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Effects of increased systemic blood pressure on the tissue fluid pressure threshold of peripheral nerve.

This study was designed to evaluate the functional response of the median nerve at the wrist to various degrees of acute, local compression in hypertensive patients. After measuring resting tissue fluid pressure in the carpal tunnel of the nondominant hand of nine subjects (diastolic pressures of 90 mm Hg or greater), localized pressures of 50, 60, or 70 mm Hg were applied to the palmar aspect of the wrist. Motor and sensory latencies and amplitudes of the median nerve were evaluated before compression, during 30-240 min of compression, and during the postcompression recovery phase. Sensory responses were completely blocked at a threshold tissue fluid pressure of 60-70 mm Hg, measured by the wick catheter technique. This pressure threshold was greater than the 40-50 mm Hg previously found in normotensive subjects. The tissue pressure threshold of normotensive and hypertensive subjects was consistently 30 mm Hg below diastolic blood pressure (approximately 45 mm Hg below mean arterial blood pressure). These results support the concept that ischemia is the prime mechanism of conduction block in low pressure, nerve-compression syndromes.

Action Potentials↗

Anterior subfascial transposition of the ulnar nerve.

After anterior subfascial transposition, the ulnar nerve lies superficial to the flexor-pronator muscle group but deep to its fascia. Eight patients with cubital tunnel syndrome were treated with this method and reviewed retrospectively. The average age at the time of operation was 52 years. All patients had severe cubital tunnel syndrome based on Dellon's classification. The average follow-up period was 2 years and 9 months. Post-operative outcome assessment was based on the modified Bishop rating system. Six patients had excellent and two had good outcomes. All were back at work by the 5th post-operative week. There were no complications or recurrence of symptoms. Anterior subfascial transposition of the ulnar nerve is an effective method of surgical treatment for patients with severe cubital tunnel syndrome.

Adult↗

[Anterior interosseous nerve syndrome].

Two cases of Kiloh-Nevin syndrome are reported and the operative possibilities discussed. The difficulties in predicting nerve regeneration complicate the choice of treatment.

Adult↗

Electrodiagnostic testing in hand surgery.

General techniques of electrodiagnostic examination, how such examination can predict the pathophysiology of nerve injury, and specific techniques and findings of the major entrapments such as carpal tunnel syndrome and ulnar nerve neuropathy are described in detail. Additional disease states that relate to hand surgery, such as anterior interosseous syndrome, brachial plexopathy, radiculopathy, polyneuropathy, and the nebulous entity of thoracic outlet syndrome are discussed.

Brachial Plexus↗

Intradural-extramedullary cavernous hemangioma of the left motor root C7--case report and update of the literature.

OBJECTIVE: Intradural-extramedullary cavernomas of the spine are rare lesions with only 21 published cases to date. Due to their rareness and special characteristics diagnosis often is difficult. We report on an additional case of an intradural-extramedullary cavernoma of the spine. PATIENT: A 56-year-old male presented with left shoulder pain and acute onset of pain affecting the whole spinal column two weeks prior to admission. There were no motor deficits, but a hypesthesia corresponding to the right distal C8-dermatome. MRI revealed an intradural-extramedullary, expansive lesion at the level of C6 with a hyperintense appearance in both T (1)- and T (2)-weighted images. Neither a hemosiderin rim nor contrast enhancement was visible. RESULTS: During surgery a hematoma and a reddish, berry-like tumor adherent to the left motor root C7 were removed. There were no new neurological deficits, and shoulder and back pain resolved within a few weeks after surgery. Histopathologically a cavernous hemangioma was diagnosed. CONCLUSIONS: The patient's symptoms were caused both by direct nerve compression and by spinal hemorrhage, most likely spinal SAH. As there was no characteristic hemosiderin rim and due to the hyperintense appearance in T (1)- and T (2)-weighted MR scans, a radiological diagnosis of hemorrhage and classification of the lesion was difficult. Despite their rareness, in patients with signs of spontaneous, spinal SAH and/or nerve compression syndromes cavernous hemangiomas have to be considered as a potential cause.

Hemangioma, Cavernous, Central Nervous System↗

Management of work-related upper-extremity nerve entrapments.

Peripheral nerve symptoms are common in the worker. Great care must be given to obtain an accurate diagnosis. Diagnostic labels should not be used unless one is sure of the diagnosis. A detailed evaluation of the worker, job, and medical and psychosocial conditions must be performed. Nonoperative treatment is primary. Understanding at-risk patients and managing them carefully can decrease disability and improve results following treatment. The results from surgery are less successful in work-related disorders and disability is often prolonged. Surgery should only be performed for clear diagnoses and clear indications after adequate nonoperative treatment, with careful consideration of the job to which the worker will return.

Carpal Tunnel Syndrome↗

Sub-clinical entrapment neuropathy in man.

Twelve median and 12 ulnar nerves were obtained at routine autopsies from patients without known disease of the peripheral nervous system. Enlargement of cross-sectional area due to an increase in connective tissue elements was commonly present in the ulnar nerve at the elbow and in the median nerve under the flexor retinaculum. Renaut bodies were also prominent at these two sites. The connective tissue changes did not appear to be related to the presence or absence of nerve fibre damage. When nerve fibres were teased apart and examined individually, localised changes were found at the elbow in 5 ulnar nerves and under the flexor retinaculum in 5 median nerves. The changes were mild and transverse sections at the same levels showed few abnormalities. However, the changes were similar in character to those described previously in experimental animals with entrapment syndromes. They are therefore considered to be valid evidence of sub-clinical entrapment in apparently unaffected human subjects.

Acute Disease↗

AAEM case report #1: ulnar neuropathy at the elbow.

A patient with bilateral cubital syndrome complicated by anomalous innervation is presented. The electrodiagnostic approach to patients with this neuropathy is reviewed emphasizing new developments. The interpretation of the findings in this patient centers around issues of pathophysiology and methodology.

Axons↗

Double gluteus maximus muscle with associated variations in the gluteal region.

We report bilateral muscular and neurovascular anomalies of the gluteal region in a cadaver. On the right side, the gluteus maximus muscle had two parts, one of which was fibrous and the other muscular. In addition, there were duplicated piriformis muscles and high division of the sciatic nerve. The common peroneal nerve passed between the two parts of the piriformis muscle, and the tibial nerve emerged from under the lower piriformis muscle (infrapiriform foramen). At the same time the internal pudendal vessels and pudendal nerve passed over the sacrotuberous ligament on the left side. The double piriformis muscles and high division of the nerve are known as an anomaly which is believed to cause a nerve compression syndrome called the syndrome of the piriformis muscle. To the best of our knowledge anomalies of the gluteus maximus muscle and pudendal structures have not yet been reported. This complex anomaly should be kept in mind in connection with intramuscular injections of the gluteal region, the piriformis syndrome, and the surgery of this region.

Adult↗

Stress testing in nerve compression.

Peripheral nerve compression syndromes most often produce neuropathic changes that are recordable by conventional electrophysiologic testing techniques. Occasionally, a patient exhibits all the appropriate clinical signs, symptoms, and history of a compartment syndrome, such as a carpal tunnel syndrome, but electrophysiologic testing procedures will be normal, thus seeming to identify no neuropathic component to the syndrome. Researchers have reasonably concluded that wrist position or hand activity can have an adverse affect on intracompartmental carpal pressures, with resultant ischemic changes in epineural blood supply and subsequent compromise in nerve conduction parameters during and for a short time after the ischemic event. The stress testing protocol presented here identifies such changes, which would otherwise go undetected or undocumented and which may lead to unsuccessful clinical decisions regarding management. Sample tracings of actual cases are presented to demonstrate actual changes produced by the use of the protocol. This test protocol is used only when conventional testing is normal in the presence of appropriate clinical symptomatology.

Carpal Tunnel Syndrome↗

Incipient cauda equina syndrome as a model of somatovisceral pain in dogs: spinal cord structures involved as revealed by the expression of c-fos and NADPH diaphorase activity.

Segmental and laminar distribution of Fos-like immunoreactive, reduced nicotinamide adenine dinucleotide phosphate diaphorase (NADPHd)-exhibiting and double-labeled (Fos-like immunoreactive and NADPHd-exhibiting) neurons was examined in lower lumbar and sacral segments of the dog spinal cord using the model of multiple cauda equina constrictions. NADPHd histochemistry was used as marker of nitric oxide synthase-containing neurons. The appearance and the time-course of Fos-like immunoreactive, NADPHd and double-labeled neurons was studied at 2 h and 8 h postconstriction characterized as the incipient phase of cauda equina syndrome. The occurrence of Fos-like immunoreactive and NADPHd-exhibiting neurons in fully developed cauda equina syndrome was studied at five days postconstriction. An increase in Fos-like immunoreactivity in superficial laminae (I-II) and an enhanced NADPHd staining of lamina VIII neurons were found. A statistically significant increase in Fos-like immunoreactive neurons was found in laminae I-II and VIII-X 8 h postconstriction, and in contrast, a prominent decrease in Fos-like immunoreactive neurons was found in laminae I-II, accompanied by a statistically significant increase in Fos-like immunoreactive neurons in more ventrally located laminae VII-X at five days postconstriction. Quantitative analysis of laminar distribution of constriction-induced NADPHd-exhibiting neurons revealed a considerable increase in these neurons in laminae VIII-IX 8 h postconstriction and a statistically highly significant increase in NADPHd-exhibiting neurons in laminae VII-X five days postconstriction. Concurrently, the number of NADPHd-exhibiting neurons in laminae I-II was greatly reduced. While a low number of double-labeled neurons was found throughout the gray matter of lower lumbar and sacral segments at 2 h postconstriction, a statistically significant number of double-labeled neurons was found in lamina X 8 h and in laminae VII-X five days postconstriction. The course and distribution of anterograde degeneration resulting five days after multiple cauda equina constrictions are compared with segmental and laminar distribution of Fos-like immunoreactive and NADPHd-exhibiting neurons. Prominent involvement of the spinal cord neurons appearing in the lumbosacral segments at the early beginning and in fully developed cauda equina syndrome results in a Fos-like immunoreactivity and strongly enhanced NADPHd staining of some neuronal pools. Under such circumstances, an early cauda equina decompression surgery is advisable aimed at decreasing or preventing the derangement of the neural circuits in the lumbosacral segments.

Animals↗

Reoperation in high ulnar neuropathy.

Twenty-two reoperations were done on 16 arms in 14 patients who had previously been unsuccessfully treated by neurolysis for cubital tunnel syndrome. For the first reoperation subcutaneous transposition was chosen for 10 arms, and submuscular transposition for six. The symptoms were cured or improved in seven arms, eight were unchanged and one was made worse. In six arms in which first neurolysis and then subcutaneous transposition had been unsuccessful, submuscular transposition was carried out. Five patients were improved or cured, and the symptoms were unchanged in one. Reoperation after ulnar neurolysis therefore gave satisfactory results in about half the cases. Submuscular transposition carried out as a second reoperation may be useful in cases in which subcutaneous transposition had not been successful.

Adolescent↗

[Infarction of the spinal cord in the posterior spinal arterial supply area as a result of intervertebral disc embolism (author's transl)].

A female patient aged 49 developed an acute transverse lesion of the spinal cord from D11 downwards. Autopsy revealed spinal cord infarcts mainly in the dorsal parts corresponding to the posterior spinal arterial supply area, caused by multiple arterial and venous fibrocartilaginous emboli. This particular cause of spinal vascular syndrome has been reported previously only in 11 patients, all outside Austria. This case report serves to stress the poor clinical delineation of a distinct "posterior spinal syndrome". The source of the emboli is the intervertebral disc, mainly the nucleus pulposus. The spinal cord vessels are probably entered by the following route: extrusion of disc material into the venous bone marrow sinus (probably favoured by trauma or endocrine factors) yield basivertebral veins yield internal vertebral venous plexus; the spread is supported by blood stream changes caused by increased intraabdominal/intrathoracic pressure; there is also the possibility of direct penetration of disc material into the internal vertebral plexus, as demonstrated in dogs yield radicular veins yield meningeal and cord veins; sometimes entry occurs through arteriovenous shunts into cord arteries. The true incidence of this condition is unknown since cases are likely to be overlooked in the absence of extensive histopathological investigation.

Accidents, Home↗

Median nerve mononeuropathy in spondylotic cervical myelopathy: double crush syndrome?

We studied the association between spondylotic cervical myelopathy (SCM) and median nerve mononeuropathy (MNM) and examined the validity of the double-crush hypothesis. Sixty consecutive patients with clinically overt spondylotic cervical myelopathy were examined by means of nerve conduction studies, electromyography, and median nerve somatosensory evoked potentials; the frequency of the electrophysiological signs of focal MNM at the wrist was compared with that of a control group comprising 100 sex- and age-matched patients. Electrophysiological signs of MNM were found in 20 myelopathic patients (33%) in comparison with an 11% prevalence in the control group (P<0.05). The signs of motor anterior horn cell lesion at the C8-Th1 level and concomitant motor axonal MNM ipsilaterally were found in three hands, while the signs of sensory axonal loss at C6-7 segments due to ganglionic or postganglionic sensory lesion outside the wrist and concomitant sensory axonal MNM were present in one hand. While demonstrating a statistically significant association between SCM and MNM, we found no evidence of an etiological relationship between these two conditions. Electrophysiological signs of MNM fail anatomical (segmental level and side) and pathophysiological (axonal type of lesion) requirements of the double-crush hypothesis in most of patients with concomitant SCM and MNM.

Adult↗

An experimental animal model of spinal root compression syndrome: an analysis of morphological changes of myelinated axons during compression radiculopathy and after decompression.

The treatment of radicular pain is mainly empirical because there are only few experimental studies dealing with morphological changes during compression radiculopathy. The goal of the study was to investigate changes in the morphology of myelinated axons during spinal root compression and the influence of decompression in a new rat model. The number of myelinated axons and their diameter were measured at 1, 2, 5, and 8 weeks during compression of the dorsal spinal root. The same approach was applied for 1-week compression followed by decompression for 1 or 2 weeks and compression for 5 weeks followed by 3-week decompression. A decrease in the number of myelinated axons (particularly those of large diameters) occurred after compression for 1 week. Continued compression for up to 8 weeks resulted in centripetal increase in the number of myelinated axons and the persistence of a small fraction of large myelinated axons at the site of compression. After that time, a decreased number of axons and a reduced fraction of large myelinated axons occurred again. Decompression after 1-week compression caused a rapid increase in the number of both small and large myelinated axons within the spinal root including the site of compression. A small fraction of regenerated axons was found after 5-week compression followed by 3-week decompression. Finally, we investigated the time course of the temporary increase in the number of regenerated myelinated axons during dorsal root compression for up to 8 weeks. The efficacy of decompression was superior when applied one week after compression or after regress of the acute phase of aseptic inflammation associated with fragility of spinal root. The results of the study verify the need for early surgical decompression to prevent irreversible damage of the spinal roots.

Animals↗

[Hypothesis concerning the anatomical basis of cauda equina syndrome and transient nerve root irritation after spinal anesthesia].

OBJECTIVE: Cauda equine syndrome is a rare neurological complication associated with subarachnoid anesthesia, and particularly with the use of 5% hyperbaric lidocaine and small gauge catheters. Our aim was to study a possible anatomical factor that might impede adequate dilution of local anesthetic and explain the development of cauda equine syndrome and transitory radicular irritation. MATERIAL AND METHOD: The spinal dura matters and their contents from two male human cadavers were examined after organs had been extracted for transplantation. Both men had recently died at ages 56 and 65 years of age. Samples were fixed in a glutaraldehyde phosphate buffer and dehydrated in acetone, which was then removed by critical point elimination. The samples were then metallized with gold and observed under a scanning electron microscope. RESULTS: We found that one portion of the arachnoids was more compact and another was lax. The compact portion had a laminar structure formed by the fusion of fibers and cell components lining the inner surface of the dural mater. The lax portion was comprised of a weblike network of filaments and few cells bodies. This portion extended from the compact inner arachnoid lamina to the cell plane of the pia mater, where it dispersed, sending out compact arachnoid projections that wrapped around structures in the subarachnoid space. We termed these wrappings "arachnoid sheaths".

Aged↗