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N A Martin

Publications and source records attributed to N A Martin.

At least 73 records · Page 4Linked to original sources
PubMed1994

Cerebral blood flow measurement in neurosurgical intensive care.

This article has addressed the rationale for the clinical measurement of CBF in the neuro-surgical ICU. The techniques that are currently available for measurement of CBF have been reviewed, and those that are particularly appropriate for ICU use have been highlighted. Several examples of the role of CBF monitoring in the management of ICU patients have been described, and these clinical situations are considered further in other articles in this issue regarding the management of patients with head injury and subarachnoid hemorrhage. These CBF monitoring techniques should be integrated with TCD and cerebral metabolism monitoring as described elsewhere in this issue. With further clinical experience and research and development in the area of neurosurgical critical care, CBF monitoring is almost certainly destined to become a routine and widely employed technique.

Blood Flow Velocity↗
PubMed1994

Critical care of patients with subarachnoid hemorrhage.

Critical care of a patient with SAH should focus on the prevention or immediate treatment of the common sequelae of this disorder that adversely affect outcome: vasospasm, rebleeding, hydrocephalus, seizures, and associated medical problems. The frequency of rebleeding can be lessened by early surgical or endovascular intervention. The extent of SAH on the CT scan can identify those patients at highest risk for vasospasm, and all patients must be closely monitored in the ICU with serial neurological examinations and transcranial Doppler studies. Regional CBF examinations and continuous EEG may also be helpful. Calcium channel blocking agents and volume expansion are recommended prophylatically for all patients. Aggressive hypertensive, hemodilutional, hypervolemic therapy (including pulmonary artery catheter placement) is indicated for symptomatic vasospasm. Transluminal angioplasty can be used in selected patients with vasospasm refractory to these measures. Hydrocephalus can occur in the days, weeks, or months following SAH and is treated effectively with external (acute hydrocephalus) or internal cerebrospinal fluid diversion. Seizures, which can cause intracranial and systemic hypertension, high cerebral metabolic demand, and delayed neurological injury, should be prevented with prophylactic use of anticonvulsants. In addition, early recognition and treatment of associated medical complications are critical. Novel endovascular approaches, meticulous surgical technique, and aggressive ICU care will undoubtedly lead to improved outcome following aneurysmal SAH.

Aneurysm, Ruptured↗
PubMed1994

The neurosurgical intensive care unit in an era of health care reform.

Health care reform, public concern, and managed care will create an environment that demands highly creative strategies to deliver quality care while reducing costs. Patient satisfaction and outcomes will take on a high priority. To meet this challenge, the neurosurgical ICU of the future will be designed with a patient-focused theme wherein the physical environment embodies healing and humanism. Services will be brought to the patient rather than the patient accommodating the system. Patients and families will be the directors of their own care. Staff and families will have access to a highly sophisticated clinical information system, and learning for staff at all levels will be a part of everyday life in the ICU. Unit management will be within a framework of shared governance wherein the power base is with the direct care givers, and decision and policy making happens at the point closest to the patient. Patient outcomes will be a result of a highly organized collaborative model that includes primary nursing, critical paths, and case management. Partnerships between nurses and unit support staff will create skill-mix changes that allow the nurse to spend less time on nonclinical unit maintenance-type functions and more time with the patient and family. This will have a positive fiscal impact as well as enhance patient satisfaction and outcomes.

Cost-Benefit Analysis↗
PubMed1993

The pathology of arteriovenous malformations of the brain treated by embolotherapy. II. Results of embolization with multiple agents.

Light microscopic and immunohistochemical examination was undertaken of intracranial arteriovenous malformations (AVMs) surgically resected from 18 patients, each of whom had undergone preoperative angiographic embolization with multiple agents. Distinct patterns of tissue reaction to these agents were noted, even when more than one substance was present in a vascular lumen. Avitene produced the mildest tissue response but resulted in relatively early endothelialization and recanalization. Cyanoacrylates were longer-lasting but associated with more acute and chronic (including granulomatous) inflammation and vessel wall changes. Polyvinyl alcohol foam/ethanol mixture had intermediate properties. Endothelial proliferation over embolization material was confirmed using immunohistochemical application of an antibody to cell proliferation-specific proteins. The significance of these findings for combined endovascular and surgical treatment of cerebral vascular malformations is discussed.

Adolescent↗
PubMed1993

Pediatric intracranial vascular malformations: evaluation of treatment results with color Doppler US. Work in progress.

To determine the value of color Doppler ultrasound (US) in the preoperative assessment and evaluation of treatment results in children with intracranial vascular malformations (VMs), the authors performed 36 color Doppler US studies in nine children who underwent endovascular embolization. Color flow imaging with spectral waveform analysis of feeding arteries, nidus, draining veins, and uninvolved cranial vasculature was performed, and correlation was made with other imaging findings. In most VMs, color Doppler US enabled the authors to map the lesion completely. Hemodynamic changes after embolization included improvement in blood supply to uninvolved portions of the brain and increase in caliber and flow of feeding vessels that were not occluded during embolization. Serial volume flow measurements were performed with Doppler US in major extracranial arteries. Success of embolization was indicated by substantial decrease of total carotid artery flow. Color Doppler US is a noninvasive modality that adds important imaging and hemodynamic data to those provided by angiography.

Cerebral Angiography↗
PubMed1993

The petrosal approach with hearing preservation.

Twenty-six patients with petroclival lesions were operated on via a petrosal approach designed to preserve hearing. The surgical pathology included 14 meningiomas, three chordomas, three epidermoid cysts, four vertebrobasilar aneurysms, and two pontine cavernous malformations. The approach allowed complete resection of 14 of 20 tumors and definitive treatment of all six vascular lesions. Complications included cerebrospinal fluid leakage in three patients, high-frequency sensorineural hearing loss in three, meningitis in one, and cranial nerve palsies (which were usually transient). This approach allows a wide exposure of the petroclival region with decreased operating distance. Cerebellar and temporal lobe retraction are minimized, dural sinus patency is maintained, and the inner ear structures are not sacrificed. The approach is suitable for neoplastic or vascular lesions involving the petroclival region, the ventral pons, or the basilar artery trunk. The surgical technique, indications, and neuro-otological considerations are discussed.

Adolescent↗
PubMed1993

Magnetoencephalographic localization of a language processing cortical area adjacent to a cerebral arteriovenous malformation. Case report.

In order to accurately estimate the risk of surgery for dominant perisylvian arteriovenous malformations, the topographical relationship of the lesion to language cortex must be determined. A case is presented in which a magnetoencephalographic (MEG) study was used to map preoperatively and noninvasively an intracortical source of speech-receptive cortex in a 25-year-old right-handed man with a dominant left temporal lobe arteriovenous malformation. The speech-evoked magnetic field was analyzed at 36 positions over the left hemisphere in response to presentations of the consonant-vowel syllables "da" and "ga." A topographical map of the magnetic component evoked at 110 msec after stimulus onset, which was negative going to the vertex in concurrent electrical recordings, was congruent with a superficial cortical neuronal current source. This source was displaced from that usually observed in normal individuals to tonal or click stimuli, being superior to the probable location of auditory cortex, and superior and anterior to the probable location of Wernicke's area as conventionally described. The MEG results were in accord with the determination of position of a language-processing cortical area as assessed by direct electrical stimulation of the cortex during surgery under local anesthesia, and by superselective Amytal (amobarbital) injection during angiography. The MEG recordings and exposed brain stimulation sites were coordinated by cranial measurements, skull x-ray landmarks, and angiographic anatomy. Investigations such as this, which compare MEG findings with those from established clinical procedures, are an essential step in determining the physiological and anatomical utility of magnetoencephalography for noninvasive clinical functional localization.

Adult↗
PubMed1993

True anatomical compartmentalization of the cavernous sinus in a patient with bilateral cavernous dural arteriovenous fistulae. Case report.

An unusual case of complete anatomical compartmentalization of the cavernous sinus in a patient with bilateral Type D cavernous dural arteriovenous fistulae is described. This anatomical anomaly isolated the anterior cavernous sinus and orbital venous system, which was primarily responsible for the patient's clinical presentation. The compartmentalization of the cavernous sinus also limited options for definitive endovascular therapy to a transvenous approach via the superior ophthalmic vein.

Adult↗
PubMed1992

Topographic mapping of somatosensory evoked potentials helps identify motor cortex more quickly in the operating room.

Median nerve somatosensory evoked potentials were recorded from exposed cerebral cortex during craniotomies. This technique is valuable when knowledge of the motor cortex location can influence surgical decisions about resection limits or biopsy sites. Two different recording techniques were compared: strips of electrodes and arrays of electrodes. The arrays recorded electrical potentials suitable for topographic mapping. We found that motor cortex could be identified more quickly when using the topographic mapping of SEPs from arrays. We conclude that topographic mapping of SEP from sensorimotor regions during craniotomies works well in general and can be done more quickly than the traditional electrode strip technique.

Adolescent↗
PubMed1992

Posttraumatic cerebral arterial spasm: transcranial Doppler ultrasound, cerebral blood flow, and angiographic findings.

Thirty patients admitted after suffering closed head injuries, with Glasgow Coma Scale scores ranging from 3 to 15, were evaluated with transcranial Doppler ultrasound monitoring. Blood flow velocity was determined in the middle cerebral artery (MCA) and the intracranial portion of the internal carotid artery (ICA) in all patients. Because proximal flow in the extracranial ICA declines in velocity when arterial narrowing becomes hemodynamically significant, the extracranial ICA velocity was concurrently monitored in 19 patients. To assess cerebral perfusion, cerebral blood flow (CBF) measurements obtained with the intravenous 133Xe technique were completed in 16 patients. Vasospasm, designated as MCA velocity exceeding 120 cm/sec, was found in eight patients (26.7%). Severe vasospasm, defined as MCA velocity greater than 200 cm/sec, occurred in three patients, and was confirmed by angiography in all three. Subarachnoid hemorrhage (SAH) was documented by computerized tomography in five (62.5%) of the eight patients with vasospasm. All cases of severe vasospasm were associated with subarachnoid blood. The time course of vasospasm in patients with traumatic SAH was similar to that found in patients with aneurysmal SAH; in contrast, arterial spasm not associated with SAH demonstrated an uncharacteristically short duration (mean 1.25 days), suggesting that this may be a different type of spasm. A significant correlation (p less than 0.05) was identified between the lowest CBF and highest MCA velocity in patients during the period of vasospasm, indicating that arterial narrowing can lead to impaired CBF. Ischemic brain damage was found in one patient who had evidence of cerebral infarction in the territories supplied by the arteries affected by spasm. These findings demonstrate that delayed cerebral arterial spasm is a frequent complication of closed head injury and that the severity of spasm is, in some cases, comparable to that seen in aneurysmal SAH. This experience suggests that vasospasm is an important secondary posttraumatic insult that is potentially treatable.

Adolescent↗
PubMed1992

Intracerebral hemorrhage due to dural arteriovenous malformations and fistulae.

Intracerebral hemorrhage is the most devastating complication of dural AVMs. The lesions most at risk are those located at the tentorial incisura and in the anterior cranial fossa. The more common dural AVMs located at the transverse-sigmoid sinus and cavernous sinus typically do not hemorrhage and more frequently present with insidious symptoms such as a cranial bruit, tinnitus, or headache. Angiographic appearance of pial draining veins or an intervening varix identifies those patients most at risk for bleeding. An aggressive clinical stance must be taken in this group of patients, with the goal being complete extirpation of the lesion, because any residual AVM can enlarge and recruit pial veins, thus increasing the chances of future hemorrhage. Hemorrhage, which frequently is massive, can be spontaneous or occur after endovascular embolization. When hemorrhage does occur, medical and surgical management must be immediately instituted to avoid secondary brain injury. Therapeutic options include surgery and embolization using particulate material or polymerizing glues, alone or in combination. Although surgery remains the most effective and versatile method for treating dural AVMs, endovascular therapy and stereotactic radiosurgery will likely play more significant roles in treating these lesions in the future.

Aged↗
PubMed1991

Middle cranial fossa transtemporal approach to the intrapetrous internal carotid artery.

Diseases involving the proximity of the internal carotid artery at the skull base require identification of this vessel in the temporal bone to gain vascular control for any maneuver in its vicinity. This article details the technique of surgical dissection and exposure of the internal carotid artery within the skull base through a transtemporal middle cranial fossa approach. The anatomic landmarks important in utilizing this procedure include the greater superficial petrosal nerve, the mandibular branch of the trigeminal nerve, and the middle meningeal artery. With this approach, the internal carotid artery can be followed throughout the carotid canal and beyond the formen lacerun to the region of the cavernous sinus. The indications and limitations of this procedure are described and several clinical applications are provided.

Journal Article↗
PubMed1991

Combined endovascular embolization and surgery in the management of cerebral arteriovenous malformations: experience with 101 cases.

The authors describe their experience with 101 cerebral arteriovenous malformations (AVM's) treated by endovascular embolization followed by surgical removal. Fifty-three patients presented with intracranial hemorrhage and 35 had seizures. Based on the classification of Spetzler and Martin, two AVM's were Grade I, 13 were Grade II, 26 were Grade III, 43 were Grade IV, and 17 were Grade V. Fifty-six AVM's were in the right hemisphere, 28 were in the left hemisphere, 12 were in the corpus callosum, and five involved the cerebellum. In 50 cases, presurgical obliteration of 50% to 75% of the AVM nidus was achieved by embolization, and in 31 cases this percentage increased to between 75% and 90%. In 97 (96%) patients, complete surgical removal of the AVM was obtained. Morbidity resulting from preoperative endovascular embolization was classified as mild in 3.9% of the cases, moderate in 6.9%, and severe in 1.98%. The death rate related to embolization was 0.9%. The immediate postsurgical morbidity was classified as mild in 5.9% of the cases, moderate in 10.8%, and severe in 5.9%. The overall long-term morbidity was mild in 5.9% of the cases, moderate in 6.9%, and severe in 1.98%. Two patients (1.98%) died due to intractable intraoperative hemorrhage and two (1.98%) as a result of postsurgical pulmonary complications.

Adolescent↗
PubMed1990

Isolated growth hormone deficiency associated with a giant arteriovenous varix.

A 6.5-year-old girl with short stature (height age, 3 years; bone age, 1.75 years) had isolated growth hormone deficiency. Preoperative computed tomography and magnetic resonance imaging demonstrated a large, well-demarcated, homogeneous mass above the dorsum sellae with a density consistent with flowing blood. Vertebral angiography showed a giant intracranial varix caused by an arteriovenous fistula that originated at the apex of the basilar artery. At operation, an aneurysm clip was placed at the origin of the fistula, and occlusion of the fistula was confirmed by intraoperative digital subtraction angiography. There were no permanent neurological sequelae. Despite shrinkage of the varix, demonstrated by follow-up computed tomography, growth hormone deficiency persisted postoperatively. Biosynthetic growth hormone therapy was initiated 6.5 months after surgery and resulted in a height increment of 8.2 cm after 9 months of treatment.

Basilar Artery↗
PubMed1990

Management of dural arteriovenous malformations of the anterior cranial fossa.

Eight patients with dural arteriovenous malformations (AVM's) of the anterior cranial fossa are presented, and the pertinent literature is reviewed. Unlike cases of dural AVM's in other locations, sudden massive intracerebral hemorrhage was the most frequent reason for presentation. Other symptoms included tinnitus, retro-orbital headache, and a generalized seizure. The malformations were supplied consistently by the anterior ethmoidal artery, usually in combination with other less prominent feeding vessels. The lesion's venous drainage was through the superior sagittal sinus via a cortical vein; in addition, in two cases a subfrontal vein drained the AVM. A venous aneurysm was encountered near the site of anastomosis with the dural feeder in most cases, and was found in all patients who presented with hemorrhage. The AVM was obliterated surgically in six patients, with favorable results achieved in five. One patient died postoperatively from a pulmonary complication. Because of their anatomy and proclivity for hemorrhage, these vascular malformations represent a unique group of dural AVM's. Surgical management of anterior fossa dural AVM's carries low morbidity, and is indicated when the lesions have caused hemorrhage or when there is an associated venous aneurysm.

Adult↗
PubMed1990

Intraoperative digital subtraction angiography and the surgical treatment of intracranial aneurysms and vascular malformations.

Intraoperative digital subtraction angiography using commercially available equipment was employed to confirm the precision of the surgical result in 105 procedures for intracranial aneurysms or arteriovenous malformations (AVM's). Transfemoral selective arterial catheterization was performed in most of these cases. A radiolucent operating table was used in all cases, and a radiolucent head-holder in most. In five of the 57 aneurysm procedures, clip repositioning was required after intraoperative angiography demonstrated an inadequate result. In five of the 48 AVM procedures, intraoperative angiography demonstrated residual AVM nidus which was then located and resected. In two cases intraoperative angiography failed to identify residual filling of an aneurysm which was seen later on postoperative angiography, and in one case the intraoperative study failed to demonstrate a tiny residual fragment of AVM which was seen on conventional postoperative angiography. Two complications resulted from intraoperative angiography: one patient developed aphasia from cerebral embolization and one patient developed leg ischemia from femoral artery thrombosis. This technique appears to be of particular value in the treatment of complex intracranial aneurysms and vascular malformations.

Angiography, Digital Subtraction↗