Christian Krarup

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.

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.

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.

Electrophysiological Study of Recovery of Peripheral Nerves Regenerated by a Collagen-Glycosaminoglycan Copolymer Matrix

We have studied the effects of variations in the structure of a collagen-glycosaminoglycan (CG) copolymer matrix on the regeneration of transected rat sciatic nerves. Silicone tubes ensheathing 10-mm lengths of CG copolymer were grafted between the transected sciatic nerve stumps. Empty and saline-filled silicone tubes, as well as autografts, were studied as controls. The mean pore diameter and the degradation rate of the copolymer in collagenase were independently varied to investigate how each affects regeneration. Electrophysiological properties of the regenerating motor nerve fibers innervating the plantar flexor muscles, were serially monitored over about 40 weeks following surgery. Rapidly degrading CG copolymers with pore channels oriented predominantly along the axes of the tubes induced regeneration with a success rate of 100% (n = 35). Although CG copolymers with axially-oriented pore channels that degraded slowly had a success rate as high as 96% (n = 23), the long-term electrophysiological results were markedly inferior to those obtained with the rapidly degrading grafts. In another study of axially-oriented pore structures, the level of recovery of long-term electrophysiological results was observed to increase monotonously as preliminary results showed that CG copolymers with pore channels predominantly oriented along the radial direction of the tubes had a success rate of only 50% (n = 6). Control groups of empty and saline-filled tubes had an aggregated success rate of 29% (n = 21). The ongoing study has shown that systematic physiochemical manipulation of simple chemical analogs of the extracellular matrix can be used to define substrate features which encourage regeneration.

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.

The Development of Collagen Nerve Conduits that Promote Peripheral Nerve Regeneration

We have investigated the repair of peripheral nerves in animal models using tubular guiding conduits. The materials used to fabricate the nerve conduits and their physicochemical and mechanical characteristics can influence the extent, rate and morphology of regeneration. Permeability of the conduit membranes is one parameter which seems to play an important role in nerve regeneration. In the present study, two types of nerve conduits were developed from bovine tendon collagen with distinctly different permeabilities. The permeability of the conduit membranes was determined by diffusion of various sized molecules across these membranes. One type of conduit had pores which only allowed small molecules such as glucose to pass (small pore collagen conduits). The other type had pores which were readily permeable to macromolecules such as bovine serum albumin (large pore collagen conduits). The large pore collagen conduits supported nerve regeneration to a greater degree than the small pore collagen conduits when tested in mice to bridge 4 mm gaps of the sciatic nerve. Studies in rats and primates suggested that large pore collagen conduits worked as effectively as nerve autografts in terms of physiological recovery of motor and sensory responses. The results of in vitro and in vivo studies of these conduits represent a significant step towards our specific aim of developing suitable off-the-shelf prostheses for clinical repair of damaged peripheral nerves.

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.

Conduction Properties in Peripheral Nerve Fibers Regenerated by Biodegradable Polymer Matrix

The rat sciatic nerve was transected mid-thigh and grafted with a silicone tube, the central 10 mm of which was filled with a collagen-glycosaminoglycan (CG) matrix. The rats were grafted contralaterally with empty silicone tubes as controls. The earliest compound muscle action potentials (CMAPs) at the plantar muscles were recorded around 11 weeks. After 30 weeks, the distal motor latencies recovered to about 50% higher than normal, the conduction velocity to about 50% normal, and the amplitudes of the CMAPs to about 50% normal. Of 7 rats in this study, all 7 nerves grafted with the CG matrix exhibited recovery, while only 1 grafted with the empty tube exhibited recovery. The CG matrix therefore appears to promote functional nerve regeneration across extended distances.

Requirement for A 1-µm Pore Channel Opening During Perifheral Nerve Regeneration through a Biodegradable Chemical Analog of ECM

A continuing study of preferences of elongating axons and Schwann cells for specific matrix features has revealed an apparently critical structural requirement. Well-defined, chemical analogs of ECM based on a collagen-glycosaminoglycan (CG) copolymer were used to bridge a 10-mm gap between cut ends of the rat sciatic nerve. The nerve stumps and the CG matrix bridging them were ensheathed in a silicone tube. Electrophysiological properties of regenerating motor nerve fibers innervating the plantar flexor muscles were serially monitored over 40 weeks following surgery. The results suggest that functional recovery of motor function requires the presence of an average pore diameter of order 1 µm. These results pose novel questions about the nature of cell-matrix interactions during nerve regeneration.