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D Awasthi

Publications and source records attributed to D Awasthi.

14 recordsLinked to original sources
PubMed2001

Surgical anatomy of the C-2 pedicle.

OBJECT: The goal of this anatomical study was to investigate the surgical and radiographic anatomy of the C-2 pedicle in relation to transpedicular screw placement in occipitocervical stabilization and to establish anatomical guidelines for the placement of C-2 pedicle screws. METHODS: The C-2 pedicles in 10 cadaveric spines were evaluated using both computerized tomography (CT) scanning and manual measurements. The specimens were scanned; the mediolateral and rostrocaudal angulations of each pedicle were measured, with the midline sagittal plane and the inferior endplate of the C-2 facet, respectively, as references, and values were recorded in 1 degrees increments by using a digital goniometer. The height, width, and length of the pedicles were also measured on the CT scans. Based on these measurements in conjunction with direct visualization of the C-2 pedicle through the C 1-2 interlaminar space pedicle screws were then placed. The distances from the screw entry point to the midline, C2-3 joint line, and the medial aspect of the vertebral artery were also measured. Repeated CT scanning was then performed to assess screw placement. The average pedicle height, width, and length measured 9.1 mm, 7.9 mm, and 16.6 mm, respectively, and the medial, inclination and rostrocaudal angulation averaged 35.2 degrees and 38.8 degrees, respectively. The cortex of the pedicle was not violated in any of the 20 cadaveric specimens. CONCLUSIONS: Adequate preoperative imaging studies in conjunction with direct visualization of the C-2 pedicle make transpedicular fixation safe and effective.

Bone Screws↗
PubMed2001

Gunshot wounds to the neck.

Gunshot wounds to the neck are diagnostically and therapeutically challenging cases. We report such a case with vascular and neurologic injuries and describe the therapeutic options. Initial treatment is aimed at hemodynamic stabilization. Zone II neck injuries are managed selectively, and physical examination alone may dictate emergency surgical exploration. Spinal cord injury must be suspected and assessed clinically, as well as by computed tomography and angiography. Deteriorating or stable neurologic status and cord compression by bullet or bone fragments require surgical decompression. Improving neurologic status may be managed conservatively. In gunshot wounds to the neck, treatment should be individualized and multidisciplinary.

Adult↗
PubMed2000

Ossification of the ligamentum flavum as a cause of myelopathy in North America: report of three cases.

Myelopathy caused by ossification of the ligamentum flavum is a rare condition in North America. The authors describe three patients whose myelopathy was attributed to posterior cord compression warranting laminectomy to decompress the cervical spine (in one patient) and the thoracic spine (in two patients). The spinal computed tomographic scan (especially after myelography) can be instrumental in guiding the management of this condition.

Aged↗
PubMed1999

Far lateral transcondylar approach: dimensional anatomy.

OBJECTIVE: The far lateral extension of the classic suboccipital craniectomy has been found to reduce the depth of the field and improve the angle of surgical perspective to the ventrolateral clivus. The goal of the present study is to determine and compare the dimensions of the far lateral transcondylar approach with the suboccipital craniectomy. METHODS: Ten cadaveric specimens were used to study the anatomy at the foramen magnum (FM), occipital condyle (OC), and vertebral artery. The distances from the posterior midline of the FM to the medial and lateral borders of the OC were measured. The distance of the vertebral artery from the transverse foramen of C1 to its dural entry and the distance from the dural entry to the posteroinferior cerebellar artery were measured. The amount of OC removal that was necessary to expose the contralateral jugular tubercle was determined. A reference line was constructed from the posterior margin of the FM to the border of the OC. From this line, the angle of surgical approach provided by each exposure was measured. RESULTS: The mean distance of the vertebral artery from the transverse foramen of C1 to its dural entry was 22+/-3 mm (standard deviation), and the distance from the dural entry to the posteroinferior cerebellar artery was 17+/-8 mm. The distance from the posterior midline of the FM to the medial border of the OC was 27+/-0.5 mm; the distance from the posterior midline of the FM to the lateral border of the OC was 40+/-0.4 mm; and the long axis of the OC was 30+/-0.4 mm. The amount of OC removal to expose the contralateral jugular tubercle without brainstem retraction was 17+/-1 mm. The angle of surgical approach versus the reference line decreased from 88+/-2 degrees with the suboccipital craniectomy alone to 47+/-2 degrees for the far lateral transcondylar exposure (P < 0.001). This angle decreased an average of 2.4 degrees per millimeter of OC removal. CONCLUSION: Understanding the dimensions of the craniovertebral junction has clear implications for surgery in this area. If a lesion may be approached through a perpendicular exposure, the suboccipital craniectomy alone may be sufficient. Additional exposure of the ventrolateral clivus without brainstem retraction requires condylar removal. A more limited condylar removal than the 17 mm described in this report may be adequate if the entire 47-degree angle is not needed.

Cephalometry↗
PubMed1998

The pathogenesis of arteriovenous malformations: insights provided by a case of multiple arteriovenous malformations developing in relation to a developmental venous anomaly.

OBJECTIVE AND IMPORTANCE: Developmental venous anomalies (DVAs) are common anomalies of intracranial venous drainage that may occur in conjunction with other cerebral vascular malformations. The present case raises important questions regarding the association between anomalous venous drainage patterns and the development of arteriovenous malformations (AVMs). CLINICAL PRESENTATION: We present the case of a 24-year-old man with small AVMs fed by the superior cerebellar artery that drained directly into a large DVA of the cerebellum. INTERVENTION: The patient was managed conservatively and returned 10 years later with recurrent symptoms. A repeat angiogram demonstrated spontaneous thrombosis of the previously documented AVMs; however, new AVMs at a different site that was also fed by the superior cerebellar artery and drained into the same DVA had appeared. The AVMs were completely embolized, and the DVA was left intact. CONCLUSION: Recently, increasing attention has focused on the possible importance of venous outflow disturbance and venous hypertension in the pathogenesis and pathophysiology of AVMs. The potential mechanisms for this association and the implications of the present case are discussed, and the pertinent literature is reviewed.

Adult↗
PubMed1998

Skull-base trauma: neurosurgical perspective.

Trauma to the cranial base can complicate craniofacial injuries and lead to significant neurological morbidity, related to brain and/or cranial nerve injury. The optimal management involves a multidisciplinary effort. This article provides the neurosurgeon's perspective in management of such trauma using a 5-year retrospective analysis of patients sustaining skull-base trauma. The salient features of anterior and middle skull-base (temporal bone) trauma are summarized, and the importance of frontal basilar trauma as well as brain injury is evident. With these injuries, all cranial nerves (except 9 to 12) are at risk; the olfactory nerve and the facial nerve are the first and second, respectively, to sustain injuries. This retrospective analysis provides a better understanding of cranial base trauma and its management. It emphasizes the multifaceted nature of such trauma and the need to recognize anterior skull-base complications, including cerebrospinal fluid leak and brain injury.

Adult↗
PubMed1997

Oxidative stress following traumatic brain injury in rats.

BACKGROUND: Free radicals may be involved in the pathophysiology of traumatic brain injury (TBI) through oxidative damage of neurovascular structures. Endogenous antioxidants, such as ascorbate and alpha-tocopherol, may play a critical role in combating these oxidative reactions and their oxidized products can serve as an important index of oxidative stress. METHODS: We used electron spin resonance (ESR) spectroscopy and in vivo spin trapping (reaction of an organic compound with free radical species) to detect the possible generation of free radicals after TBI. Injury was inflicted by a weight drop technique over the head (5.7 kg-cm). Rats were intravenously infused with either 1 mL, 0.1 M of the spin trap, alpha-phenyl-N-tert-butyl nitrone (PBN), or an equivalent volume of saline immediately before TBI or sham-injury. Animals were divided into four groups: (1) Group I: PBN-infused sham-injured, (2) Group II: PBN-infused injured, (3) Group III: saline-infused sham-injured, and (4) Group IV: saline-infused injured. Additional groups of saline-infused uninjured, saline-infused, and PBN-infused injured animals were used for histopathology. Sixty minutes after TBI or sham-injury, rats were again anesthetized and decapitated. The brains were removed within 1 minute, homogenized, and extracted for lipids. The extracts were analyzed by ESR spectroscopy. Brain ascorbic acid (AA) concentration was determined spectrophotometrically, using the ascorbate oxidase assay. RESULTS: No PBN spin adduct signals (indicating trapped free radical species) were visible 60 minutes after TBI. All groups of rats showed an ascorbyl free radical signal. The ascorbyl signal intensity (AI) was, however, significantly higher in the injured rats, while the brain (AA) was significantly reduced. In addition, the ratio of AI/AA, which eliminates the effect of variable ascorbate concentrations in the brain, was also significantly higher in the injured animals. CONCLUSIONS: We conclude that 60 minutes following TBI there was a significantly increased level of oxidative stress in the brain. This may reflect formation of free radical species with subsequent interaction with ascorbate (antioxidant) during the 60 minute period. The lack of PBN spin adduct signals 1 hour after TBI may indicate that free radical generation is time dependent and might be detectable earlier or later than the 60 minute period.

Animals↗
PubMed1994

Posterior cervical fusion with methylmethacrylate, wire, and bone: technical note.

Surgical stabilization of non-neoplastic spinal lesions with methylmethacrylate and wire remains a controversial issue. In this report we offer a method of posterior cervical arthrodesis that combines using midline wire and acrylic with a lateral bony fusion. This construct allows for immediate as well as long-term stability. The technique is simple and safe, requires no special instrumentation, and is also easily extended to include the occipital bone. Rigid postoperative external immobilization is not required.

Adult↗
PubMed1994

Distal cervical internal carotid artery stenosis.

This report describes a case of distal cervical internal carotid artery (ICA) occlusive lesion managed by saphenous interposition vein graft after exposure of the ICA up to the skull base. The skull base approach described herein emphasizes the mobilization of the mandible without mandibular osteotomy or disarticulation. Instead, the stylomandibular and stylosphenoidal ligaments are resected to allow mandibular mobilization. In addition, the distal ICA lesion represented a form of diffuse intimal thickening without any plaque formation. This required the resection of the thickened, stenotic segment and reconstruction of the distal cervical ICA with a saphenous interposition graft. The surgical management implications of diffuse intimal thickening are discussed.

Case Reports↗
PubMed1992

Anterior cervical vertebrectomy and interbody fusion. Technical note.

This report discusses the authors' technique in performing anterior cervical vertebrectomy and interbody fusion for multilevel cervical disease. The technique is performed with a high-speed drill and bone-bank fibular strut graft. After decompression of the cervical canal, ledges are made in the intact vertebral bodies to create a rectangular bed for safe seating of the bone graft. The bone-bank fibular strut graft is a feasible alternative to autograft. The simplified and safe nature of this procedure reduces postoperative morbidity as well as the length of hospital stay.

Bone Transplantation↗
PubMed1991

Coagulation changes after an experimental missile wound to the brain in the cat.

Platelet studies (total number and platelet aggregation) and coagulation assays (fibrinogen, factor VIII, and anti-thrombin III) were performed on systemic arterial blood of four control and four experimental adult cats that sustained a penetrating missile injury to the brain. Among the brain-wounded, a significant decrease in the total number of platelets and aggregates occurred 120 minutes after injury. Fibrinogen levels decreased significantly in the brain-wounded animals by 240 minutes after injury and continued declining until the end of the 6-hour experiment. No significant changes occurred in factor VIII and antithrombin III levels in wounded as compared with control animals. These results indicate that blood coagulation factors are altered following a missile wound to the brain. These alterations may, occasionally, lead to clinically manifested bleeding disorders, specifically disseminated intravascular coagulation. Thus, early analysis and control of the coagulation system in the brain-wounded patient should be considered to prevent and treat bleeding disorders in the setting of penetrating head injury.

Analysis of Variance↗
PubMed1991

Cerebral amyloid angiopathy presenting as multiple intracranial lesions on magnetic resonance imaging. Case report.

Cerebral amyloid angiopathy is recognized as an important cause of spontaneous intracerebral hemorrhage in the elderly normotensive patient. Magnetic resonance (MR) imaging characteristics of this disease entity are rarely mentioned in the literature. The MR imaging findings of an elderly normotensive patient presenting with an acute spontaneous intracerebral hemorrhage secondary to amyloid angiopathy are reported and a brief review of amyloidosis is presented.

Aged↗
PubMed1991

Neuromuscular hamartoma (benign "triton" tumor) of the brachial plexus. Case report.

Neuromuscular hamartoma (choristoma) or benign "triton" tumor is a very rare peripheral-nerve tumor composed of mature nerve fibers and well-differentiated striated muscle fibers. Only seven cases have been reported in the literature. A new case of this rare entity is described in a 36-year-old white woman with a recurrent left supraclavicular mass in the brachial plexus area. Unlike the previous cases, this patient had continued to have proliferation of her tumor since childhood, requiring total resection in adulthood. It is concluded that total resection of these tumors should be attempted at initial diagnosis. The histogenesis of these tumors remains unclear. They may represent proliferation of neuroectodermal-derived or limb mesodermal tissue in the elements of a peripheral nerve.

Adult↗