Assessment of 3D-TOF-MRA at 3.0 Tesla in the characterization of the angioarchitecture of cerebral arteriovenous malformations: a preliminary study.

BACKGROUND: The characterization of brain arteriovenous malformation (AVM) angioarchitecture remains rewarding in planning and predicting therapy. The increased signal-to-noise ratio at higher field strength has been found advantageous in vascular brain pathologies. PURPOSE: To evaluate whether 3.0T time-of-flight (TOF) magnetic resonance angiography (MRA) is superior to 1.5T TOF-MRA for the characterization of cerebral AVMs. MATERIAL AND METHODS: Fifteen patients with AVM underwent TOF-MRA at 3.0T and 1.5T and catheter angiography (DSA), which was used as the gold standard. Blinded readers scored image quality on a four-point scale, nidus size, and number of feeding arteries and draining veins. RESULTS: Image quality of TOF-MRA at 3.0T was superior to 1.5T but still inferior to DSA. Evaluation of nidus size was equally good at 3.0T and 1.5T for all AVMs. In small AVMs, however, there was a tendency of size overestimation at 3.0T. MRA at 3.0T had increased detection rates for feeding arteries (+21%) and superficial (+13%) and deep draining veins (+33%) over 1.5T MRA. CONCLUSION: 3.0T TOF-MRA offers superior characterization of AVM angioarchitecture compared with 1.5T TOF-MRA. The image quality of MRA at both 3.0 and 1.5T is still far from equal to DSA, which remains the gold standard for characterization of AVM.

Injection therapy of lumbar facet syndrome: a prospective study.

BACKGROUND: Chronic low back pain remains a major health problem. Facet joint injection therapy is an easy to perform therapeutic option. However, few prospective studies use a standardized protocol to investigate injection therapy. The aim of our study was to evaluate quantity and duration of clinical improvement after this protocol, and to identify the best time for additional repetitive injection therapy. MATERIALS AND METHODS: Thirty-nine patients (21 men, 18 women; mean age 55.2 years [range, 29-87 years]) with lumbar facet syndrome were treated with injection using a standardized protocol (prednisolone acetate, lidocaine 1%, phenol 5%) under fluoroscopic control. Follow-up was based on a specially designed questionnaire. Analysis included MacNab criteria, visual analogue scale, and pain disability index. RESULTS: Reduction of pain was found up to 6 months after treatment. The outcome was assessed excellent or good by 62% (24 patients) of the patients after 1 month, by 41% (16 patients) after 3 months, and by 36% (14 patients) after 6 months. There was no influence of age, body mass index, or previous lumbar spinal surgery on improvement after treatment. There were no severe side effects. Short-lasting self limiting mild side effects were found in 26% (increased back pain, numbness, heartburn, headache, allergy). CONCLUSION: Facet joint injection therapy using a standardized protocol is safe, effective, and easy to perform. The clinical effect is limited, and we recommend repetitive injection according to this protocol after 3 months.

Bleeding complications after endovascular therapy of cerebral arteriovenous malformations.

BACKGROUND AND PURPOSE: Intracerebral hemorrhages after embolization of arteriovenous malformations (AVMs) are the most dreaded complications of this well-established therapy. Apart from the known risk factors, our center noticed a high incidence of complications during postinterventional monitoring in medical intensive care units (ICUs) and stroke units. MATERIALS AND METHODS: We report 125 consecutive interventions performed on 66 patients by using flow-dependent microcatheters and n-butyl cyanoacrylate as the embolic agent. Postinterventional intensive care monitoring was performed in an interdisciplinary operative ICU, a stroke unit, or a medical ICU. Patients were compared with regard to bleeding complications, AVM morphology, embolization result, postinterventional monitoring, and demographic factors. RESULTS: Intracerebral hemorrhages occurred in 7 patients. Significant differences in outcome were found between 66 patients monitored in the interdisciplinary operative ICU from medical ICU or stroke unit. This was also true when adjusted for age and extent of AVM reduction by using exact logistic regression. A partial AVM reduction of >60% was a considerable risk factor for hemorrhage (odds ratio [OR] = 18.8; 95% confidence interval [CI] [1.341, not available]. Age was also an essential risk factor. An age difference of 10 years leads to an OR of 2.545 (95% CI [1.56, 7.35]). DISCUSSION: A considerable AVM reduction in one session appears to increase the risk of hemorrhage technically. This suggests a distribution of the interventions in many partial steps.

Comparison of metric analysis of spinal structures, exemplarily of the ligamentum flavum, obtained with CT and MRI.

PURPOSE: Comparison of metric analysis of spinal structures, exemplarily of the ligamentum flavum, obtained with computed tomography (CT) (soft tissue window and bone window) and magnetic resonance imaging (MRI) (T1 and T2 weighted images). MATERIAL AND METHODS: Forty-six lumbar ligamenta flava of 46 patients (25 women and 21 men) were examined at a Somatom Plus 4 (Siemens, Erlangen, FRG) and at a 1.5 T clinical scanner (Magnetom Vision, Siemens, Erlangen, FRG). Two independent neuroradiologists measured the thickness of the ligamenta flava in mm. Statistics included Pearson's correlation coefficient and the intra-class correlation coefficient. RESULTS: Mean values did not differ significantly. The correlation coefficients varied between 0.69 and 0.98. The best correlation occurred comparing the same techniques in different windowing and weighting (CT: r = 0.98; MRI: r = 0.95). Correlating different techniques the combination of CT bone window and T1 weighted images presented the best result (r = 0.75). CONCLUSIONS: Because of the excellent correlation between the examined techniques CT as well as MRI can equally be used to measure distances of spinal structures.

Giant intracerebral choroid plexus calcification.

While small calcifications of the choroid plexus are frequent, a large, single intracerebral calcification originating from the choroid plexus is rare. This report presents a 27-year-old woman who was admitted because of right temporal headache which had persisted for months. There was no neurological deficit. Computed tomography demonstrated a mass of calcium density measuring approximately 3 x 3 x 4 cm in the right temporal region, extending to the temporal skull base and to the rostral edge of the petrous bone. At surgery a very hard, poorly vascularised tumour originating from the choroid plexus of the temporal horn of the right lateral ventricle was completely removed. Histological workup yielded the diagnosis of a markedly calcified choroid plexus with no indication of neoplasia or inflammation. Physiological intracranial calcifications resulting from local tissue dystrophy are usually incidental. In the case presented here, a large intracerebral choroid plexus calcification was detected in a patient presenting with episodes of severe headache. The potential pathogenetic mechanism is discussed.

[Changes of the fat/water ratio in the erector trunci muscle in patients with lumbar disc herniation: a comparative study with 1H-MRS]. / Veränderungen des Fett/Wasser-Quotienten im Musculus erector trunci bei Patienten mit lumbalem Bandscheibenvorfall: eine vergleichende.

PURPOSE: To evaluate whether metabolic changes of the erector trunci muscle in patients with lumbar disc herniation can be detected with proton magnetic resonance spectroscopy ( (1)H-MRS). MATERIALS AND METHODS: In 10 patients with lumbar disc herniation and 16 healthy volunteers, proton spectra were obtained from the erector trunci muscle and analyzed for fat-water ratio. The axial images were evaluated for the degree of atrophy of the erector trunci muscle. The muscular tissue was histopathologically examined in 2 patients. RESULTS: The examination was well tolerated by all patients and volunteers and all acquired spectra could be analyzed. Patients with lumbar disc herniation have a significantly increased fat-water ratio of 0.19 compared to 0.09 in the control group, with a p-value of 0.003. This result correlates well with the bioptical findings of increased intracellular lipid deposits and lipomatous transformation of the muscle parenchyma. CONCLUSION: (1)H-MRS is a useful method to detect metabolic changes in lumbar back musculature and, as a non-invasive technique, might play a role in monitoring exercise in lumbar disc herniation. It can be expected that muscle regeneration will be shown as precisely as muscle degeneration. This hypothesis, however, remains to be proven.

Chronic lumbar epidural haematoma presenting with acute paraparesis.

Chronic spinal epidural haematomas are very rare and have been reported to occur only in the lumbar region. They usually become symptomatic through radicular pain or neurogenic claudication. The epidural bleeding is thought to originate from a rupture of an epidural vein due to a sudden increase in intra-abdominal pressure or due to trauma. The patient reported on here developed acute paraparesis about 8 weeks after a mild fall on the buttocks. MRI showed a spinal epidural mass located dorsolaterally at the level of L3-L5. The mass was surgically removed. Histological and immunohistological studies disclosed an organised haematoma. The clinical, radiological and intra-operative features of this case are described, and the relevant literature is analysed.

Clinical evaluation of a new intracranial pressure monitoring device.

BACKGROUND: Continuous monitoring of intracranial pressure (ICP) still plays a key role in the management of patients at risk from intracranial hypertension. Numerous ICP-measuring devices are available. The aim of the present study was to investigate the clinical characteristics and the magnetic resonance imaging (MRI) compatibility of the recently developed Neurovent-P(REHAU AG+CO, REHAU, Germany) ICP monitoring device. METHOD: In a prospective two-center study, a total of 98 patients with severe head injury, subarachnoid haemorrhage, intracerebral haemorrhage, and non-traumatic brain edema underwent intraparenchymal monitoring of ICP using the Neurovent-P. A control group comprising 50 patients underwent implantation of the Camino-OLM-110-4B ICP monitor. The zero drift of the probes was determined before and after the ICP recording period. Technical and medical complications were documented. The MRI compatibility of the Neurovent-P ICP probe was investigated by evaluating artifacts caused by the probe, probe function and temperature changes during MRI, and probe movement caused by the magnetic field. FINDINGS: The mean zero drift was 0.2+/-0.41 mmHg (maximum 3 mmHg) for the Neurovent-P ICP probes and 0.4+/-0.57 mmHg (maximum 12 mmHg) for the Camino-OLM-110-4B ICP probes. No significant correlation was identified between the extent of zero drift following the removal of the probes and the length of monitoring. Intraparenchymal haemorrhage spatially related to the probe occurred in 1 out of 50 (2%) patients with a Camino-OLM-110-4B probe and in 1 out of 98 (1%) with a Neurovent-P. Damage of the probe due to kinking or overextension of the cable or glass fiber occurred in 4 of the 50 (8%) Camino-OLM-110-4B ICP probes and in 5 of the 98 (5%) Neurovent-P probes. On T2-weighted MR images, the Neurovent-P ICP probe induced only small artifacts with very good discrimination of the surrounding tissue. On T1-weighted MR images, there was a good imaging quality but artifact-related local disturbances in signal occurred. There was no temperature change in the Neurovent-P probe and in the surrounding brain tissue during MR imaging. INTERPRETATION: The Neurovent-P ICP measuring system is a safe and reliable tool for ICP monitoring. Handling of the Neurovent-P system is safe when performed properly.

Impact of brain shift on intraoperative neurophysiological monitoring with cortical strip electrodes.

BACKGROUND: Intraoperative neurophysiological monitoring has become the standard procedure for locating eloquent regions of the brain. Such continuous electrical stimulation of motor pathways is usually applied by means of flat silicon-embedded electrodes placed directly on the motor cortex. However, shifting of the silicon strip on the cortical surface as well as electrode displacement due to brain shift underneath the electrode can lead to inaccurate recordings not directly caused by intraoperative impairment of the motor cortex or the motor pathways. METHOD: This prospective study was conducted to quantify cortical brain shift during open cranial surgery and to assess its impact on electrode positioning in 31 procedures near the precentral gyrus. Three groups of different lesion volumes were distinguished. Movement of the cortex between opening of the dura and completion of tumor removal as well as cortical electrode shifting were digitally measured and analyzed. FINDINGS: Cortical surface structures evidenced a significantly larger shift (up to 23.4 mm) in comparison to the electrode strips (up to 4.2 mm) in lesions with a volume of over 20 ml. Cortex shifting highly correlated with lesion volume, whereas strip electrode movement was almost unidirectional and did not differ significantly among the three groups. However, the way they were placed (completely on the cortex vs. partly underlying or overlapping the craniotomy borders) affected the magnitude of their intraoperative displacement. As a consequence, 3 of the 31 cases (9.3%) showed a significant change in the recorded motor responses due to intraoperative dislocation of the stimulating electrode. INTERPRETATION: Changes in the location of cerebral structures due to intraoperative brain shift may exert a marked influence on intraoperative neurophysiological monitoring if cortical strip electrodes are used. Therefore, long-term monitoring of the central region requires continuous checking of the position of stimulating electrodes and, if necessary, correction of their location.

Spontaneous bilateral chronic subdural haematoma of the posterior fossa. Case report and review of the literature.

INTRODUCTION: Chronic subdural haematomas of the posterior fossa in adults without a history of trauma are very rare. To our knowledge, only 15 cases have so far been reported in the literature, including those with anticoagulation therapy. A case of spontaneous bilateral infratentorial chronic subdural haematoma associated with anticoagulation therapy in an alive adult is presented and the relevant literature is reviewed. CASE REPORT: A 70 year old female presented with progressive dizziness, vertigo and gait ataxia. She was on anticoagulation therapy for heart disease. Neuro-imaging revealed bilateral infratentorial subdural masses. The subdural masses were suspects for chronic subdural haematomas by neuroradiological criteria. Because of the progressive symptomatology, the haematomas were emptied through burrhole trepanations. Chocolate-colored fluid, not containing clotted components, gushed out under great pressure. The source of bleeding could not be identified. The patient recovered well from surgery, but died 4 months later shortly after admission to another hospital from heart failure. DISCUSSION: The chronic subdural haematomas in this patient may have been due to rupture of bridging veins caused by a very mild trauma not noticed by the patient and possibly aggravated by the anticoagulation therapy. Infratentorial chronic subdural haematoma should at least be a part of the differential diagnosis in elderly patients with cerebellar and vestibular symptomatology even without a history of trauma.

Lumbar disc herniation in patients up to 25 years of age.

Retrospective analysis of 165 patients (105 males, 60 females) with a mean age of 21.2 years (range 14 to 25 years) of 6933 surgically treated patients from January 1987 to May 1999 focused on age and sex distribution, body mass, familial predisposition, trauma, histology, and clinical course. The incidence of herniated lumbar discs was 2.3% in patients aged up to 25 years. A valid family history was obtained in 121 patients and a positive history was found in 82 of these patients (67.8%). The patients had a higher body mass index compared to a group of individuals with a similar age structure. Radiography demonstrated bony changes in 124 patients (75.2%), primarily attributable to postural deformities such as scoliosis. The condition of the bony structures seems to be more important than the condition of the disc tissue in the occurrence of this disease in young patients.

Biodegradable implants in neurosurgery.

BACKGROUND: Biodegradable materials have been used for osteosynthesis by orthopedic surgeons and craniomaxillofacial surgeons for many years. However, such materials are not yet widely used by neurosurgeons despite potential applications. This prospective study was undertaken to evaluate potential applications of biodegradable materials in neurosurgical interventions. METHODS: A total of 104 4-hole plates and 228 screws consisting of copolymer of poly-70 L/30 D,L-lactide were inserted for fixation of bone flaps in 8 patients and for reinsertion of laminoplasties at 28 levels in 16. The craniotomies were performed for removal of a brain tumour in 4 cases, for surgical management of an aneurysm or cerebral AVM in 2, and for treatment of craniocerebral trauma in another 2. Laminoplasties were performed at 25 levels for intraspinal hemangioblastomas in 15 patients. One patient with an ependymoma underwent 3-level laminoplasty. FINDINGS: One patient with severe head injury in whom the bone flap was re-implanted several months following the craniectomy, developed an aseptic necrosis of the bone flap, which had to be removed. Implant rejection was not observed. One patient suffered from mild local pain in the area of a biodegradeable screw in the frontal region following removal of a sphenoid wing meningeoma. None of the patients with laminoplasty showed signs of functional instability or spinal cord compression. Implant rejection was not observed. No delayed healing or infection occurred. Healing was not delayed and no infections occurred. INTERPRETATION: The results encourage further use of biodegradable materials for the described applications. Additional studies will be performed to investigate the usefulness of biodegradable devices in neurosurgery and to obtain long-term results.

Surgical treatment of spinal hemangioblastomas.

BACKGROUND: The routine use of magnetic resonance imaging (MRI) in recent years for the diagnostic assessment of the spinal column and especially for screening patients with von Hippel-Lindau (vHL) disease has shown that spinal hemangioblastomas (sHBs) are more common than assumed so far. Since most sHBs are thus discovered while they are still asymptomatic, especially in vHL disease, the question arises whether and when these tumors should be treated. The present article reports the results of the surgical treatment of sHBs using the protocol described below and compares them to the course in a control group of patients with conservatively treated sHBs. PATIENTS AND METHODS: A total of 30 sHBs were treated microsurgically in 15 patients. Hemangioblastoma-associated cysts were merely opened in 14 cases, drained with the help of Teflon cotton in 2 of these cases, and not opened in 4 instances. Laminoplasties were performed with insertion of absorbable, MRI-compatible microosteosynthesis plates. Perioperatively, all patients were administered methylprednisolone according to the NASCIS (National Acute Spinal Cord Injury Study) scheme, and sensory evoked potentials were monitored intra-operatively in all cases. Nine patients in whom the course of primarily conservative treatment of a total of 17 asymptomatic sHBs was documented served as controls. The follow-up time was 7 to 51 months (mean 20) after surgery and 10 to 51 months (mean 21) in the control group. FINDINGS: Preoperative HB-associated pareses showed transient postoperative deterioration (n = 5). The other accompanying neurological deficits improved in 6 HBs and remained unchanged in all other HBs (n = 19), of which 16 had been asymptomatic before surgery. In the control group, 6 HBs (in 6 different patients) became permanently symptomatic despite subsequent surgical treatment according to the study protocol. INTERPRETATIONS: With the new diagnostic tools now available, microsurgical removal of spinal hemangioblastomas has a low morbidity rate, suggesting that surgical treatment should be considered even for asymptomatic sHBs in certain circumstances.

Transcranial Doppler ultrasonography as a screening technique for detection of a patent foramen ovale before surgery in the sitting position.

BACKGROUND: Venous air embolism has been reported to occur in 23-45% of patients undergoing neurosurgical procedures in the sitting position. If venous air embolism occurs, a patent foramen ovale (PFO) is a risk factor for paradoxical air embolism and its sequelae. Preoperative screening for a PFO is therefore recommended by some investigators. The reference standard for identifying a PFO is contrast-enhanced transesophageal echocardiography (c-TEE). Contrast-enhanced transcranial Doppler ultrasonography (c-TCD) and contrast-enhanced transthoracic echocardiography (c-TTE) are noninvasive alternative methods, but so far there are no studies as to their diagnostic validity in neurosurgical patients. METHODS: The sensitivity and specificity of c-TCD and c-TTE in detecting a PFO were determined in a prospective study using c-TEE as the reference standard. Preoperative c-TCD, c-TTE, and c-TEE studies were performed during the Valsalva maneuver after intravenous echo-contrast medium (D-Galactose, Echovist-300, Schering AG, Berlin, Germany) was administered in 92 consecutive candidates (47 men and 45 women; mean age, 51 yr; range, 25-72 yr) before neurosurgical procedures in the sitting position. RESULTS: A PFO was detected in 24 of the 92 patients (26.0%) using c-TEE. c-TCD correctly identified 22 patients, whereas c-TTE only correctly identified 10. This corresponds to a sensitivity of 0.92 for c-TCD and 0.42 for c-TTE. The negative predictive value was 0.97 for c-TCD compared with 0.83 for c-TTE. The prevalence of a PFO in patients with a posterior fossa lesion was 27%, and in the group with cervical disc herniation was 24% as detected by c-TEE. The incidence of intraoperative venous air embolism was 35% in cases of cervical foraminotomy and 75% in posterior fossa surgery as detected by c-TEE. CONCLUSIONS: c-TCD is a highly sensitive and highly specific method for detecting a PFO. Because c-TCD is noninvasive, it may be more suitable than c-TEE for routine preoperative screening for a PFO. C-TTE is not reliable in detecting a PFO.

Intracranial haemorrhage following lumbar myelography: case report and review of the literature.

We describe a subacute intracranial subdural haematoma following lumbar myelography. This rare but potentially life-threatening complication has been reported both after lumbar myelography and following lumbar puncture for spinal anaesthesia. We review 16 previously reported cases of intracranial haemorrhage following lumbar myelography, and discuss the pathogenesis. In all reported cases post-puncture headache was the leading symptom and should therefore be regarded as a warning sign.

Intraoperative microvascular Doppler ultrasonography in cerebral aneurysm surgery.

OBJECTIVES: Outcome of surgical treatment of cerebral aneurysms may be severely compromised by local cerebral ischaemia or infarction resulting from the inadvertent occlusion of an adjacent vessel by the aneurysm clip, or by incomplete aneurysm closure. It is therefore mandatory to optimise clip placement in situ to reduce the complication rate. The present study was performed to investigate the reliability of intraoperative microvascular Doppler ultrasonography (MDU) in cerebral aneurysm surgery, and to assess the impact of this method on the surgical procedure itself. METHODS: Seventy five patients (19 men, 56 women, mean age 54.8 years, range 22-84 years) with 90 saccular cerebral aneurysms were evaluated. Blood flow velocities in the aneurysmal sac and in the adjacent vessels were determined by MDU before and after aneurysm clipping. The findings of MDU were analysed and compared with those of visual inspection of the surgical site and of postoperative angiography. Analysis was also made of the cases in which the clip was repositioned due to MDU findings. RESULTS: A relevant stenosis of an adjacent vessel induced by clip positioning that had escaped detection by visual inspection was identified by Doppler ultrasonography in 17 out of 90 (18.9%) aneurysms. In addition, Doppler ultrasound demonstrated a primarily unoccluded aneurysm in 11 out of 90 (12.2%) patients. The aneurysm clip was repositioned on the basis of the MDU findings in 26 out of 90 (28.8%) cases. In middle cerebral artery (MCA) aneurysms, the MDU results were relevant to the surgical procedure in 17 out of 44 (38.6%) cases. Whereas with aneurysms of the anterior cerebral artery significant findings occurred in only five of 32 cases (15.6%; p<0.05). The clip was repositioned on the basis of the MDU results in 18 out of 50 (36%) aneurysms in patients with subarachnoid haemorrhage (SAH) grade I-V compared with only eight out of 40 (20%) aneurysms in patients without SAH (p<0.05). CONCLUSIONS: MDU should be used routinely in cerebral aneurysm surgery, especially in cases of MCA aneurysms and after SAH. Present data show that a postoperative angiography becomes superfluous whenever there is good visualisation of the "working site" and MDU findings are clear.

Brain tumor surgery in geriatric patients: a critical analysis in 44 patients over 80 years.

BACKGROUND: The decision of whether to operate on brain tumors in elderly patients has not been made easier despite diagnostic and therapeutic advances facilitating their diagnosis. Little is known about the outcome of brain tumor surgery in patients 80 years or older probably because the number of these patients, although increasing, is still small. METHODS: The results of brain tumor surgery in 44 patients aged 80-86 years (mean age 83 years) were analyzed to determine which factors are relevant in the evaluation of the operative risk. The following parameters were analyzed with regard to the outcome: tumor volume, location, histopathology, preoperative condition, and concomitant diseases. RESULTS: At discharge 19 patients (43%) had improved while 14 (32%) remained unchanged. Nevertheless, the overall results were unsatisfactory in 10 patients (23%), of whom 5 died in hospital. Tumor location, volume, and histopathology did not correlate with the outcome. The preoperative cerebrovascular condition and the existence of multiple concomitant diseases were clearly the determining factors for the outcome. CONCLUSIONS: These results indicate that patients with life-threatening tumors or those causing persistent and intolerable brain dysfunction suffering from symptomatic cerebrovascular atherosclerosis as well as from multiple treatment requiring concomitant diseases did definitely not benefit from surgery.

Neoplasm of endolymphatic sac origin: clinical, radiological and pathological features.

This paper reports on a 55-year-old female who had undergone middle ear surgery 12 years previously and was admitted with a 6-months history of unilateral hearing loss and facial weakness. MRI and CT demonstrated a space-occupying lesion arising from the temporal bone and extending into the posterior fossa. Treatment consisted in complete tumour removal. Temporal and mastoid bone destruction associated with typical histological features led to the diagnosis of neoplasm of endolymphatic sac origin. Clinical, histological, radiological and intra-operative features of these rare tumours are described and discussed. The pertinent literature is reviewed.

The use of direct intra-operative Doppler ultrasonography in carotid thromboendarteriectomy. A prospective study.

Large multicenter studies have recently provided long-term results substantiating the superiority of surgical as compared to conservative treatment for symptomatic and asymptomatic extracranial internal carotid stenoses of more than 70%. These results led to an increase in the frequency of thrombo-endarteriectomies. However, indications are limited by the peri-operative complication rate. This explains the need for intra-operative quality control. The present study compares the standard method of intra-operative quality control in carotid surgery, i.e., intra-operative angiography (IOA), with direct intra-operative Doppler ultrasonography (IDU). Thirty-four patients who underwent carotid thrombo-endarteriectomy (carotid TEA) for a symptomatic (n = 15) or asymptomatic (n = 19) carotid stenosis of more than 70% were submitted to both intra-operative IOA and IDU. The sensitivity and specificity of the two techniques were compared in the light of the intra-operative findings. IDU seems to be superior to IOA in the detection of vasospasm. IOA has a higher sensitivity in demonstrating minisaccules, which, however, are not therapeutically relevant. The other findings obtained with both methods were considered to be of equal value. There were no false negative results by IDU regarding therapeutically relevant findings. We therefore consider it advisable to apply IDU in every case of carotid TEA. IOA should be performed in patients with vessel changes detected by IDU.