuity and neuroma formation occur.

Animals↗
PubMed1983

Evoked responses in normal and diseased muscle with particular reference to twitch potentiation.

The compound muscle action potential and isometric twitch tension evoked by single and repetitive electrical stimuli are indicators of the number of motor units activated and of the contractile properties of the muscle. The action potentials and mechanical responses were recorded in proximal and distal muscles in patients with myasthenia gravis and myopathy and compared with findings in normal subjects. In normal muscle, at low rates of stimulation (2-3 s-1) the decrement was at most 5% in the action potential and 15-24% in the twitch tension. Tetanic stimuli (50 s-1) were unsuitable for diagnostic purposes because of movement artefact. In patients with myasthenia gravis, the incidence and size of the decrement of evoked responses were greater in the platysma than in the elbow flexors and the adductor pollicis (ADP) muscles. The 2-3 times greater post-tetanic facilitation (PTF) of the action potential in the platysma than in extremity muscles also indicates a more severe functional block in facial muscle. The PTF is an indicator of recruitment of blocked fibres. The maximal decrement was grossly related to the titre of antibodies against the acetylcholine receptor. To reveal failure of neuromuscular transmission in patients with myasthenia gravis without a decrement, a small dose of d-tubocurarine (0.2 mg in 30 ml of saline) was injected i.v. in the upper arm in a regional curare test. The sensitivity was greater in patients with myasthenia gravis than in controls and in patients with myopathy. Potentiation of twitch tension reflects contractile properties. In normal muscle twitch potentiation in the staircase (1-3 s-1, 100 s in duration) and after tetanus (50 s-1, 1.5 s in duration) was 2-3 times greater in the platysma than in the elbow flexors and ADP, presumably related to the greater proportion of fast-twitch fibers in facial muscle. The amplitude of the action potential and the twitch tension varied proportionally with the number of fibers activated and the difference in the decrements of the action potential and the twitch during the staircase in some patients with myasthenia gravis showed that the staircase phenomenon was diminished suggesting abnormalities in the excitation-contraction coupling. The diminution of the staircase and post-tetanic potentiation (PTP) in myopathy also indicates impairment of the excitation-contraction coupling. In rats with severe chronic myasthenia gravis, the staircase and PTP were decreased even when the failing neuromuscular transmission was circumvented by applying direct stimuli to the extensor digitorum longus muscle (EDL).

Action Potentials↗