Biomedical subjects

M Samii

Publications and source records attributed to M Samii.

At least 145 records · Page 8Linked to original sources

PubMed1997

Management of vestibular schwannomas (acoustic neuromas): auditory and facial nerve function after resection of 120 vestibular schwannomas in patients with neurofibromatosis 2.

OBJECTIVE: Vestibular schwannomas (VSs) affect young patients with Neurofibromatosis 2 (NF-2) and cause very serious problems for hearing, facial expression, and brain stem function. Our objective was to determine a therapy concept for the right timing and indication of neurosurgical therapy. METHODS: In 1000 consecutive VS resections, 120 tumors in 82 patients with NF-2 were surgically treated by the same surgeon (MS) at the Department of Neurosurgery at Nordstadt Hospital from 1978 to 1993. The mean age of the patients was 27.5 years. Sixty tumors were surgically treated in 41 male patients, and 60 tumors were surgically treated in 41 female patients. Bilateral tumor resection was performed in 38 patients (76 operations, after previous partial surgery in 15 cases elsewhere), and unilateral operations were performed in 44 patients, 5 of whom had undergone ipsi- or contralateral surgery that was performed elsewhere. The operative and clinical findings are evaluated and compared with the data of patients without NF-2. RESULTS: In 105 cases, complete tumor resections were achieved. In 15 cases, deliberate subtotal resections were performed. These were for brain stem decompression in 4 cases and for hearing preservation in the last hearing ear in 11 cases, with successful preservation in 8 of the 11. Pre- and postoperative hearing rates were higher in male than in female patients (70% in male versus 65% in female patients before surgery and 40.5 versus 31%, respectively, after surgery). Hearing was preserved in 29 of 81 ears (36%). The rate of preservation was 24% in cases of large tumors and 57% in cases of small tumors (<30 mm). Twenty-one of 82 patients (26%) were bilaterally deaf before surgery. Twenty-five patients had uni- or bilateral hearing after surgery (i.e., 41 % of those with preoperative hearing or 30.5% of the whole group). Anatomic facial nerve preservation was achieved in 85%. The facial nerve was reconstructed intracranially at the cerebellopontine angle by sural grafting in 17 cases and by hypoglossal-facial reanimation in 5. Two deaths occurred 1 and 3 months postsurgically as a result of malignant tumor growth with brain stem dysfunction and respiratory problems. In summary, for patients with NF-2, the presentation ages are lower, tumor progression is faster, the chances of anatomic and functional nerve preservation are lower, the chances of good outcomes are best when surgery is performed early and when there is good preoperative hearing function, and the danger of sudden hearing loss is higher. The chances and danger often differ from side to side among individual patients. CONCLUSION: The indication and the timing of tumor resections are in some respects different from normal VS handling and are dependent on the tumor extension and related necessity of brain stem decompression and on the auditory function. As an optimal goal, completeness of resection with functional cochlear nerve preservation is formulated, and as an acceptable compromise, subtotal microsurgical resection with functional cochlear nerve preservation in the last hearing ear is suggested.

Adolescent↗

PubMed1997

Management of vestibular schwannomas (acoustic neuromas): the value of neurophysiology for evaluation and prediction of auditory function in 420 cases.

OBJECTIVE: From 1978 to 1993, 1000 vestibular schwannomas were operated on at the Department of Neurosurgery at Nordstadt Hospital. The goal was to improve the chances of hearing preservation by recording auditory brain stem responses (ABRs). ABRs can be used for preoperative classification of cochlear nerve impairment and for prediction of the chances of hearing preservation. PATIENTS AND METHODS: In addition to the previously described audiometric testing, the patients underwent perioperative and intraoperative bilateral ABR recording at 100-dB condensation and rarefaction click stimulation. The classification system of five types of ABRs, as presented before, is based on the presence and on the latencies of Waves I, III, and V, with a special emphasis on Wave III's representing the activity of the first brain stem nuclei within the auditory pathway. According to an analysis of 420 preoperative ABRs, in case of a preoperative Type 1 or 2, the rate of hearing preservation is 80%. DISCUSSION: In the case of good clinical and audiometric hearing, a severely deteriorated ABR is mostly an indicator of severe nerve compression and adhesion by the tumor. In view of subsequently reported experiences with intraoperative ABR monitoring, the value of the presented system emphasizing the importance of Wave III is stressed and discussed with other views in the literature. The criteria presented here are not designed for recognition of retrocochlear disease but aim for evaluation of the state of the auditory nerve and its perspective. CONCLUSION: By the presented classification of ABR Type B1 through B5, preoperative prediction of the likelihood of hearing preservation is improved.

Adult↗

PubMed1997

Surgical management of meningiomas originating in Meckel's cave.

OBJECTIVE: To define the difference of meningiomas that originate in the area of Meckel's cave (MC) (primary MC meningiomas) in regard to the different surgical approaches and postoperative results. METHODS: A retrospective analysis of all meningiomas involving the cranial base displayed 21 cases of meningiomas originating in MC (primary MC meningiomas). These cases were classified according to the tumor extension in four different types: Type I, tumors mainly confined to MC; Type II, MC meningiomas with extension into the middle fossa; Type III, MC meningiomas with extension into the posterior fossa; and Type IV, MC meningiomas with extension into both middle and posterior fossae. RESULTS: Trigeminal neuralgia resolved in all cases in this series, despite tumor type. Trigeminal hypesthesia showed postoperative improvement only in Type III MC meningiomas. In Types I and III, total removal without further morbidity was frequently achieved. Cavernous sinus infiltration, especially in Types II and IV, limited (in some cases) the extent of tumor extirpation. CONCLUSION: Types I, II, and III MC meningiomas have a good prognosis. In most cases, very good outcomes are achieved. Radical tumor removal can usually be achieved without further morbidity and with postoperative improvement of the preexisting symptoms, especially in Types I and III MC meningiomas. On the contrary, Type IV MC meningiomas are usually only subtotally resected. Surgery in such cases may carry a high risk of additional morbidity, especially with regard to the IIIrd, IVth, and VIth cranial nerves. The postoperative outcome regarding facial pain in cases of all tumor types is usually very good. Trigeminal hypesthesia may persist after tumor removal in the majority of cases.

Adolescent↗

PubMed1997

Surgical management of craniopharyngiomas: a review.

Craniopharyngiomas are uncommon benign intracranial tumors that still represent a task in management. Controversy exists concerning the treatment of choice for these tumors. Radical surgery, subtotal resection combined with radiotherapy, or primary irradiation are the frequent treatment modalities. Although an increasing number of reports have appeared stressing the role of primary radiation for these tumors, radical surgery still represents the treatment of choice in most cases, since craniopharyngioma is a benign tumor and many affected patients are at a young age. In this article the authors review different aspects of pathology, clinical presentation, radiology, and management of the craniopharyngiomas. Common surgical approaches are described and both preoperative and postoperative management are outlined.

Craniopharyngioma↗

PubMed1997

Diagnosis of root avulsions in traumatic brachial plexus injuries: value of computerized tomography myelography and magnetic resonance imaging.

Surgical management and prognosis of traction injuries of the brachial plexus depend on the accurate diagnosis of root avulsion from the spinal cord. Myelography, computerized tomography (CT) myelography, and recently magnetic resonance (MR) imaging have become the main radiological methods for preoperative diagnosis of cervical root avulsions. Most of the previous studies on the accuracy of CT myelography and MR imaging studies have correlated the radiological findings with the extraspinal surgical findings at brachial plexus surgery. Surgical experience shows that in many cases extraspinal findings diverge from intradural determinations. Consequently, only correlation with the intradural surgical findings will allow assessment of the factual accuracy of CT myelography and MR imaging studies. In a prospective study, 135 cervical roots (C5-8) were evaluated by CT myelography and/or MR imaging and further explored intradurally via a hemilaminectomy. The accuracy of the preoperative CT myelography-based diagnosis in relation to the intraoperative findings was 85%. On the other hand, MR imaging demonstrated an accuracy of only 52%. The most common reasons for false-positive or false-negative findings were: 1) partial rootlet avulsion; 2) intradural fibrosis; and 3) dural cystic lesions. Computerized tomography myelography scans using 1- to 3-mm axial slices prove to be the most reliable method to evaluate preoperatively the presence of complete or partial root avulsion in traumatic brachial plexus injuries. Because extradural judgment of cervical root avulsion can be unreliable, accurate assessment of intraspinal root avulsion enormously simplifies the decision concerning the choice of donor nerves for transplantation and/or neurotization during brachial plexus surgery.

Adolescent↗

PubMed1997

Treatment of syringomyelia associated with arachnoid scarring caused by arachnoiditis or trauma.

The authors conducted a retrospective study of 107 patients treated for syringomyelia associated with arachnoid scarring between 1976 and 1995 at the Departments of Neurosurgery at the Nordstadt Hospital in Hannover, Germany, and the University of California in Los Angeles, California. Twenty-nine patients have not been surgically treated to date because of their stable neurological status. Seventy-eight patients with progressive neurological deficits underwent a total of 121 surgical procedures and were followed for a mean period of 32 (+/- 37) months. All patients demonstrated arachnoid scarring at a level close to the syrinx. In 52 patients the arachnoid scarring was related to spinal trauma, whereas 55 had no history of trauma and developed arachnoid scarring was a result of an inflammatory reaction. Of these, 15 patients had undergone intradural surgery, eight had suffered from spinal meningitis, three had undergone peridural anesthesia, and one each presented with a history of osteomyelitis, spondylodiscitis, and subarachnoid hemorrhage. No obvious cause for the inflammatory reaction resulting in arachnoid scarring could be ascertained for the remaining 26 patients. The postoperative neurological outcome correlated with the severity of arachnoid pathology and the type of surgery performed. Shunting of the syrinx to the subarachnoid, pleural, or peritoneal cavity was associated with recurrence rates of 92% and 100% for focal and extensive scarring, respectively. Successful long-term management of the syrinx required microsurgical dissection of the arachnoid scar and decompression of the subarachnoid space with a fascia lata graft. This operation stabilized the preoperative progressive neurological course in 83% of patients with a focal arachnoid scar. For patients with extensive arachnoid scarring over multiple spinal levels or after previous surgery, clinical stabilization was achieved in only 17% with this technique.

Adult↗

PubMed1997

Direct brainstem recording of auditory evoked potentials during vestibular schwannoma resection: nuclear BAEP recording. Technical note and preliminary results.

The usefulness of intraoperative monitoring in cerebellopontine angle surgery should be improved by obtaining faster and stronger brainstem auditory evoked potential (BAEP) responses. A new technique of direct recording at the brainstem has been developed, which is applicable to all tumor sizes. By placing a retractor with electrodes attached to its tip at the cerebellomedullary junction, the authors have recorded BAEP amplitudes that are 10 times greater than those recorded using the conventional technique. Only small sampling numbers (64-256 recordings) are required and are obtained in 5 to 15 seconds. The technique has been applied successfully in 34 patients who underwent vestibular schwannoma resections. It has also been tested in patients with intrameatal-extrameatal meningiomas and in those with vascular compressive disorders; there have been no false results. The advantages of this new technique are: 1) identification of BAEP components is easier and faster; 2) reliable BAEP responses are obtained in some cases in which conventional BAEP responses are lost or severely deformed; and 3) BAEP response deterioration and improvement are recognized earlier than would occur using the conventional technique. This last advantage provides the surgeon with a useful warning at a stage of surgery at which BAEP changes are still temporary and can be reversed. This method is different from other trials of intradural BAEP recordings in three respects: its use is not limited to particular tumor sizes; there is no interference with the surgical process; and, most important, the obtained responses correlate well with those of conventional BAEP responses, probably because the recording site is in the vicinity of the anterior cochlear nucleus. In conclusion, the chances of useful monitoring feedback with adequate adaptation of the microsurgical strategy are improved considerably.

Cochlear Nerve↗

PubMed1997

Proliferation potential and histological features in neurofibromatosis 2-associated and sporadic meningiomas.

The authors compared the histological appearance and proliferation potential of 35 meningiomas in patients with neurofibromatosis 2 (NF2) and 30 sporadic meningiomas in age- and gender-matched patients without NF2. The NF2 meningiomas showed more mitotic figures (p < 0.001) and nuclear pleomorphism (p = 0.003) than the sporadic meningiomas; however, the incidence of meningothelial, fibroblastic, and transitional subtypes occurred equally in both groups. The proliferation potential was significantly higher in the 35 meningiomas removed from 23 patients with NF2 than in the 30 sporadic meningiomas removed in the 30 patients without NF2 (mean MIB-1 labeling indices: 2.5 vs. 1.75, p = 0.0147). The higher proliferation potential of the NF2 meningiomas may reflect differences in molecular biology between sporadic and NF2 meningiomas and may be related to an earlier onset, multiplicity, and more aggressive behavior of NF2 tumors.

Adolescent↗

PubMed1997

Surgical reconstruction of the musculocutaneous nerve in traumatic brachial plexus injuries.

Over the last 16 years, 345 surgical reconstructions of the brachial plexus were performed using nerve grafting or neurotization techniques in the Neurosurgical Department at the Nordstadt Hospital, Hannover, Germany. Sixty-five patients underwent graft placement between the C-5 and C-6 root and the musculocutaneous nerve to restore the flexion of the arm. A retrospective study was conducted, including statistical evaluation of the following pre- and intraoperative parameters in 54 patients: 1) time interval between injury and surgery; 2) choice of the donor nerve (C-5 or C-6 root); and 3) length of the grafts used for repairs between the C-5 or C-6 root and the musculocutaneous nerve. The postoperative follow-up interval ranged from 9 months to 14.6 years, with a mean +/- standard deviation of 4.4 +/- 3 years. Reinnervation of the biceps muscle was found in 61% of the patients. Comparison of the different preoperative time intervals (1-6 months, 7-12 months, and > 12 months) showed a significantly better outcome in those patients with a preoperative delay of less than 7 months (p < 0.05). Reinnervation of the musculocutaneous nerve was demonstrated in 76% of the patients who underwent surgery within the first 6 months postinjury, in 60% of the patients with a delay of between 6 and 12 months, and in only 25% of the patients who underwent surgery after 12 months. Comparison of the final outcome according to the root (C-5 or C-6) that was used for grafting the musculocutaneous nerve showed no statistical difference. Furthermore, statistical analysis (regression test) of the length of the grafts between the donor (C-5 or C-6 root) nerve and the musculocutaneous nerve displayed an inverse relationship between the graft length and the postoperative outcome. Together, these results provide additional information to enhance the functional outcome of brachial plexus surgery.

Adolescent↗

PubMed1996

Meningiomas involving the parasellar region.

The authors report on 180 cases of meningiomas involving the parasellar region, which have been surgically treated between 1978 and 1993. Most of the tumors originated in the middle cranial fossa (66%). Half of the patients had visual deficits, and palsy of the eye movements was observed in 25% of the cases. Depending on the tumor origin and extension, the surgical approach was chosen. Total tumor resection varied very much, depending mostly on the tumor extension, and the pattern of growth. The overall total resection (Simpson I-II) was 57%. The postoperative results were good in 77% of the cases, and surgical mortality was 3%.

Adolescent↗

PubMed1996

Surgical results of spinal meningiomas.

We report on 94 spinal meningiomas in 88 patients operated between September 1977 and August 1994 which were followed for up to 13 years (mean 24 +/- 35 months). Complete tumour resection led to postoperative improvement of every preoperative deficit or symptom. En plaque, recurrent, anterior, and low thoracic or lumbar meningiomas were likely to be resected incompletely. Partial tumour removal, arachnoid scarring, primary dural suture, recurrent meningiomas, and male sex were independent factors predisposing to clinical recurrence. Cauterization instead of resection of the tumor matrix was not associated with a higher recurrence rate.

Adolescent↗

PubMed1996

Meningiomas of the cerebellopontine angle.

Meningiomas of the cerebellopontine angle (CPA) represent a clinically and surgically interesting entity. The opportunity of complete surgical excision and the incidence of impairment of nerval structures largely depend on the tumour biology that either leads to displacement of surrounding structures by an expansive type of growth or to an enveloping of nerval and vascular structures by an en plaque type of growth. As the origin and the direction of growth are very variable, the exact tumour extension in relation to the nerval structures and the tumour origin can be identified sometimes only at the time of surgery. Out of a series of 230 meningiomas of the posterior skull base operated between 1978 and 1993, data of 134 meningiomas involving the cerebellopontine angle are presented. There were 20% male and 80% female patients, age at the time of surgery ranging from 18 to 76 years, on the average 51 years. The clinical presentation was characterized by a predominant disturbance of the cranial nerves V (19%), VII (11%), VIII (67%) and the caudal cranial nerves (6%) and signs of ataxia (28%). 80% of the meningiomas were larger than 30 mm in diameter, 53% led to evident brainstem compression or dislocation and 85% extended anteriorly to the internal auditory canal. Using the lateral suboccipital approach in the majority of cases and a combined presigmoidal or combined suboccipital and subtemporal approaches in either sequence in 5%, complete tumour removal (Simpson I and II) was accomplished in 95% and subtotal tumour removal in 5%. Histologically the meningiotheliomatous type was most common (49%) followed by the mixed type (19%), fibroblastic (16%), psammomatous (7%), hemangioblastic (7%) and anaplastic (2%) types. Major post-operative complications were CSF leakage (8%) requiring surgical revision in 2% and hemorrhage (3%) requiring revision in 2%. While the majority of neurological disturbances showed signs of recovery, facial nerve paresis or paralysis was encountered in 17%, and facial nerve reconstruction was necessary in 7%. Hearing was preserved in 82% with improvement of hearing in 6%. The variability of tumour extension, the implications and limitations for complete surgical excision are discussed along with the experiences from the literature.

Adolescent↗

PubMed1996

Management of petroclival meningiomas: a critical analysis of surgical treatment.

Treatment of petroclival meningiomas have been a matter of discussion in neurosurgery. Since the advent of microsurgery, and with development of new skull base approaches more recently, the treatment of these tumours has become standardised, and the post-operative results considerably improved. However, potential complications have been related with the surgical removal of these lesions. The authors describe their experience and summarise the major reports of the literature on this subject.

Adolescent↗

PubMed1996

Spinal chordomas--results of treatment over a 17-year period.

Among a series of 511 spinal tumours treated in the Department of Neurosurgery at the Nordstadt Hospital in Hannover, Germany, between September 1977 and August 1994, 23 operations for spinal chordomas in 9 patients (3 females, 6 males) were performed. After an average period of 7 +/- 12 months (2 weeks to 5 years) patients presented at an average age of 45 +/- 17 years with pain (68%), gait ataxia (14%), motor weakness (9%) or sphincter disturbances (9%). A complete resection was achieved in 11 operations and a subtotal tumour removal in 12 instances. After subtotal removal, 5 tumours were treated postoperatively using local high dose radiotherapy (60-70 Gy). Overall, every chordoma recurred with the passage of time unless en-bloc resection of the tumour had been performed. The recurrence-free interval tended to be longer after radiotherapy. Analysis of postoperative results revealed a significant positive effect of radiotherapy for motor function, pain, Karnofsky score, and survival. In conclusion, en-bloc resection should be performed whenever localization and extension of the tumour allow one to do so. Surgery should be followed by local high dose radiotherapy.

Chordoma↗

PubMed1996

The surgical treatment of Chiari I malformation.

A retrospective study was undertaken on 133 patients with a Chiari I malformation treated within the last 16 years at the Departments of Neurosurgery at the Nordstadt Hospital Hannover, Germany, and the University of California, Los Angeles, U.S.A. Ninety-seven patients presented with symptoms related to accompanying syringomyelia and 4 with associated syringobulbia. They underwent 149 surgical procedures and were followed for a mean of 39 +/- 52 months. A decompression at the foramen magnum was performed in 124 patients, while 22 of those with syringomyelia were treated by shunting (7 syringosubarachnoid shunts, 15 syringoperitoneal or -pleural shunts), and 3 by ventriculoperitoneal shunts for hydrocephalus. Except for ventriculoperitoneal shunting, at least a short-term decrease in size of an associated syrinx was observed for all procedures in the majority of cases. However, no long-term benefit was observed for syrinx shunting operations. The best clinical long-term results were obtained with decompression of the foramen magnum in patients with (86% free of a clinical recurrence) and without syringomyelia (77% free of a clinical recurrence). We advise against syrinx shunting, a large craniectomy, and obex plugging which are associated with higher recurrence rates. Instead, surgery should consist of a small craniectomy, opening of the dura, archnoid dissection to establish normal cerebrospinal fluid (CSF) outflow from the 4th ventricle, and a fascia lata dural graft.

Adult↗

PubMed1996

The neuroimaging and clinical spectrum of neurofibromatosis 2.

Neurofibromatosis 2 (NF2) is an autosomal dominant disease predisposing to multiple tumors of the central and peripheral nervous system. Bilateral vestibular schwannomas are the hallmark of the disease. To define the clinical spectrum of the disease, we performed gadolinium-enhanced magnetic resonance imaging of the brain and spine as well as neurological, dermatological, and ocular examinations in 48 patients with NF2 diagnosed with the National Institutes of Health diagnostic criteria. Patients were ascertained from patient workshops and publications and from referral as a result of vestibular schwannoma surgery. Vestibular schwannomas were found in 46 patients (96%, 43 bilateral and 3 unilateral), spinal tumors were found in 43 (90%), posterior subcapsular cataracts were found in 30 (63%), meningiomas were found in 28 (58%), and trigeminal schwannomas were found in 14 (29%). The presenting symptoms included hearing loss or tinnitus in 15 patients (31%), multiple or nonspecific symptoms in 15 (31%), skin tumors in 12 (25%), and ocular symptoms in 6 (13%). When the complete spine was imaged, spinal tumors were more common in patients with NF2 than has previously been reported. This is a noteworthy finding, because spinal tumors are a major cause of NF2 morbidity and mortality.

Adolescent↗

PubMed1996

Surgical results for meningiomas of the craniocervical junction.

OBJECTIVE: We have undertaken a retrospective analysis of 38 patients who were operated on for 40 meningiomas of the craniocervical junction between September 1977 and August 1995 to determine which factors influenced resectability, complications, and postoperative outcomes. METHODS: Radiological examinations, clinical data, and operation notes were evaluated, and additional follow-up information was obtained from outpatient examinations, telephone calls, and questionnaires. RESULTS: Four groups could be distinguished according to dural attachment as follows: 1) 15 spinocranial meningiomas originated from the spinal canal and extended intracranially; 25 craniocervical meningiomas of intracranial origin were divided into 2) meningiomas of the lower clivus (10 patients with 11 tumors), 3) lateral meningiomas (11 patients with 12 tumors), and 4) posterior meningiomas (2 patients). Standard midline or lateral suboccipital approaches with opening of the foramen magnum and laminectomy of the involved cervical segments were sufficient for the great majority of tumors. In seven instances only, drilling the posterior third of an occipital condyle was needed. Twelve of 15 spinocranial meningiomas and 13 of 25 craniocervical meningiomas could be removed totally. One patient underwent ventriculoperitoneal shunting only. With a rate of 63% of totally removed and 30% of subtotally removed meningiomas in this region, we observed clinical recurrences for two patients only. Complications were encountered in 30% of patients, predominantly with recurrent and/or infiltrative or en plaque meningiomas. Whereas motor weakness and gait ataxia tended to improve postoperatively, cranial nerve deficits usually remained unaltered. CONCLUSION: The relationship of the tumor to neighboring structures, i.e., the vertebral artery in particular, determines its resectability. We recommend using extreme caution with recurrent or en plaque meningiomas and tumors associated with extensive arachnoid scarring.

Adolescent↗

PubMed1996

Xenon/CT CBF measurements as valuable diagnostic tool in a case of bilateral occlusive cerebrovascular disease associated with intracranial aneurysm.

A patient with the coincidental occurrence of a right internal carotid artery (ICA) stenosis and asymptomatic ipsilateral infraclinoidal ICA aneurysm is presented. CBF measurements including testing of the cerebrovascular reserve capacity (CRC) demonstrated a compromise of cerebral blood flow (CBF) within the anterior circulation of the affected side. We treated the patient in one operation by aneurysm clipping and subsequent carotid endarterectomy (CEA). 10 months later she presented with an occlusion of the contralateral ICA. CBF measurements showed sufficient resting flow and CRC on both sides. One year later repeat measurements disclosed a lowered resting CBF and diminished CRC on the affected side. Extracranial/Intracranial (EC/IC) artery bypass improved both symptoms and CBF/CRC values. The authors propose to treat symptomatic ICA stenosis and concurrent silent ipsilateral intracranial aneurysms at once if the patient is eligible for aneurysm surgery. CBF measurements should be performed before surgery. In a medically compromised patient carotid endarterectomy alone appears to be justifiable. In cases of symptomatic aneurysm and concurrent ICA stenosis a CEA can be added to aneurysm clipping to improve the hemodynamic situation for a better postoperative management. Xenon/CT investigations are suitable to provide important cerebral blood flow information. Together with angiography and clinical judgment it allows to identify patients with hemodynamic insufficiency. These are suitable candidates for an operative procedure to augment cerebral blood flow and to improve symptoms.

Blood Flow Velocity↗