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PubMed2004

Brainstem auditory evoked potential monitoring during microvascular decompression for hemifacial spasm: intraoperative brainstem auditory evoked potential changes and warning values to prevent hearing loss--prospective study in a consecutive series of 84 patients.

OBJECTIVE: The nerve function of Cranial Nerve VIII is at risk during microvascular decompression for hemifacial spasm. Intraoperative monitoring of brainstem auditory evoked potentials (BAEPs) can be a useful tool to decrease the danger of hearing loss. The aim of this study was 1) to assess the side effects of surgery on hearing and describe the main intraoperative BAEP changes observed in the authors' series, and 2) to define warning values beyond which the probability of hearing impairment rises significantly. These values were calculated by correlating the (possible) postoperative hearing disturbances evaluated in terms of pure tone average with intraoperative BAEP changes (especially delay in Wave V latency). METHODS: This series included 84 consecutive patients affected with hemifacial spasm who underwent microvascular decompression during which BAEPs were monitored. During surgery, Wave I, I to V interpeak interval, latency, and amplitude of Wave V were recorded and measured. Auditory function was studied before and after surgery and expressed as a pure tone average in all patients. Then, correlations were made between hearing impairment after surgery and intraoperative BAEP changes in an attempt to define warning values. RESULTS: Seventy-four patients (88%) had no hearing loss after surgery (Group 1). Eight patients (9.5%) had hearing impairment with a decrease in pure tone average of more than 20 dB (Group 2). Two patients (2.3%) experienced a definitive and complete hearing loss on the side operated on (Group 3). Among intraoperative BAEP changes, latency of Peak V was the most frequently observed and the most significant phenomenon, especially during cerebellar retraction and the decompression step of the microvascular decompression procedure. In the group of patients without hearing loss (Group 1), the mean delay in latency of Peak V was 0.61 millisecond (standard deviation, +/-0.36 ms); in the group with hearing decrease (Group 2), the mean delay was 1.05 milliseconds (standard deviation, +/-0.64 ms); and in the group with deafness (Group 3), Wave V was abolished. CONCLUSION: From a practical standpoint, three warning values, based on delay in latency of Peak V, were established for use during surgery: an initial one at 0.4 millisecond ("watching" signal) at the safety limit; a second one at 0.6 millisecond (risk "warning" signal), which is the mean value corresponding to the group of patients without postoperative hearing loss; and an ultimate one at 1 millisecond ("critical" warning), before irreversibility. These warnings should help the surgeon to avoid or correct maneuvers that are dangerous for hearing function, which is mandatory in functional surgery.

Adult↗
PubMed2004

Functional anatomy of the human cochlear nerve and its role in microvascular decompressions for tinnitus.

OBJECTIVE: The functional anatomy (i.e., tonotopy) of the human cochlear nerve is unknown. A better understanding of the tonotopy of the central nervous system segment of the cochlear nerve and of the pathophysiology of tinnitus might help to ameliorate the disappointing results obtained with microvascular decompressions in patients with tinnitus. METHODS: We assume that vascular compression of the cochlear nerve can induce a frequency-specific form of hearing loss and that when the nerve is successfully decompressed, this hearing loss can recuperate. Thirty-one patients underwent a microvascular decompression of the vestibulocochlear nerve for vertigo or tinnitus. Preoperative audiograms were subtracted from postoperative audiograms, regardless of the surgical result with regard to the tinnitus and vertigo, because the hearing improvement could be the only sign of the vascular compression. The frequency of maximal improvement was then correlated to the site of vascular compression. A tonotopy of the cochlear nerve was thus obtained. RESULTS: A total of 18 correlations can be made between the site of compression and postoperative maximal hearing improvement frequency when 5-dB hearing improvement is used as threshold, 13 when 10-dB improvement is used as threshold. A clear distribution can be seen, with clustering of low frequencies at the posterior and inferior side of the cochlear nerve, close to the brainstem, and close to the root exit zone of the facial nerve. High frequencies are distributed closer to the internal acoustic meatus and more superiorly along the posterior aspect of the cochlear nerve. CONCLUSION: The tonotopic organization of the cisternal segment of the cochlear nerve has an oblique rotatory structure as a result of the rotatory course of the cochlear nerve in the posterior fossa. Knowledge of this tonotopic organization of the auditory nerve in its cisternal course might benefit surgeons who perform microvascular decompression operations for the vestibulocochlear compression syndrome, especially in the treatment of unilateral severe tinnitus.

Adult↗
PubMed2004

Transient magnetic resonance imaging signal alterations in the brainstem after microvascular decompression for trigeminal neuralgia: case report.

OBJECTIVE AND IMPORTANCE: We present a case of transient signal alterations along the brainstem path of the trigeminal nerve after microvascular decompression in a patient with trigeminal neuralgia. Such signal changes have been previously reported to represent infarction, but in our patient, they seemed to represent reactive neural and nuclear changes attributable to operative manipulation. CLINICAL PRESENTATION: A 43-year-old woman presented with gradually increasing, medically refractory recurrent trigeminal neuralgia 16 months after initial successful microvascular decompression for trigeminal neuralgia. Repeat microvascular decompression resulted initially in complete pain relief; however, her pain suddenly returned on the 3rd postoperative day. Magnetic resonance imaging (MRI) of this recurrent pain revealed new signal alterations along the brainstem path of the trigeminal nerve. Other than marked reduction in her trigeminal neuralgia, the patient had no postoperative alterations of trigeminal sensory or motor function. INTERVENTION: The patient's residual postoperative trigeminal neuralgia was successfully treated with carbamazepine. Because of the absence of worrisome signs and symptoms corresponding to the MRI signal alterations, no additional therapy was elected. Follow-up MRI in 1 month revealed near-complete resolution of the postoperative signal alterations along the brainstem path of the trigeminal nerve. CONCLUSION: MRI signal alterations along the brainstem path of the trigeminal nerve after microvascular decompression may be only reactive and do not always represent infarction. Depending on the clinical picture, observation may be all that is necessary in such cases.

Adult↗
PubMed2005

Short-lasting unilateral neuralgiform headache with conjunctival injection and tearing syndrome treated with microvascular decompression of the trigeminal nerve: case report.

OBJECTIVE AND IMPORTANCE: Short-lasting unilateral neuralgiform headache with conjunctival injection and tearing syndrome is a very rare disorder characterized by short-lasting neuralgiform unilateral pain affecting the orbital-periorbital area and associated with autonomic phenomena consisting mainly of conjunctival injection, tearing, and rhinorrhea. Treatment of this condition is difficult; many drugs and surgical procedures have been tried with variable results. In the literature, two cases have been described with short-term response to microvascular decompression of the trigeminal root. We present the case of a patient with short-lasting unilateral neuralgiform headache with conjunctival injection and tearing syndrome who remains asymptomatic 2 years after microvascular decompression. CLINICAL PRESENTATION: A 56-year-old woman was referred to our clinic because she had experienced pain in the distribution of the first left trigeminal branch during the previous 2 years. She experienced paroxysms lasting from a few seconds to 1 to 2 minutes superimposed over a dull sensation of pain involving the same territory. The paroxysms had no refractory period and were triggered by touching the eye or the left side of the face, chewing, yawning, washing her hair, and even by light. Although the paroxysms were triggered by light touch or chewing, she was able to talk or touch herself while having the paroxysm. During pain attacks, she experienced tearing and ipsilateral conjunctival injection, eyelid edema and rhinorrhea, as well as intense photophobia. A magnetic resonance imaging scan revealed a vascular structure distorting and compressing the trigeminal root. INTERVENTION: The patient underwent microvascular decompression of the trigeminal root. At surgery, there was clear compression of the trigeminal root by a superior cerebellar artery loop that was resolved by interposing a Teflon patch. The patient awoke from the operation without pain, and all the accompanying signs and symptoms, such as photophobia, disappeared. The postoperative course was uneventful, and 2 years after treatment, the patient remains asymptomatic. CONCLUSION: Microvascular decompression could be an alternative therapeutic approach to this rare syndrome.

Conjunctival Diseases↗
PubMed2006

Safe intestinal decompression in fresh postoperative gastric bypass.

BACKGROUND: Dilatation of the Roux-limb is sometimes found following Roux-en-Y gastric bypass (RYGBP) procedures. This could be the result of a transient episode due to ileus, or a partial or complete obstruction. The risk of this complication is an increase in intraluminal pressure with the potential for leak. Blind insertion of a nasogastric tube for decompression could be risky due to possible perforation at the stapled or sutured edges. METHODS AND RESULTS: The diagnosis was made with routine extended upper gastrointestinal x-rays 24 hours after surgery. To determine the relationship of the intestinal dilatation, increase in intraluminal pressures and leaks, measurements were taken in porcine models duplicating a RYGBP. Pressures obtained at the anastomoses were higher than pressures in the jejunum between the anastomoses, and related directly to the production of leaks. Elevations of intraluminal intestinal pressures have also been observed in patients who required decompression. The angles of a freshly constructed pouch and the recent stapled or sutured edges may be easily perforated with a nasogastric tube, especially a hard one. We use a soft flexible tube. An angled-end 0.035" wire is introduced into the intestines with fluoroscopic assistance. The tube tip is perforated with a needle, and through this opening, the wire is passed into the tube. The tube is then fed over the wire for safe decompression. CONCLUSION: Decreasing the intestinal pressure by safe decompression may avoid one of the causes of leaks.

Decompression, Surgical↗
PubMed2005

Decompressive craniectomy with clot evacuation in large hemispheric hypertensive intracerebral hemorrhage.

INTRODUCTION: Decompressive hemicraniectomy in large hemispheric infarctions has been reported to lower mortality and improve the unfavorable outcomes. Hematoma volume is a powerful predictor of 30-day mortality in patients with intracerebral hemorrhage (ICH). Hematoma volume adds to intracranial volume and may lead to life-threatening elevation of intracranial pressure. METHODS: Records of 12 consecutive patients with hypertensive ICH treated with decompressive hemicraniectomy were reviewed. The data collected included Glasgow Coma Scale (GCS) score at admission and before surgery, ICH volume, ICH score, and a clinical grading scale for ICH that accurately risk-stratifies patients regarding 30-day mortality. Outcome was assessed as immediate mortality and modified Rankin Score (mRS) at the last follow-up. RESULTS: Of the 12 patients with decompressive hemicraniectomy, 11 (92%) survived to discharge; of those 11, 6 (54.5%) had good functional outcome, defined as a mRS of 0 to 3 (mean follow-up: 17.13 months; range: 2-39 months). The mean age was 49.8 years (range: 19-76 years). Three of the 7 patients with pupillary abnormalities made a good recovery; of the 11 patients with intraventricular extensions (IVEs), 7 made a good recovery. The clinical finding (which was present in all 3 patients with mRS equal to 5 and which was not present in patients with mRS less than 5) was abnormal occulocephalic reflex. Of the 10 patients with an ICH score of 3, 9 (90%) survived to discharge, 4 (44%) had good functional outcome (mRS: 1-3). Hematoma volume was 60 cm3 or greater in eight patients, four (50%) of whom had good functional outcome (mRS: 0-3). CONCLUSION: Decompressive hemicraniectomy with hematoma evacuation is life-saving and improves unfavorable outcomes in a select group of young patients with large right hemispherical ICH.

Adult↗
PubMed1998

Survival analysis of hips treated with core decompression or vascularized fibular grafting because of avascular necrosis.

Avascular necrosis of the femoral head is a multifaceted process that leads to articular incongruity and subsequent osteoarthrosis of the joint. Clinicians concur that primary treatment should focus on preservation of the natural surface of the joint; however, there has not been a consensus on how best to accomplish this. While a number of therapeutic interventions have been reported, the efficacy has varied markedly and there have been few statistical comparisons. The purpose of the current study was to use statistical analysis to compare the results of two widely used procedures, vascularized fibular grafting (614 hips; 480 patients) and core decompression (ninety-eight hips; seventy-two patients), for the treatment of avascular necrosis. The patients were stratified according to age and the stage of disease, and a survival analysis was performed with total hip arthroplasty as the end point for failure. None of the eleven hips that had Ficat stage-I disease needed a total joint replacement after being treated with either regimen. Analysis of the hips that had stage-II disease revealed rates of survival, at fifty months, of 65 per cent (twenty-eight of forty-three hips) after core decompression and 89 per cent (ninety-nine of 111 hips) after vascularized fibular grafting. For the hips that had Ficat stage-III disease, the rates of survival at fifty months were 21 per cent (ten of forty-seven hips) after core decompression and 81 per cent (405 of 500 hips) after vascularized fibular grafting. Among the hips that had Ficat stage-II or III disease, the rate of eventual total joint arthroplasty after vascularized fibular grafting was significantly lower than that after core decompression (p < 0.0001). The results indicate that the increased morbidity associated with vascularized fibular grafting is justified by the associated delay in or prevention of articular collapse in hips that have stage-II or III disease.

Adult↗
PubMed1999

Survivorship analysis of hips treated with core decompression for nontraumatic osteonecrosis of the femoral head.

We reviewed the long-term results of core decompression for the treatment of nontraumatic osteonecrosis of the femoral head, performed in thirty-four patients (fifty-four hips) between January 1, 1981, and June 30, 1995. Twenty patients (59 percent) had bilateral involvement. The mean age of the patients at the time of presentation was thirty-eight years (range, twenty-two to eighty-three years). The presumed risk factors were use of corticosteroids (thirty-seven hips), excessive intake of alcohol (eight hips), and use of adrenocorticotropic hormone for the treatment of multiple sclerosis (two hips); the remaining seven hips had idiopathic osteonecrosis. According to a modification of the classification system of Ficat and Arlet in combination with the system of Steinberg et al., thirteen hips were stage I (normal radiographs) preoperatively; seven, stage IIA sclerotic; sixteen, stage IIA cystic or sclerocystic; ten, stage IIB (transitional stage, with a crescent sign); and eight, stage III (collapse). The mean duration of follow-up after the core decompression was 120 months (range, twenty-four to 196 months). The result was considered successful if the patient was asymptomatic, with no progression of the disease, and unsuccessful if there was radiographic failure (progression to stage III [collapse]) or clinical failure (the need for a subsequent operation), or both. The Kaplan-Meier product-limit method was used to estimate clinical and radiographic survival. Overall, twenty-six hips (48 percent) had a satisfactory clinical result and twenty (37 percent) survived according to radiographic criteria. Radiographic or clinical failure, or both, were seen in four of the thirteen stage-I hips, none of the seven stage-IIA sclerotic hips, thirteen of the sixteen stage-IIA cystic or sclerocystic hips, nine of the ten stage-IIB hips, and all eight stage-III hips. On the basis of the Cox proportional-hazards regression model, significant predictors of overall failure included an advanced preoperative radiographic stage (p < 0.0001), a shorter duration of symptoms (p < 0.05), and use of corticosteroids (p < 0.05). No association was found between age, gender, excessive intake of alcohol, or renal transplantation and the overall outcome. Two patients (two hips; 4 percent) had a postoperative complication. One patient had a fracture of the femoral neck, and the other had a hematoma. Our findings suggest that core decompression is a safe and effective procedure for the treatment of stage-I or stage-IIA sclerotic disease. These data also demonstrate the importance of differentiating between stage-IIA sclerotic disease and stage-IIA cystic or sclerocystic disease. We believe that core decompression has a limited role in the operative management of patients who have evidence of cystic changes in the femoral head on plain radiographs.

Adult↗
PubMed2001

Arthroscopic resection of the distal aspect of the clavicle with concomitant subacromial decompression.

BACKGROUND: Arthroscopic subacromial decompression and arthroscopic resection of the acromioclavicular joint as separate procedures have been well documented. However, there is little information on the success rate of resection with concomitant decompression. In this study, we retrospectively evaluated the results of a consecutive group of patients who underwent arthroscopic resection of the acromioclavicular joint with concomitant subacromial decompression. METHODS: We evaluated the surgical results in thirty-one consecutive patients (thirty-two shoulders) with acromioclavicular pathology with concomitant subacromial impingement. The mean age of the patients at the time of surgery was thirty-six years (range, eighteen to sixty-seven years). Twenty-five patients, including four professional athletes, were actively involved in sports activities. The mean duration of follow-up was four years and ten months (range, three to eight years). The follow-up examination included clinical evaluation, chart review, radiographic analysis, and isokinetic testing of both upper extremities. RESULTS: Of the twenty-five patients who participated in sports, twenty-two (including the four professional athletes) returned to their previous level of sports activity. Twenty-six patients had no pain, three reported mild pain on strenuous repetitive overhead activity, two (both weight-lifters) had occasional pain in the acromioclavicular joint and the lateral aspect of the shoulder with bench-pressing, and two (both baseball players) had mild pain in the posterior aspect of the shoulder with throwing. All of the patients were satisfied with the results. In the absence of a complete rotator cuff tear, isokinetic strength-testing of both upper extremities failed to demonstrate any weakness of the involved shoulder. The mean functional score for individual activities was 2.7 points (range, 2.1 to 3.0 points) preoperatively and 3.9 points (range, 3.6 to 4.0 points) postoperatively (p = 0.0001). No patient had superior migration of the clavicle. The amount of distal clavicular resection averaged 9 mm (range, 7 to 15 mm). One patient had heterotopic ossification at the resection site, with mild pain on direct palpation of the acromioclavicular joint and on strenuous overhead activity. Five patients had calcification at the anterior deltoid insertion into the acromion that was asymptomatic, with no impingement on overhead activity and no pain on direct palpation. CONCLUSIONS: We found excellent results with arthroscopic resection of the acromioclavicular joint and concomitant subacromial decompression. When this procedure is performed on properly selected patients, the results are similar to those of an open approach.

Acromioclavicular Joint↗
PubMed1989

Decompression sickness and arterial gas embolism in sports scuba divers.

Diving underwater with breathing apparatus is an increasingly popular sport. Consequently, the number of diving-related accidents, including both decompression sickness and arterial gas embolism, have increased. Though both involve bubbles, decompression sickness is a disease which involves gas bubbles forming in tissues and venous blood, while arterial gas embolism results from the introduction of gas bubbles directly into the arterial circulation. Although the pathologies and natural histories of decompression sickness and arterial gas embolism are different, the treatment of these conditions is essentially the same. Compression in a recompression chamber is the definitive treatment of both decompression sickness and arterial gas embolism, and any delay before treatment must be minimised if a good outcome is desired.

Arteries↗
PubMed1999

Neurovascular decompression for trigeminal neuralgia in elderly patients.

The operative findings and outcomes of neurovascular decompression for trigeminal neuralgia were compared between patients aged 75 years and older (elderly group, 17 patients) and patients aged under 75 years (nonelderly group, 115 patients). There were no statistically significant differences in the operative findings or outcomes between the two groups, except in the percentage of patients who had been treated with carbamazepine. Neurovascular decompression for trigeminal neuralgia can be performed in elderly patients with the same operative results as in nonelderly patients. If other treatments (especially carbamazepine treatment) prove ineffective, neurovascular decompression should be considered in elderly patients before they become too old to undergo surgery. However, neurovascular decompression in elderly patients requires great care, as the venous system, including the superior petrosal vein, should be preserved and retraction of the cerebellum should be avoided whenever possible to maintain correct blood circulation in the cerebellum and brainstem.

Aged↗
PubMed2003

Expanded polytetrafluoroethylene membrane for prevention of adhesions in patients undergoing external decompression and subsequent cranioplasty.

Cranioplasty performed after external decompression for brain swelling may be difficult because of the development of adhesions between the temporal muscle and the dura. Membranes composed of expanded polytetrafluoroethylene (ePTFE) were inserted at external decompression to prevent such adhesions. The ePTFE membranes were placed suturelessly between the temporal muscle and the dura, covering the proximal portion of the temporal muscle at the sphenoidal ridge and the dural suture line. In addition, part of the membrane was placed directly below the skin incision to allow easy visualization at subsequent cranioplasty in 10 patients. Cranioplasty was performed 38 to 126 days (mean 63.9 days) after external decompression. No adhesions were observed, either between the ePTFE membranes and the dura, or between the membranes and the temporal muscle. No temporal muscle and dural injuries occurred during cranioplasty, and no patient showed signs of infection. Mean operating time was 71.0 minutes and mean blood loss was 75.2 ml. Sutureless insertion of ePTFE membranes at external decompression increases the ease and safety of subsequent cranioplasty, decreases operating time and blood loss, and avoids injury to the temporal muscle and dura.

Adult↗
PubMed2001

Microsurgical decompression without laminectomy in lumbar spinal stenosis.

Our objectives were to study a/ the clinical results of microsurgical decompression without laminectomy compared to those reported from standard decompression laminectomy in patients with central lumbar spinal stenosis, and b/ if the microsurgical technique could prevent post-operative instability and concomitant symptoms. Twenty-one patients were treated, 11 men and 10 women, aged 47-81 years. Fourteen patients had "pure" stenosis whereas 7 had additional diseases that compounded the symptoms of stenosis. Independent examiners saw the patients pre-operatively and a mean of 27 months post-operatively. Plain X-ray films were taken of 14 patients a mean of 5 years post-operatively to study possible slippage. Among the 14 patients with "pure" stenosis the results were excellent in 13 and fair in 1. Among the 7 with additional diseases the outcome was excellent in 1, fair in 1, unchanged in 3 and worse in 2. The technique did not prevent post-operative slippage, which occurred in 3 of 14 patients. However, the clinical outcome was not related to slippage. We found the microsurgical technique safe and gentle with excellent possibilities for decompression of the complete spinal canal without laminectomy. The results following this procedure were well comparable to or even better than those reported following standard decompression laminectomy.

Aged↗
PubMed2003

Revision surgery for Chiari malformation decompression.

Chiari malformations comprise four different hindbrain anomalies originally described by Hans Chiari, a professor of pathology at the German University in Prague. There are four basic Chiari malformations. The reasons for revision of Chiari malformation decompression may be for conservative or inadequate initial decompression or the development of postoperative complications. Another reason involves cases of both hindbrain herniation and syringomyelia in patients who have undergone adequate posterior fossa decompression without resolution of symptoms, signs, or radiological appearance of their syrinx cavity. Additionally, symptom recurrence has been reported in association with various types of dural grafts. Reoperation or revision surgery for patients with Chiari malformations is common and may not be due to technical error or inadequate decompression. The types of revision surgeries, their indications, and initial presentations will be reviewed.

Adolescent↗
PubMed2000

Microvascular decompression for cochlear symptoms.

OBJECT: The object of this study was to evaluate the efficacy of a new neurovascular decompression technique in relieving symptoms of cochlear nerve dysfunction. METHODS: Nineteen patients with slowly progressive hearing loss, low-frequency fluctuating hearing loss, and high-pitched tinnitus due to neurovascular compression (NVC) of the eighth cranial nerve in a triangular space between the seventh and eighth cranial nerves (the VII-VIII triangle) of the cerebellopontine angle (CPA) were treated using a new technique for microvascular decompression that was developed by anatomical study in 24 cadaver specimens of the CPA. In 12 of 19 patients the anterior inferior cerebellar artery (AICA) was observed to cause compression in the VII-VIII triangle and this vessel was easily mobilized medially for placement of a silicone sponge or Teflon cushion between the compressing artery and nerve. Postoperatively, hearing loss of 20 dB or more that was present in 11 of the 19 patients with NVC improved by more than 5 dB in seven (64%), including the patient with the most severe hearing loss. Of 18 patients presenting with tinnitus preoperatively, eight (44%) had no tinnitus and an additional nine (for a total of 94%) had good improvement in tinnitus after surgery and at long-term follow up. CONCLUSIONS: The microvascular decompression technique described is highly successful in treating symptoms due to direct or indirect compression of the cochlear nerve, with minimal risk of complications. Recordings of auditory brainstem responses confirmed the clinical diagnosis of NVC of the eighth cranial nerve and correlated with clinical results after microvascular decompression of the cochlear nerve.

Adult↗
PubMed2002

Magnetic resonance neurography studies of the median nerve before and after carpal tunnel decompression.

OBJECT: Recently developed novel MR protocols called MR neurography, which feature conspicuity for nerve, have been shown to demonstrate signal change and altered median nerve configuration in patients with median nerve compression. The postoperative course following median nerve decompression can be problematic, with persistent symptoms and abnormal results on electrophysiological studies for some months, despite successful surgical decompression. The authors undertook a prospective study in patients with carpal tunnel syndrome, correlating the clinical, electrophysiological, and MR neurography findings before and 3 months after surgery. METHODS: Thirty patients and eight control volunteers were recruited to the study. The MR neurography consisted of axial and sagittal images (TR = 2000 msec, TE = 60 msec) obtained using a temporomandibular surface coil, fat saturation, and flow suppression. Maximum intensity projection images were used to follow the median nerve through the carpal tunnel in the sagittal plane. Magnetic resonance neurography in patients with carpal tunnel syndrome demonstrated proximal swelling (p < 0.001) and high signal change in the nerve, together with increased flattening ratios (p < 0.001) and loss of nerve signal in the distal carpal tunnel (p < 0.05). Sagittal images were very effective in precisely demonstrating the site and severity of nerve compression. After surgery, division of the flexor retinaculum could be demonstrated in all cases. Changes in nerve configuration, including increased cross-sectional area, and reduced flattening ratios (p < 0.001) were seen in all patients. In many cases restoration of the T. signal intensity toward that of controls was seen in the median nerve in the distal carpal tunnel. Sagittal images were excellent in demonstrating expansion of the nerve at the site of surgical decompression. CONCLUSIONS: In this study the authors suggest that MR neurography is an effective means of both confirming compression of the median nerve and its successful surgical decompression in patients with carpal tunnel syndrome. This modality may prove useful in the assessment of unconfirmed or complex cases of carpal tunnel syndrome both before and after surgery.

Carpal Tunnel Syndrome↗
PubMed2004

Persistent syringomyelia following pediatric Chiari I decompression: radiological and surgical findings.

OBJECT: The incidence of syringomyelia in patients with Chiari I malformation is reported to be between 20 and 75%. In the series reported herein 10.6% of patients with both clinical entities have continued to have a significant syrinx following their first decompressive procedure. All but one patient had resolution of their syrinx after a second posterior fossa operation. The authors have analyzed this smaller group of patients to look for possible radiological or surgical findings that may aid in predicting which patients are less likely to respond to the initial first decompressive procedure. METHODS: The authors retrospectively reviewed radiological and operative data in eight patients who continued to have syringomyelia following a decompressive procedure. Seven (88%) of these patients had complete resolution of their syrinx following a second operation. At repeated operation, obstruction at the foramen of Magendie was seen in six patients. In one patient in whom the dura was not opened during first operation, the second operation revealed an arachnoid veil that occluded the foramen of Magendie. CONCLUSIONS: No single radiological measurement was found to aid in the prediction of which patients would not respond to the first decompressive procedure. Furthermore, no operative finding was extraordinarily unique to any single patient. All but one patient in whom confirmation of a patent foramen of Magendie was made at repeated operation-that is, lysing of arachnoid veils, stent placement, unilateral tonsillar coagulation-had resolution of their syringomyelia. Surgical reexploration should be considered in cases of persistent syringomyelia.

Adolescent↗
PubMed2004

Foramen magnum cerebrospinal fluid flow characteristics in children with Chiari I malformation before and after craniocervical decompression.

OBJECT: The Chiari I malformation presents significant challenges to clinicians because its pathophysiology is not well understood. In conducting cerebrospinal fluid (CSF) flow studies, investigators have attempted to correlate the clinical severity of these lesions with general flow velocity or bulk flow at the foramen magnum; however, these techniques have not allowed consistent prediction of symptomatology, explanation of the presence of syringomyelia, or the assessment of the hydrodynamic characteristics of the decompression. The authors used temporally and spatially resolved flow analyses to assess the characteristics of CSF flow in children with Chiari I malformation and the changes in these flow characteristics that occur after suboccipital decompression. METHODS: The authors studied eight children with symptomatic Chiari I malformation with or without syringomyelia and two children without Chiari I malformation. All patients underwent phase-contrast magnetic resonance imaging before and after posterior fossa decompression. Velocity plots were displayed for each voxel. Several indices of CSF flow were developed to characterize the flow patterns associated with Chiari I malformation. In children with symptomatic Chiari I malformation, even though bulk flow or velocity is often normal, there was marked heterogeneity of flow at the foramen magnum. This was evident for several reasons: 1) an increase in cephalad and caudad peak velocities; 2) spatial inhomogeneity in velocities; 3) simultaneous bidirectional flow; and 4) substantial net craniad or caudad flows within particular voxels and subregions during the cardiac cycle. After posterior fossa decompression, the severity of these flow abnormalities decreased. CONCLUSIONS: Foramen magnum CSF flow in children with symptomatic Chiari I malformations is spatially and temporally heterogeneous, and this heterogeneity improves postoperatively. The authors propose that relying on mean flow parameters in patients with Chiari I malformation is no longer sufficient; instead, more elaborate techniques to analyze foramen magnum CSF flow have become necessary.

Adolescent↗