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Multiple Entrapment Neuropathy in the Upper Extremity.

Multiple entrapment neuropathy is compression of more than two nerves in the same extremity. In this case series, 169 patients (208 upper extremities) with this condition were identified, and 124 patients (138 upper extremities) had surgical decompression after an ineffective course of conservative treatment. There were 31 men and 93 women. Average age was 41 years (range 20-87 years). Follow-up averaged 23 months (range 12 to 60 months). Our rating system included patients' self-assessment of overall symptom improvement and return to activity and a physician assessment of strength (grip and pinch) and sensibility (recovery of two-point discrimination). A total of 92 patients (67%) achieved good to excellent results. The clinical features of multiple entrapment neuropathy in our series were presented with a variety of nerve compression syndromes and with a high incidence of regional musculotendinous syndromes. In our surgical treatment, we emphasise simultaneous release of all possible compression sites with a minimally invasive endoscopic approach to achieve better results.

Journal Article↗

Mechanical and thermal hyperalgesia and ectopic neuronal discharge after chronic compression of dorsal root ganglia.

Chronic compression of the dorsal root ganglion (CCD) was produced in adult rats by implanting a stainless steel rod unilaterally into the intervertebral foramen, one rod at L(4) and another at L(5). Two additional groups of rats received either a sham surgery or an acute injury consisting of a transient compression of the ganglion. Withdrawal of the hindpaw was used as evidence of a nocifensive response to mechanical and thermal stimulation of the plantar surface. In addition, extracellular electrophysiological recordings of spontaneous discharges were obtained from dorsal root fibers of formerly compressed ganglia using an in vitro nerve-DRG-dorsal root preparation. The mean threshold force of punctate indentation and the mean threshold temperature of heating required to elicit a 50% incidence of foot withdrawal ipsilateral to the CCD were significantly lower than preoperative values throughout the 35 days of postoperative testing. The number of foot withdrawals ipsilateral to the CCD during a 20-min contact with a temperature-controlled floor was significantly increased over preoperative values throughout postoperative testing when the floor was 4 degrees C (hyperalgesia) and, to a lesser extent, when it was 30 degrees C (spontaneous pain). Stroking the foot with a cotton wisp never elicited a reflex withdrawal before surgery but did so in most rats tested ipsilateral to the CCD during the first 2 postoperative weeks. In contrast, the CCD produced no changes in responses to mechanical or thermal stimuli on the contralateral foot. The sham operation and acute injury produced no change in behavior other than slight, mechanical hyperalgesia for approximately 1 day, ipsilateral to the acute injury. Ectopic spontaneous discharges generated within the chronically compressed ganglion and, occurring in the absence of blood-borne chemicals and without an intact sympathetic nervous system, were recorded from neurons with intact, conducting, myelinated or unmyelinated peripheral nerve fibers. The incidence of spontaneously active myelinated fibers was 8.61% for CCD rats versus 0.96% for previously nonsurgical rats. We hypothesize that a chronic compression of the dorsal root ganglion after certain injuries or diseases of the spine may produce, in neurons with intact axons, abnormal ectopic discharges that originate from the ganglion and potentially contribute to low back pain, sciatica, hyperalgesia, and tactile allodynia.

Animals↗

Neurotrophic factors and diabetic peripheral neuropathy.

Recent evidence from animal models of diabetes and human diabetic subjects suggests that the reduced availability of neurotrophic factors may contribute to the pathogenesis of diabetic peripheral neuropathy (DPN). Of these proteins, nerve growth factor (NGF), brain-derived neurotrophic factor, neurotrophin (NT-3) and NT-4/5 appear to be important for the development and maintenance of peripheral neurons, but others, including insulin-like growth factors (IGFs), may also be involved. Studies with NGF, NT-3, IGF-I and IGF-II both in vitro and in animal models of neuropathies (including DPN) suggest that these factors ameliorate nerve degeneration. Recombinant human NGF is the first neurotrophic factor to enter clinical trials for DPN and is currently being tested in two phase III studies.

Animals↗

Hereditary neuropathy with liability to pressure palsies masquerading as slowly progressive polyneuropathy.

Hereditary neuropathy with liability to pressure palsies (HNLPP) is a peripheral nerve disorder in which recurrent pressure palsies are associated with pathological swelling ('tomacula') of myelinated nerve internodes. We report a patient with a slowly progressive polyneuropathy associated with substantial slowing of conduction velocities initially suggestive of an acquired or hereditary demyelinating polyneuropathy. However, repeat electrodiagnostic studies demonstrated that conduction slowing and partial conduction block were localized primarily to common sites of nerve compression and entrapment. Sural nerve biopsy revealed multiple tomacula consistent with the diagnosis of HNLPP.

Diagnosis, Differential↗

Vestibular nerve compression in eighth-nerve tumors.

The superior vestibular nerve was studied histologically in 25 patients who underwent removal of inferior vestibular nerve schwannoma. In most cases, the nerve fibers were structurally normal but the endoneurial space showed various degrees of capillary stasis and/or extravasation of red blood cells. Increased fibrosis of the endoneurial space was seen in about two-thirds of the cases; it was mild in all except two cases. The endoneurial space appeared edematic in about one-third of the cases. Wallerian degeneration of individual fibers was occasionally observed in most cases and was severe in the two cases with moderate or severe endoneurial fibrosis. In about one-third of the cases there were large numbers of myelinated nerve fibers with thinned myelin sheaths. The observed structural changes are compatible with those seen in human and experimentally induced chronic compressive or entrapment neuropathies. Thus, early symptoms of eighth-nerve tumors might develop due to direct compression of the eighth-nerve trunk within the internal auditory canal.

Cranial Nerve Neoplasms↗

Relationship between retinal nerve fiber layer and visual field sensitivity as measured by optical coherence tomography in chiasmal compression.

PURPOSE: To investigate the spatial relationship between retinal nerve fiber layer (RNFL) thickness measured with optical coherence tomography (OCT) and visual field sensitivity (VFS) measured by standard automated perimetry (SAP) in chiasmal compression. METHODS: Twenty-six patients with chiasmal compression were enrolled. RNFL thickness was measured with the StratusOCT and VFS with SAP (Humphrey Field Analyzer; both from Carl Zeiss Meditec, Dublin, CA). Relationships between RNFL thickness (in clock hours, hemifields, and sectors) and VFS (zones were divided into hemifields, quadrants, and sectors based on a validated visual field map) expressed in a decibel scale and 1/lambert (L) were evaluated by linear and nonlinear regression. Coefficients of determination (R(2)) were calculated by using a multivariate model. RESULTS: Average RNFL thickness correlated strongly with pattern standard deviation (PSD; R = 0.622) and mean deviation (MD; R = 0.413). The four strongest correlations were between the 8 o'clock OCT position (temporal disc), with the temporal hemifield (R = -0.813), the superotemporal quadrant (R = -0.847), the inferotemporal quadrant (R = -0.855), and the field sector representing the papillomacular bundle (R = -0.809). Coefficients of determination improved significantly in all sectors when time since surgery was included in the regression model-most notably, average thickness and 1/L (R(2) = 0.35-0.49), the decibels (R(2) = 0.31-0.47), and the temporal sector (R(2) = 0.44-0.57). CONCLUSIONS: This is the first study to compare the structure-function correlation of RNFL measured by OCT with SAP in patients with chiasmal compression. RNFL is topographically related globally and sectorally to decreased SAP, with the temporal sectors showing the strongest correlations. The correlation between RNFL and VFS strengthens as the time from surgical intervention increases.

Adolescent↗

Effects of facial nerve compression on the stapedial nerve.

A series of experiments on guinea pigs was conducted to determine the prognostic dependability of the stapedial reflex measurement in Bell's palsy. Comparison of the threshold of evoked electromyographic response of the stapedius muscle with that of the orbicularis oris muscle revealed that the stapedial nerve had a lower excitability than did the nerve innervating the orbicularis oris muscle. This lower excitability correlates with the histological finding that the stapedial nerve fibers have a smaller average diameter. The results indicate the resistance of the stapedial nerve to injury of the facial nerve. Functional recovery after cramping of the facial nerve tended to occur later in the stapedial nerve than in the nerve innervating the orbicularis oris muscle. The resistance of the stapedial nerve and the longer period required to recover function in this nerve were factors influencing the prognostic ambiguity of this test.

Animals↗

Systematic review of the diagnosis and management of malignant extradural spinal cord compression: the Cancer Care Ontario Practice Guidelines Initiative's Neuro-Oncology Disease Site Group.

PURPOSE: This systematic review describes the diagnosis and management of adult patients with a suspected or confirmed diagnosis of extradural malignant spinal cord compression (MSCC). METHODS: MEDLINE, CANCERLIT, and the Cochrane Library databases were searched to January 2004 using the following terms: spinal cord compression, nerve compression syndromes, spinal cord neoplasms, clinical trial, meta-analysis, and systematic review. RESULTS: Symptoms for MSCC include sensory changes, autonomic dysfunction, and back pain; however, back pain was not predictive of MSCC. The sensitivity and specificity for magnetic resonance imaging (MRI) range from 0.44 to 0.93 and 0.90 to 0.98, respectively, in the diagnosis of MSCC. The sensitivity and specificity for myelography range from 0.71 to 0.97 and 0.88 to 1.00, respectively. A randomized study detected higher ambulation rates in patients with MSCC who received high-dose dexamethasone before radiotherapy (RT) compared with patients who did not receive corticosteroids before RT (81% v 63% at 3 months, respectively; P = .046). There is no direct evidence that supports or refutes the type of surgery patients should have for the treatment of MSCC, whether surgical salvage should be attempted if patient is progressing on or shortly after RT, and whether patients with spinal instability should be treated with surgery. CONCLUSION: Patients with symptoms of MSCC should be managed to minimize treatment delay. MRI is the preferred imaging technique. Treatment for patients with MSCC should consider pretreatment ambulatory status, comorbidities, technical surgical factors, the presence of bony compression and spinal instability, potential surgical complications, potential RT reactions, and patient preferences.

Adrenal Cortex Hormones↗

Oculomotor nerve repair using interposed nerve graft.

A case of interposed nerve graft repair of an oculomotor nerve damaged during surgery for a laterally growing retrosellar pituitary adenoma is reported. The patient showed partial but functionally useful recovery of nerve function and was able to resume professional work. Only a few reports of end-to-end repair have been published, and they indicate that partial return of nerve function can be expected in such cases.

Adenoma, Chromophobe↗

Experimental chronic entrapment of the sciatic nerve in adult hamsters: an ultrastructural and morphometric study.

Entrapment neuropathy is a group of clinical disorders involving compression of a peripheral nerve and interference with nerve function mostly through traction injury. We have investigated the chronic compression of peripheral nerves as an experimental procedure for detecting changes in ultrastructural nerve morphology. Adult hamsters (Mesocricetus auratus, N = 30) were anesthetized with a 25% pentobarbital solution and received a cuff around the right sciatic nerve. Left sciatic nerves were not operated (control group). Animals survived for varying times (up to 15 weeks), after which they were sacrificed and both sciatic nerves were immediately fixed with a paraformaldehyde solution. Experimental nerves were divided into segments based upon their distance from the site of compression (proximal, entrapment and distal). Semithin and ultrathin sections were obtained and examined by light and electron microscopy. Ultrastructural changes were qualitatively described and data from semithin sections were morphometrically analyzed both in control and in compressed nerves. We observed endoneurial edema along with both perineurial and endoneurial thickening and also the existence of whorled cell-sparse structures (Renaut bodies) in the subperineurial space of compressed sciatic nerves. Morphometric analyses of myelinated axons at the compression sites displayed a remarkable increase in the number of small axons (up to 60%) in comparison with the control axonal number. The distal segment of compressed nerves presented a distinct decrease in axon number (up to 40%) comparatively to the control group. The present experimental model of nerve entrapment in adult hamsters was shown to promote consistent histopathologic alterations analogous to those found in chronic compressive neuropathies.

Animals↗

Prognostic factors for the surgical management of peripheral nerve lesions.

Although the evaluation and treatment of patients with peripheral nerve injuries has evolved and improved over the years, there are still some arguments on the methods and results of surgery. We reviewed retrospectively the clinical, electrophysiological and surgical characteristics of peripheral nerve lesions for 1,636 nerves in 1,565 patients who had been managed in our department in a 10-year period. The most common cause of injuries was gunshot wound in 56.3% of all patients, followed by sharp lacerations (20.6%), fractures (10.6%) and tractions (5.1%). Among 1,636 cases of nerve injuries, the most frequently wounded nerve was median nerve (32.3%), followed by ulnar (24.1%), radial (12.1%), sciatic (10.7%) and peroneal nerves (7.7%), and brachial plexus (7.7%). Simple decompression was the most preferred technique for nerve repair in 27.8%. The electrophysiological improvement was observed in 66.8%, as assessed by electromyography. Clinical improvement was found in 58.4%, as judged by muscle strength grading. If the nerve is compressed or contused, but remains intact, the improvement is satisfactory after surgery. The type of injury, its time of occurrence, initial deficit, and degree of recovery expected are important issues in establishing the treatment plan, which may range from skilled observation to extensive surgical intervention.

Adolescent↗

Nerve lesions associated with limb-lengthening.

BACKGROUND: Nerve injury is one of the most serious complications associated with limb-lengthening. We examined the risk, assessment, and treatment of nerve lesions associated with limb-lengthening. METHODS: We retrospectively studied the records on 814 limb-lengthening procedures. Nerve lesions were defined by clinical signs and symptoms of motor function impairment, sensory alterations, referred pain in the distribution of an affected nerve, and/or positive results of quantitative sensory testing with use of a pressure specified sensory device. RESULTS: Seventy-six (9.3%) of the limbs had a nerve lesion. Eighty-four percent of the nerve lesions occurred during gradual distraction, and 16% occurred immediately following surgery. The pressure specified sensory device showed 100% sensitivity and 86% specificity in the detection of nerve injuries. The patients in whom the lesion was diagnosed with this method, or with this method as well as with nerve conduction studies, had significantly faster recovery than did those diagnosed on the basis of clinical symptoms or nerve conduction studies alone (p = 0.02). Patients undergoing double-level tibial lengthening and those with skeletal dysplasia were at higher risk for nerve lesions (77% and 48%, respectively). Nerve decompression was performed in fifty-three cases (70%). The time between the diagnosis and the surgical decompression was strongly associated with the time to recovery (p = 0.0005). Complete clinical recovery was achieved in seventy-four of the seventy-six cases. CONCLUSIONS: Early detection based on signs and symptoms or testing with a pressure specified sensory device improves the prognosis for nerve injury that occurs during limb-lengthening. Of the methods that we used to identify neurologic compromise, testing with the pressure specified sensory device was the most sensitive. Aggressive early treatment (slowing the rate of lengthening and/or performing decompression) allows continued lengthening without incurring permanent nerve injury. When indicated, decompression of the affected nerve should be performed as soon as possible, thereby improving the chances of and shortening the time to complete recovery.

Bone Lengthening↗

Stimulation of regeneration of the sciatic nerve by experimentally induced inflammation in rats.

The effects of application of a chromic catgut suture (conditioning lesion) placed close to the sciatic or tibial nerves on regeneration of the sciatic nerve after a crush lesion (test lesion), that had been induced after an appropriate conditioning interval (two or four weeks) were assessed. The catgut suture induced an inflammatory reaction around the nerve during the four weeks after application of the catgut suture (conditioning interval) but no signs of degeneration of nerve fibres were seen. There was a significant increase in length of outgrowth of sensory nerve fibres as measured by the pinch reflex test when the test lesion was applied after two and four weeks' exposure to the catgut suture. The rate of regeneration was increased by about 11% when the catgut suture had been applied for four weeks before the test lesion was made. The findings indicate that an inflammatory reaction around a peripheral nerve may act as a conditioning lesion, thereby stimulating regeneration of the nerve.

Animals↗