MR myelography for identification of spinal CSF leak in spontaneous intracranial hypotension

BACKGROUND AND PURPOSE

CT myelography has historically been the test of choice for localization of CSF fistula in patients with spontaneous intracranial hypotension. This study evaluates the additional benefits of intrathecal gadolinium MR myelography in the detection of CSF leak.

MATERIALS AND METHODS

We performed a retrospective review of patients with spontaneous intracranial hypotension who underwent CT myelography followed by intrathecal gadolinium MR myelography. All patients received intrathecal iodine and off-label gadolinium-based contrast followed by immediate CT myelography and subsequent intrathecal gadolinium MR myelography with multiplanar T1 fat-suppressed sequences. CT myelography and intrathecal gadolinium MR myelography images were reviewed by an experienced neuroradiologist to determine the presence of CSF leak. Patient records were reviewed for demographic data and adverse events following the procedure.

RESULTS

Twenty-four patients met both imaging and clinical criteria for spontaneous intracranial hypotension and underwent CT myelography followed by intrathecal gadolinium MR myelography. In 3/24 patients (13%), a CSF leak was demonstrated on both CT myelography and intrathecal gadolinium MR myelography, and in 9/24 patients (38%), a CSF leak was seen on intrathecal gadolinium MR myelography (P = .011). Four of 6 leaks identified independently by intrathecal gadolinium MR myelography related to meningeal diverticula. CT myelography did not identify any leaks independently. There were no reported adverse events.

CONCLUSIONS

Present data demonstrate a higher rate of leak detection with intrathecal gadolinium MR myelography when investigating CSF leaks in our cohort of patients with spontaneous intracranial hypotension. Although intrathecal gadolinium is an FDA off-label use, all patients tolerated the medication without evidence of complications. Our data suggest that intrathecal gadolinium MR myelography is a well-tolerated examination with significant benefit in the evaluation of CSF leak, particularly for patients with leak related to meningeal diverticula.

The Irvine, Beatties, and Bresnahan (IBB) Forelimb Recovery Scale: An Assessment of Reliability and Validity

The IBB scale is a recently developed forelimb scale for the assessment of fine control of the forelimb and digits after cervical spinal cord injury [SCI; (1)]. The present paper describes the assessment of inter-rater reliability and face, concurrent and construct validity of this scale following SCI. It demonstrates that the IBB is a reliable and valid scale that is sensitive to severity of SCI and to recovery over time. In addition, the IBB correlates with other outcome measures and is highly predictive of biological measures of tissue pathology. Multivariate analysis using principal component analysis (PCA) demonstrates that the IBB is highly predictive of the syndromic outcome after SCI (2), and is among the best predictors of bio-behavioral function, based on strong construct validity. Altogether, the data suggest that the IBB, especially in concert with other measures, is a reliable and valid tool for assessing neurological deficits in fine motor control of the distal forelimb, and represents a powerful addition to multivariate outcome batteries aimed at documenting recovery of function after cervical SCI in rats.

Calvarial fracture patterns on CT imaging predict risk of a delayed epidural hematoma following decompressive craniectomy for traumatic brain injury

BACKGROUND AND PURPOSE

The development of a delayed epidural hematoma as a result of decompressive craniectomy represents an urgent and potentially lethal complication in traumatic brain injury. The goal of this study was to determine the incidence of delayed epidural hematoma and whether patterns of skull fractures on the preoperative CT scan could predict risk of a delayed epidural hematoma.

MATERIALS AND METHODS

We retrospectively evaluated medical records and imaging studies for patients with acute traumatic brain injury who underwent a decompressive craniectomy during a 9-year period. We compared patterns of skull fractures contralateral to the side of the craniectomy with the occurrence of a postoperative delayed epidural hematoma.

RESULTS

In a series of 203 patients undergoing decompressive craniectomy for acute traumatic brain injury, the incidence of a delayed epidural hematoma complication was 6% (12 of 203). All 12 patients who developed a delayed epidural hematoma had a contralateral calvarial fracture on preoperative CT at the site where the delayed epidural hematoma subsequently formed. A contralateral calvarial fracture has perfect sensitivity (100%) for subsequent development of delayed epidural hematoma in our study population. Moreover, a contralateral calvarial fracture involving 2 or more bone plates had an especially high diagnostic odds ratio of 41 for delayed epidural hematoma.

CONCLUSIONS

Recognition of skull fracture patterns associated with delayed epidural hematoma following decompressive craniectomy may reduce morbidity and mortality by prompting early postoperative intervention in high-risk situations.

CNTF promotes the survival and differentiation of adult spinal cord-derived oligodendrocyte precursor cells in vitro but fails to promote remyelination in vivo

Delivery of factors capable of promoting oligodendrocyte precursor cell (OPC) survival and differentiation in vivo is an important therapeutic strategy for a variety of pathologies in which demyelination is a component, including multiple sclerosis and spinal cord injury. Ciliary neurotrophic factor (CNTF) is a neuropoietic cytokine that promotes both survival and maturation of a variety of neuronal and glial cell populations, including oligodendrocytes. Present results suggest that, although CNTF has a potent survival and differentiation promoting effect in vitro on OPCs isolated from the adult spinal cord, CNTF administration in vivo is not sufficient to promote oligodendrocyte remyelination in the glial-depleted environment of unilateral ethidium bromide (EB) lesions.

Schwann cell-like differentiation by adult oligodendrocyte precursor cells following engraftment into the demyelinated spinal cord is BMP-dependent

The development of remyelinating strategies designed to enhance recruitment and differentiation of endogenous precursor cells available to a site of demyelination in the adult spinal cord will require a fundamental understanding of the potential for adult spinal cord precursor cells to remyelinate as well as an insight into epigenetic cues that regulate their mobilization and differentiation. The ability of embryonic and postnatal neural precursor cell transplants to remyelinate the adult central nervous system is well documented, while no transplantation studies to date have examined the remyelinating potential of adult spinal-cord-derived oligodendrocyte precursor cells (adult OPCs). In the present study, we demonstrate that, when transplanted subacutely into spinal ethidium bromide/X-irradiated (EB-X) lesions, adult OPCs display a limited capacity for oligodendrocyte remyelination. Interestingly, the glia-free environment of EB lesions promotes engrafted adult OPCs to differentiate primarily into cells with immunophenotypic and ultrastructural characteristics of myelinating Schwann cells (SCs). Astrocytes modulate this potential, as evidenced by the demonstration that SC-like differentiation is blocked when adult OPCs are co-transplanted with astrocytes. We further show that inhibition of bone morphogenetic protein (BMP) signaling through noggin overexpression by engrafted adult OPCs is sufficient to block SC-like differentiation within EB-X lesions. Present data suggest that the macroglial-free environment of acute EB lesions in the ventrolateral funiculus is inhibitory to adult spinal cord-derived OPC differentiation into remyelinating oligodendrocytes, while the presence of BMPs and absence of noggin promotes SC-like differentiation, thereby unmasking a surprising lineage fate for these cells.

Functional considerations of stem cell transplantation therapy for spinal cord repair

Stem cells hold great promise for therapeutic repair after spinal cord injury (SCI). This review compares the current experimental approaches taken towards a stem cell-based therapy for SCI. It critically evaluates stem cell sources, injury paradigms, and functional measurements applied to detect behavioral changes after transplantation into the spinal cord. Many of the documented improvements do not exclusively depend on lineage-specific cellular differentiation. In most of the studies, the functional tests used cannot unequivocally demonstrate how differentiation of the transplanted cells contributes to the observed effects. Standardized cell isolation and transplantation protocols could facilitate the assessment of the true contribution of various experimental parameters on recovery. We conclude that at present embryonic stem (ES)-derived cells hold the most promise for therapeutic utility, but that non-neural cells may ultimately be optimal if the mechanism of possible transdifferentiation can be elucidated.

Endogenous Nkx2.2+/Olig2+ oligodendrocyte precursor cells fail to remyelinate the demyelinated adult rat spinal cord in the absence of astrocytes

Chronic demyelination is a pathophysiologic component of compressive spinal cord injury (SCI) and a characteristic finding in demyelinating diseases including multiple sclerosis (MS). A better characterization of endogenous cells responsible for successful remyelination is essential for designing therapeutic strategies aimed at restoring functional myelin. The present study examined the spatiotemporal response of endogenous oligodendrocyte precursor cells (OPCs) following ethidium bromide (EB)-induced demyelination of the adult rat spinal cord. Beginning at 2 days post-EB injection (dpi), a robust mobilization of highly proliferative NG2(+) cells within the lesion was observed, none of which expressed the oligodendrocyte lineage-associated transcription factor Nkx2.2. At 7 dpi, a significant up-regulation of Nkx2.2 by OPCs within the lesion was observed, 90% of which coexpressed NG2 and virtually all of which coexpressed the bHLH transcription factor Olig2. Despite successful recruitment of Nkx2.2(+)/Olig2(+) OPCs within the lesion, demyelinated axons were not remyelinated by these OPCs in regions lacking astrocytes. Rather, Schwann cell remyelination predominated throughout the central core of the lesion, particularly around blood vessels. Oligodendrocyte remyelination was observed in the astrogliotic perimeter, suggesting a necessary role for astrocytes in oligodendrocyte maturation. In addition, reexpression of the radial glial antigen, RC-1, by reactive astrocytes and ependymal cells was observed following injury. However, these cells did not express the neural stem cell (NSC)-associated transcription factors Sox1 or Sox2, suggesting that the endogenous response is primarily mediated by glial progenitors. In vivo electrophysiology demonstrated a limited and unsustained functional recovery concurrent with endogenous remyelination following EB-induced lesions.

Serum Biomarkers for Experimental Acute Spinal Cord Injury: Rapid Elevation of Neuron-specific Enolase and S-100β

OBJECTIVE

We evaluated whether serum levels of neuron-specific enolase (NSE) and S-100beta protein are biomarkers for traumatic injury in an animal model of spinal cord injury (SCI).

METHODS

Enzyme-linked immunosorbent assay serum measurements of NSE and S-100beta and assays of serum protein were compared at 6 and 24 hours after a graded contusive SCI (150 or 200 kdyn IH impactor injury (Infinite Horizons, L.L.C., Lexington, KY) or sham laminectomy at T9 in 30 female Sprague-Dawley rats. Serum from control animals was also analyzed.

RESULTS

Increases in serum levels of NSE were observed for 200-kdyn (3.1-fold, P < 0.001) and 150-kdyn (2.3-fold, P < 0.001) injury groups at 6 hours after injury, which decreased by 73.7% (P < 0.001) and 65.2% (P < 0.001) at 24 hours after SCI, respectively; the levels were still greater than in sham animals (P < 0.001, P = 0.001). The 200- and 150-kdyn injury groups were not different at either time point. S-100beta serum levels increased at 6 hours in the 200-kdyn injury group (P < 0.05), and no differences from sham levels were seen at 24 hours. No differences in total protein concentrations were observed between the injury and control groups.

CONCLUSION

Present data suggest that NSE and S-100beta serum levels may be useful experimental tools for the acute measurement of tissue loss after SCI. Despite significant shortcomings, NSE and S-100beta serum measurements in acute SCI patients with clinically defined functional deficits should allow comparisons with well-characterized SCI animal models. Future efforts to develop biomarkers that predict functional outcomes in the acute phase should focus on axon-specific proteins as markers of secondary axonal loss and regeneration.

Acid and base secretion in the Calu-3 model of human serous cells

Submucosal glands are the primary source of airway mucus, a critical component of lung innate defenses. Airway glands are defective in cystic fibrosis (CF), showing a complete absence of secretion to vasoactive intestinal peptide or forskolin, which increase intracellular cAMP concentration. This defect is attributed to gland serous cells, which express the cystic fibrosis transmembrane conductance regulator. Calu-3 cells, which mimic many features of serous cells, secrete Cl(-) and HCO(3)(-), with HCO(3)(-) secretion predominating for forskolin stimulation and Cl(-) secretion predominating for stimuli that open basolateral K(+) channels to hyperpolarize the cells. We used pH stat and ion substitution experiments to clarify the mechanisms and consequences of these two modes of secretion. We confirm that Calu-3 cells secrete primarily HCO(3)(-) in response to forskolin. Unexpectedly, HCO(3)(-) secretion continued in response to K(+) channel openers, with Cl(-) secretion being added to it. Secretion of HCO(3)(-) from hyperpolarized cells occurs via the conversion of CO(2) to HCO(3)(-) and is reduced by approximately 50% with acetazolamide. A gap between the base equivalent current and short-circuit current was observed in all experiments and was traced to secretion of H(+) via a ouabain-sensitive, K(+)-dependent process (possibly H(+)-K(+)-ATPase), which partially neutralized the secreted HCO(3)(-). The conjoint secretion of HCO(3)(-) and H(+) may help explain the puzzling finding that mucus secreted from normal and CF glands has the same acidic pH as does mucus from glands stimulated with forskolin or ACh. It may also help explain how human airway glands produce mucus that is hypotonic.

Both dorsal and ventral spinal cord pathways contribute to overground locomotion in the adult rat

Identification of long tracts responsible for spontaneous locomotion is critical for spinal cord injury (SCI) repair strategies. We recently demonstrated that extensive demyelination of adult rat thoracic ventral columns, ventromedial, and ventrolateral white matter produces persistent, significant open-field hindlimb locomotor deficits. Locomotor movements resulting from stimulation of the pontomedullary locomotor region are inhibited by dorsolateral funiculus (DLF) lesions suggesting that important pathways for locomotion may also exist in the dorsal white matter. However, dorsal hemisections that interrupt dorsal columns/dorsal corticospinal tract (DC/CST) and DLF pathways do not produce persistent, severe locomotor deficits in the adult rat. We studied the contributions of myelinated tracts in the DLF and DC/CST to overground locomotion following complete conduction blockade of axons in the ventrolateral funiculus (VLF), a region important for locomotor movements and for transcranial magnetic motor-evoked potentials (tcMMEP). Animals received ethidium bromide plus photon irradiation to produce discrete demyelinating lesions sufficient to stop axonal conduction in the VLF, combined VLF + DLF, or combined VLF + DC/CST. Open-field BBB scores and tcMMEPs were studied at 1, 2, 3, and 4 weeks postlesion. VLF lesions resulted in mean BBB scores of 17 at 4 weeks. VLF + DC/CST and VLF + DLF lesions resulted in mean BBB scores of 15.9 and 11.1, respectively. TcMMEPs were absent in all lesion types confirming VLF conduction blockade throughout the study. Our data indicate that significant contributions to locomotion from myelinated pathways within the rat DLF can be revealed when combined with simultaneous compromise of the VLF.

Midfacial osteomyelitis in a chronic cocaine abuser: a case report

We describe the case of a 56-year-old man who was admitted for treatment of a progressive destruction of his hard palate, septum, nasal cartilage, and soft palate that had been caused by chronic cocaine inhalation. Biopsy of the bony septum revealed acute osteomyelitis and an extensive overgrowth of bacteria and Actinomyces-like organisms. There was no evidence of granuloma or neoplasm. The patient received intravenous ampicillin/sulbactam for 6 weeks, followed by lifetime oral amoxicillin. When there was no further evidence that destruction was progressing, the patient underwent nasal reconstruction with a cranial bone graft. The surgery was completed with no complications. To our knowledge, this is the first reported case of midfacial osteomyelitis associated with chronic cocaine abuse. The severity of this patient's complications, coupled with the success of his reconstructive surgery, makes this case particularly interesting. We believe that it is important for physicians to understand that septal perforation in a cocaine abuser should not be underestimated because it could result in a secondary bone infection. Nasoseptal destruction secondary to intranasal cocaine abuse is a result of cocaine's vasoconstrictive properties, and a decrease in the oxygen tension of intranasal tissue can facilitate the growth of anaerobic pathogens.

Midfacial Osteomyelitis in a Chronic Cocaine Abuser: A Case Report

We describe the case of a 56-year-old man who was admitted for treatment of a progressive destruction of his hard palate, septum, nasal cartilage, and soft palate that had been caused by chronic cocaine inhalation. Biopsy of the bony septum revealed acute osteomyelitis and an extensive overgrowth of bacteria and Actinomyces- like organisms. There was no evidence of granuloma or neoplasm. The patient received intravenous ampicillin/sulbactam for 6 weeks, followed by lifetime oral amoxicillin. When there was no further evidence that destruction was progressing, the patient underwent nasal reconstruction with a cranial bone graft. The surgery was completed with no complications. To our knowledge, this is the first reported case of midfacial osteomyelitis associated with chronic cocaine abuse. The severity of this patient's complications, coupled with the success of his reconstructive surgery, makes this case particularly interesting. We believe that it is important for physicians to understand that septal perforation in a cocaine abuser should not be underestimated because it could result in a secondary bone infection. Nasoseptal destruction secondary to intranasal cocaine abuse is a result of cocaine's vasoconstrictive properties, and a decrease in the oxygen tension of intranasal tissue can facilitate the growth of anaerobic pathogens.