Detection of clinically silent intracranial emboli ipsilateral to internal carotid occlusions during cerebral angiography.

OBJECTIVE: Embolic ischemic events have long been suspected to occur in the cerebral arteries distal to an ipsilateral occluded internal carotid artery (ICA). Documentation of microemboli by transcranial Doppler sonography during catheter angiography in patients with ICA occlusions provides objective evidence of such distal emboli. SUBJECTS AND METHODS: Seven patients undergoing carotid angiography were evaluated with transcranial Doppler sonography. Patients were also screened for ICA occlusions using carotid duplex sonography. In the seven patients, we saw five right ICA occlusions and two left ICA occlusions. Real-time visual and auditory confirmations of emboli were obtained by recognizing their specific spectral signatures and harmonic qualities. Routes of collateral flow were determined from angiography. Specific phases of the examination were correlated with embolic occurrences. RESULTS: Overall, emboli were seen during all phases of arteriography. In the individual patients, emboli were identified in one to four of the eight angiographic phases we defined. Most emboli occurred during catheter flushing and contrast injection rather than during wire and catheter manipulation. The emboli were detected in the middle cerebral artery distribution ipsilateral to the occluded ICA in all seven patients. Collateral flow patterns included, in four patients, external carotid artery-to-ICA collateral flow; in all seven patients, patent anterior communicating arteries; and in three patients, patent posterior communicating arteries. CONCLUSION: Emboli seen in middle cerebral arteries ipsilateral to occluded ICAs during cerebral angiography strongly indicate that emboli can occur distal to an occlusion. Our findings support the thought that emboli arising from sources proximal to an occluded ICA may reach the hemisphere distal to the occlusion, resulting in parenchymal ischemia or infarction.

Carotid transposition: another cause of wide retropharyngeal soft tissues.

OBJECTIVE: The purpose of this original report is to describe medial transposition of the common carotid arteries. This transposition may produce wide retropharyngeal soft tissues on lateral cervical radiographs. CONCLUSION: When common carotid arteries are transposed from their normal lateral positions into the retropharyngeal soft tissues, if vascular calcifications are present, this carotid abnormality is easily recognized on plain radiographs. Radiologists and clinical physicians should be aware that vascular transposition may be a benign cause of widening of the retropharyngeal soft tissues.

Silent cerebral microemboli occurring during carotid angiography: frequency as determined with Doppler sonography.

OBJECTIVE: The purpose of this study was to determine the frequency of occult cerebral embolic events during carotid angiography and the relationship of these events to different phases of the procedure. SUBJECTS AND METHODS: Fifteen patients undergoing carotid angiography were prospectively evaluated by using continuous transcranial Doppler monitoring. Realtime visual and auditory confirmations of emboli were accomplished by recognizing their specific spectral signature and harmonic quality. Specific phases of the examination, such as manipulation of the catheter and guidewire, flushing of the catheter, and injecting contrast material were documented and correlated with embolic occurrences. RESULTS: A total of 1100 embolic phenomena were detected in the middle cerebral artery during carotid angiography. Of these, 944 occurred during catheter flushing and injection of contrast material, and 156 occurred during catheter and wire manipulation. In each patient, more emboli occurred during catheter flushing and injection of contrast material than during manipulation of the catheter and guidewire. No gross neurologic sequelae occurred. CONCLUSION: Embolic phenomena occur frequently during all phases of uncomplicated cerebral angiography.

Intraoperative angiography and temporary balloon occlusion of the basilar artery as an adjunct to surgical clipping: technical note.

The direct surgical treatment of intracranial aneurysms is not always possible, especially in posterior circulation aneurysms. This is usually because of their complex anatomy and location next to the skull base and brain stem, where proximal vascular control is usually not attainable. Four patients at our institution underwent intraoperative transfemoral catheterization of the basilar artery with a nondetectable endovascular balloon for proximal control of the basilar artery. The flow control in the basilar artery was excellent and facilitated the surgery. Before surgery, each patient underwent the placement of a 10-cm 8-French femoral introducer sheath and were taken to the operating room where they were placed in a supine position and a subtemporal or pterional craniotomy was performed. After the initial exposure and before aneurysm manipulation, a nondetachable silicone balloon catheter was passed through an introducer catheter and was placed into the rostral basilar artery, using flow direction, microguidewires, and angiographic "road-mapping" techniques. In two patients, temporary basilar occlusion was used to collapse the aneurysm and to facilitate clip placement. In the third patient, intraoperative aneurysm rupture occurred and was controlled by temporary basilar artery occlusion. Using intraoperative angiography, complete aneurysm obliteration and vessel patency was confirmed in all four patients. All patients made a complete recovery except for initial postoperative third nerve palsies in three patients. This technique achieves intraoperative control of the basilar artery proximal to an aneurysm by the use of a nondetachable occlusive balloon in the basilar artery. An added benefit is the ease with which intraoperative angiography can be obtained in this context.(ABSTRACT TRUNCATED AT 250 WORDS)

Magnetic resonance characteristics of the LGM vena cava filter: technical note.

The LGM (Vena Tech) IVC filter is a recently introduced device for caval interruption. The magnetic resonance imaging safety and imaging characteristics of this filter were evaluated. The filter was proven to lack ferromagnetic properties. It was imaged with minimal artifact and no detectable motion in the magnetic field.

Coaxial needle technique for lumbar puncture in the morbidly obese patient.

The authors describe a method of enhancing the ease of lumbar puncture in the morbidly obese patient. In their experience, the coaxial needle technique shortens fluoroscopic and total procedure times when obtaining cerebrospinal fluid for laboratory analysis or when performing myelography.

Segmental cord atrophy. Unusual case report in an infant.

We describe an unusual case of paraplegia in infancy. Radiographs of the spine were unable to detect any anomalies. An MRI demonstrated segmental atrophy of the spinal cord.

Degenerative disease of the lumbar spine. Role of CT-myelography in the MR era.

One hundred patients with degenerative disease of the lumbar spine on whom both magnetic resonance (MR) and computed tomography (CT)-myelography were performed were reviewed. In one-third of the cases, the CT-myelogram provided additional useful information. This included definition of the extent of large disc herniations, demonstration of focal neural compression by small herniations, and clarifying abnormalities of the facets, including synovial cysts. These results should help to refine the indications for CT-myelography, which continues to be requested extensively.

MR recognition of posterior lumbar vertebral ring fracture.

Four cases of lumbar vertebral ring fracture, in which magnetic resonance (MR) was used, were reviewed. The MR features included (a) discontinuity and truncation of the posteroinferior vertebral body, (b) displacement of the avulsed low signal fragment, and (c) disk prolapse subjacent to the fragment. Recognition of these findings may eliminate the need for other diagnostic studies.

Acute tissue tear hemorrhages of the brain: computed tomography and clinicopathological correlations.

Tissue tear hemorrhages (TTHs) are often seen on high-resolution computed tomographic scans after closed head injury. Generally, TTHs have been thought to be visible manifestations of more severe forms of diffuse axonal injury and thus portend a poor prognosis. Computed tomographic scans from 600 patients with head injuries were reviewed; 48 (8%) were found to have TTHs. The clinical spectrum of TTHs was characterized. No direct relationship could be established between either the presence or the number of TTHs and the severity and/or outcome from the head injury in this group, except that patients with TTHs in both the brain stem and the corpus callosum uniformly had a poor outcome. Magnetic resonance imaging provided more sensitive information than computed tomography in evaluating TTHs.

Absent cord sign in acute spinal trauma.

Review of magnetic resonance imaging (MRI) findings in 100 patients suffering acute spinal trauma from 1985 to 1987 revealed four patients who had suffered thoracic spine fractures and acute subarachnoid hematomas. The spinal cord was not demonstrated on the T1-weighted sagittal MRI due to the similarities in signal intensity between the spinal cord and acute hemorrhage. Nonvisualization of the thoracic cord should not be presumed to be artifactual until subarachnoid hematoma is excluded.

The radiologic assessment of post-traumatic vertebral stability.

The stability of the vertebral column depends upon the integrity of the bones, ligaments, and joints. The vertebral column can be divided into three distinct anatomic zones: anterior, middle, and posterior. Disruption of any single zone does not produce instability. Disruption of two contiguous zones will, however, significantly decrease the load-carrying capability of the spine and result in instability. Five radiographic signs indicative of vertebral instability have been identified: (1) displacement implies injury to major ligamentous and articular structures; (2) a wide interlaminar space implies injury to the posterior ligamentous structures and the facet joints; (3) wide facet joints imply injury to the posterior ligamentous structures; (4) a disrupted posterior vertebral body line implies burst injury with disruption of anterior bony and posterior ligamentous structures; (5) a wide vertebral canal implies injury to the entire vertebra in the sagittal plane. Each of these signs indicates disruption of a major skeletal, ligamentous, or articular structure and the presence of only one is sufficient to establish a diagnosis of instability. These conclusions are based upon a study of 138 injuries observed in 125 patients.

Major cerebral vessels injury caused by a seatbelt shoulder strap: case report.

Major cerebral arterial injury may result from penetrating or blunt trauma. In blunt trauma, clinical suspicion of such injury may not be raised, especially if the cranial CT scan is negative. We report a case of a seatbelt shoulder strap to the neck resulting in injury to three major cerebral vessels as demonstrated by cerebral angiography. Although the initial cranial CT scans were negative, a cerebral infarction ultimately developed. The patient was managed conservatively and recovered most of her functions. The importance of clinical suspicion and cerebral angiography is stressed.

Hyperextension injuries of the cervical spine. Magnetic resonance findings.

Eleven patients with acute cervical hyper-extension injury underwent magnetic resonance examination. Magnetic resonance was particularly helpful in diagnosing both intrinsic cord contusion and extradural compression. When spinal cord compromise was present, surgery was undertaken without resort to myelography.

Occult occipital condyle fractures presenting as tumors.

Occipital condyle fractures can be easily overlooked on plain radiographic examinations of the head and cervical spine. This is especially true if such a fracture is not clinically suspected, since they are very rare fractures. Two patients presented with suspected tumors of the foramen magnum region. Both had old trauma and undiagnosed old fractures of the occipital condyle.

Patterns of high-speed impact injuries in motor vehicle occupants.

Trauma from high-speed motor vehicle accidents is a leading cause of death and disability. Most of these injuries could be prevented if the driver and occupants of motor vehicles wore seatbelts or used other restraining devices. The injuries produced when an unrestrained occupant of a motor vehicle is ejected from that vehicle or impacts on a hostile surface at high speed occur in a reproducible pattern. The types of injuries sustained by drivers and front seat passengers are different and specific enough to allow one to identify drivers and passengers with confidence. Because of severe life-threatening injuries to the central nervous system, and thoracic and abdominal viscera, other serious injuries may be overlooked. Knowledge of the mechanism of injury and the role of the victim (i.e., driver or passenger) should lead to the prompt radiographic evaluation of all areas at risk. Our findings are based on a study of 250 drivers and 250 front seat passengers involved in motor vehicle accidents. We found distinct common injury patterns and radiographic findings in drivers and front seat passengers.

Thoracic disc herniation versus spinal metastases: optimizing diagnosis with magnetic resonance imaging.

Thoracic disc herniation has been difficult to diagnose, both on clinical grounds and by conventional radiologic methods. This entity may masquerade as a neoplastic mass, particularly if there is a history of primary malignancy. Magnetic resonance imaging was able to establish the correct diagnosis in each of the four cases presented here.

The impact of magnetic resonance on the diagnostic evaluation of acute cervicothoracic spinal trauma.

From 1984 to 1987 magnetic resonance (MR) imaging was performed on 100 patients suffering acute spinal trauma. MR demonstrated one or more injuries to the cervicothoracic region in 31 patients. It displayed a spectrum of spinal cord injury ranging from mild compression and swelling to complete transection. MR was also useful in evaluating alignment at the cervicothoracic junction, in depicting ligamentous injury, in establishing the presence of disc herniation, and in identifying unsuspected levels of injury. We present a diagnostic algorithm that incorporates the role of MR in evaluating acute cervicothoracic spinal trauma and emphasizes the replacement of myelography by MR in the initial assessment of neurologic deficit.

Syringomyelia: myelography, computed tomography, and magnetic resonance imaging.

Seventeen patients with cervical spinal cord cavities were studied with myelography, postmyelographic computed tomography scanning, and magnetic resonance imaging. The three diagnostic techniques were compared for accuracy, patient comfort, and ease of procedure. Magnetic resonance imaging was the best diagnostic and most comfortable procedure. There is no need for myelography or postmyelographic computed tomography scanning for the evaluation of cervical syringomyelia.