Gerald A. Grant

The utility of magnetic resonance imaging in evaluating peripheral nerve disorders

The evaluation of peripheral nerve injuries has traditionally relied primarily on information gained from the clinical history, physical examination, and electrodiagnostic testing. Taken together, all of this clinical and diagnostic information often allows one to determine the location and severity of the underlying peripheral nerve problem. However, it may not be sufficient in diagnosing a focal entrapment neuropathy superimposed upon a more generalized peripheral neuropathy; localizing a focal lesion along a long segment of nerve which may be difficult to assess accurately with electrodiagnostic sutdies; distinguishing early between an axonotmetic grade of injury, which can recover through axonal regeneration, and a neurotmetic grade which cannot and therefore may benefit from a surgical exploration and repair procedure; and noninvasively diagnosing and determining the surgical resectability of peripheral nerve mass lesions such as tumors. The goal of this review is to illustrate how standard and evolving magnetic resonance imaging techniques can provide additional information in dealing with some of these problems.

Evaluation and surgical management of peripheral nerve problems.

OBJECTIVE To illustrate how an understanding of the basic biological responses of peripheral nerves to injury is important in formulating a rational treatment plan. METHODS Peripheral nerve anatomy and physiology are described in a context that is relevant to understanding the different grades of peripheral nerve injury. Methods of evaluating and treating peripheral nerve injuries both medically and surgically are reviewed. Relevant scientific studies with potential clinical impact are also discussed. RESULTS The clinical symptoms, physical findings, and electrodiagnostic and imaging test results relevant to the diagnosis of peripheral nerve problems are reviewed. Conventional and new medical or surgical strategies in the management of peripheral nerve injuries and mass lesions are described. CONCLUSION The diagnosis and treatment of peripheral nerve injuries follow logically from an understanding of the biological responses of peripheral nerves after injury and during recovery.

Long‐term safety and efficacy of continuous intrathecal baclofen

Long-term continuous intrathecal baclofen (CITB) infusion is a treatment option used to manage otherwise intractable spasticity and is delivered via an implantable pump. The purpose of this single-center multidisciplinary review was to report on the long-term safety and efficacy of CITB in the treatment of 21 children with intractable severe spasticity of cerebral origin. Nineteen recipients had spastic quadriplegia and two had spastic diplegia. Seven recipients had level IV severity on the Gross Motor Functional Classification System and 14 had level V. Median age at implantation was 12 years (range 4 to 20). Fifteen recipients were male, 6 were female. Seventeen recipients were alive at the end of the follow-up period (31 to 78 months; mean 53, SD 4). The Ashworth scale showed a substantial decrease in spasticity in the upper and lower extremities at 6 months and at the most recent follow-up. The Gross Motor Function Measure and Pediatric Evaluation of Disability Inventory showed no functional change. Most treatment goals were at least partly achieved. Caregivers reported a reduction in use of oral medication for spasticity, and improvements in comfort, function, and ease of care. Caregiver satisfaction was high. During 80 recipient-years of pump operation, 153 treatment-associated adverse events occurred: 27 of these were device-related. There were four deaths unrelated to CITE, including one from acute pancreatitis. Our findings might assist in establishing patient selection criteria and treatment goals, improving patient follow-up, and monitoring adverse events.

Thrombotic, Infectious, and Procedural Complications of the Jugular Bulb Catheter in the Intensive Care Unit

OBJECTIVE An assessment of the thrombotic, infectious, and technical complications of continuous jugular bulb catheter monitoring in the intensive care unit (ICU) was made. METHODS Over a 1-year period, 44 patients suffering from traumatic brain injury, subarachnoid hemorrhage, or stroke received jugular bulb catheter monitoring in the ICU. They were followed for catheter insertion complications and the development of bacteremia. In 20 patients chosen randomly, an ultrasonographic evaluation was performed after removal of the catheter for an assessment of internal jugular vein thrombosis. RESULTS Of the 44 patients, 1 became bacteremic; the source was identified as a thoracostomy site. Among the complications related to the 44 catheter insertions, there were 2 instances of carotid artery puncture (4.5%), 1 misplaced catheter (thoracic placement), and 1 clinically insignificant hematoma. Of the 20 patients investigated with ultrasonography, 8 (40%) had nonobstructive, subclinical internal jugular vein thrombi after jugular bulb catheter monitoring (95% confidence interval, 19-61%). The median monitoring duration was 3 days (range, 1-6 d). No clinical factor was identified to be associated with thrombus formation. CONCLUSION We conclude the following: 1) the risk of bacteremia related to the jugular bulb catheter was negligible; 2) complications related to catheter insertion were rare and clinically insignificant; and 3) the incidence of subclinical internal jugular vein thrombosis after jugular bulb catheter monitoring is considerable. Although it is worthy to note this complication, no patient with a thrombus became symptomatic in the present series. The risk-benefit assessment of this monitoring technique must include consideration of subclinical thrombosis.

A new model of the blood-brain barrier : co-culture of neuronal, endothelial and glial cells under dynamic conditions

Developing in vitro blood-brain barrier (BBB) models that closely mimic the natural state is important for theoretical and practical applications, including drug development. We previously developed an in vitro BBB model based on co-culturing endothelial cells with glia in the presence of flow on hollow fiber tube culture substrates. We now report that this dynamic in vitro BBB (DIV-BBB) can be successfully used to co-culture differentiated serotonergic neurons in the presence of a BBB. These neurons demonstrated fluoxetine-sensitive serotonin (5HT) uptake and depolarization-induced release of [3H]5HT. Our results demonstrate that the DIV-BBB is a suitable model for culturing of neurons in a quasi-physiological microenvironment and in the presence of a high-resistance, stereoselective BBB.

Accuracy of continuous jugular bulb oximetry in the intensive care unit.

OBJECTIVE: To address the accuracy of a bedside jugular bulb oxygen saturation (S j O 2 ) catheter monitor (Baxter-Edwards, Santa Ana, CA) versus in vitro co-oximetry measurements in the intensive care unit (ICU). METHODS: By prospective protocol, we compared blood gas measurements with simultaneously recorded continuous bedside oximetric monitor values for 31 ICU patients with traumatic brain injury undergoing jugular bulb catheter monitoring. For suboptimal fiberoptic light signal quality indices, the catheter was repositioned, flushed, or both before drawing the sample for in vitro measurement. Laboratory and bedside monitor data were examined for association using the X 2 and paired t tests and a linear regression model. RESULTS: We assessed 195 samples (median, 5 per patient; range, 1-14) who were monitored an average of 3.4 (range, 1-6) days. The in vivo monitor (range, 32-94%) and in vitro co-oximetry (range, 38-93%) values had acceptable correlation (y = 0.94x + 4.4, r 2 = 0.80). For bedside monitor detection of jugular bulb desaturation (S j O 2 < 50% for 10 min), the kappa statistic was 0.35, the sensitivity was 45 to 50%, and the specificity was 98 to 100%. CONCLUSION: Continuous ICU S j O 2 monitoring correlates significantly with in vitro values, but less so than previously described during intracranial surgery. Although sensitivity of the bedside monitor to detect confirmed desaturations remains an issue, the high specificity indicates that it is less of a concern that patients may be misdiagnosed as having desaturations resulting in unnecessary interventions. Nonetheless, suspected jugular bulb desaturation should be verified before taking therapeutic actions.

Management of Intrinsic Gliomas of the Tectal Plate in Children

The natural history, management, and long-term outcome for patients with benign, intrinsic tectal plate gliomas remain controversial in spite of their propensity to cause late-onset hydrocephalus. A 10-year retrospective review has identified 11 consecutive children with tectal plate lesions. Headache, vomiting, a decline in school performance, tremor, and complex partial seizures were common presenting symptoms. All patients presented with signs and symptoms of hydrocephalus. Magnetic resonance (MR) imaging delineated an intra-axial mass lesion of the midbrain primarily localized to the tectal plate which uniformly was hyperintense on T2-weighted imaging and had a more variable appearance on T1-weighted imaging and rare enhancement with gadolinium. No patient underwent surgical resection, chemotherapy, or radiotherapy. Three of 11 patients (27%) showed evidence of progression in size or a new focus of enhancement on MR imaging, which was clinically asymptomatic. In this series, no patient with a tectal plate lesion less than 1.5 cm in maximal diameter and without gadolinium enhancement showed any evidence of clinical or radiological progression. Although intrinsic tectal lesions in children are clinically indolent and the initial management consists of CSF diversion, these lesions may eventually progress and still warrant long-term follow-up with serial MR imaging.

Solitary eosinophilic granulomar of the temporal lobe: case report and review of the literature

A solitary eosinophilic granuloma of the central nervous system is an unusual manifestation of histiocytosis X. A unique case of a solitary eosinophilic granuloma of the right temporal lobe without osseous involvement is described. A 20-year-old man presented with a grand mal seizure. Magnetic resonance imaging demonstrated an intraaxial enhancing mass in the right temporal lobe with marked vasogenic edema. A right temporal craniotomy was performed for resection of the lesion and the diagnosis of an eosinophilic granuloma was confirmed by histopathology. Follow-up MR imaging obtained 5 years following resection demonstrated no recurrence. Solitary eosinophilic granuloma should be considered in the differential diagnosis of enhancing mass lesions affecting the central nervous system. Although the natural history of solitary eosinophilic granulomas remains poorly defined, surgical treatment still remains the mainstay of therapy for these unifocal cerebral lesions.

A Large Planum sphenoidale Meningioma with Sinonasal Extension in a Child

Anterior cranial base meningiomas are rare tumors in children. Due to the extensive involvement of orbit, paranasal sinuses, midface, and anterior skull base, a multidisciplinary approach is warranted. We present a case of a child with a large planum sphenoidale meningioma extending into subfrontal region, ethmoid and maxillary sinuses inferiorly, and orbits laterally. The patient, a 4-year-old girl, presented with long-standing nasal stuffiness and swelling of the midface. An extended frontobasal approach through a bifrontal craniotomy was used to resect the intracranial portion of this mass. The tumor had eroded through nasal septum, medial orbital walls, and left maxilla, structures which were not readily accessible from a cranial approach alone. A modified Weber-Ferguson incision was used for a transfacial approach to resect the residual mass below the skull base. The advantages of combining the bifrontal craniotomy with a transfacial split provided the added exposure to maximize the extent of resection.

Peripheral and Cranial Nerve Injury

The peripheral nervous system is an integral component of the neural connection between the CNS and the end organs. Injuries involving this system are often complex and require a thorough understanding of the management strategies of these injuries to help optimize recovery. Recent advances in MRI may lead to its becoming a useful tool in managing peripheral nerve injuries; however, good clinical acumen and the understanding of the anatomy and classification of nerve injuries remain the most important aspects. This chapter will therefore address the anatomy of a peripheral nerve, the classification of nerve injuries and the utility of MRI in diagnoses of peripheral nerve injuries and discuss the evaluation and treatment of injuries to peripheral and cranial nerves.