Prospective analysis of single operator sonographic optic nerve sheath diameter measurement for diagnosis of elevated intracranial pressure.

INTRODUCTION: The accurate diagnosis of elevated intracranial pressure (eICP) in the emergent setting is a critical determination that presents significant challenges. Several studies show correlation of sonographic optic nerve sheath diameter (ONSD) to eICP, while others show high inter-observer variability or marginal performance with less experienced sonographers. The objective of our study is to assess the ability of bedside ultrasound measurement of ONSD to identify the presence of eICP when performed by a single experienced sonographer. We hypothesize that ONSD measurement is sensitive and specific for detecting eICP and can be correlated with values obtained by external ventricular device (EVD). METHODS: This was a prospective blinded observational study conducted in a neurocritical care unit of a level 1 trauma center. ONSD measurement was performed on a convenience sample of 27 adult patients who required placement of an invasive intracranial monitor as part of their clinical care. One certified sonographer/physician performed all ultrasounds within 24 hours of placement of EVD. The sonographer was blinded to the ICP recorded by invasive monitor at the time of the scan. A mean ONSD value of ≥5.2 mm was taken as positive. RESULTS: The sonographer performed 27 ocular ultrasounds on individual patients. Six (22%) of these patients had eICP (EVD measurement of >20 mmHg). Spearman rank correlation coefficient of ONSD and ICP was 0.408 (p=0.03), demonstrating a moderate positive correlation. A ROC curve was created to determine the optimal cut off value to distinguish an eICP greater than 20 mmHg. The area under the receiver operator characteristic curve was 0.8712 (95% confidence interval [CI]=0.67 to 0.96). ONSD ≥5.2 mm was a good predictor of eICP (>20 mmHg) with a sensitivity of 83.3% (95% CI=35.9% to 99.6%) and specificity of 100% (95% CI=84.6% to 100%). CONCLUSION: While the study suggests ONSD measurements performed by a single skilled operator may be both sensitive and specific for detecting eICP, confirmation in a much larger sample is needed. Ocular ultrasound may provide additional non-invasive means of assessing eICP.

Toxic leukoencephalopathy with atypical MRI features following a lacquer thinner fire.

Toxic leukoencephalopathy is a structural alteration of the white matter following exposure to various toxic agents. We report a 49-year-old man exposed to an explosion of lacquer thinner with brain MRI features atypical from those of chronic toxic solvent intoxication.

Vertebral artery anomaly causing C2 suboccipital neuralgia, relieved by neurovascular decompression.

We report imaging and surgical findings of a symptomatic 40-year-old male with an anomalous left vertebral artery. MR, CT myelography, angiography, and intraoperative photos demonstrate the vertebral artery entering the thecal sac at the C1-C2 intervertebral foramen and compressing the dorsal C2 nerve rootlets against the cord. Open microvascular decompression alleviated the patient's long-standing suboccipital and posterior cervical neck pain. An embryologic review of the vertebral and lateral spinal artery systems reveals possible developmental explanations for this variant. Intradural course of the vertebral artery at C2 is one of the few symptomatic developmental vertebral artery anomalies. Recognition of this condition is important because surgical intervention can alleviate associated neck pain.

Retroperitoneal transdiaphragmatic robotic-assisted laparoscopic resection of a left thoracolumbar neurofibroma.

OBJECTIVE: Robotic technology has been used in a variety of surgical procedures for its 3D magnification and precision. Minimally invasive techniques have already become common in neurosurgery; however, robotic-assisted procedures in neurosurgery are still a relatively new frontier. This report describes the first use of robotic technology to resect a left thoracolumbar neurofibroma. CASE REPORT: A 19-year-old male with a family history of neurofibromatosis was diagnosed with a suspected 3-cm x 4-cm neurofibroma in the T12-L1 left paraspinal area. His only complaint was back pain requiring narcotic analgesics. He had no other findings on physical examination or laboratory/radiologic workup. METHODS: After consulting urologic robotic surgeons, it was agreed to use the da Vinci robot (Intuitive Surgical, Sunnyvale, CA) for the resection of this mass. Following retroperitoneal laparoscopic access, the urologic surgeons opened the diaphragm and began the initial mobilization of the mass laparoscopically. The robot was docked, and the neurosurgeon operated the robot at the console to resect the mass from its nerve origin. There were no complications, and the mass, a confirmed neurofibroma, was completely removed. The patient was discharged on postoperative day 2; his back pain resolved, requiring no analgesia by the end of the first postoperative week. CONCLUSION: This case provides early evidence that robotic assistance can be successfully used for the resection of a paraspinal neurofibroma.

Primary leptomeningeal oligodendrogliomatosis.

Primary leptomeningeal oligodendrogliomas (PLOs) are rare intracranial malignancies where tumors grow in the subarachnoid space without an obvious connection to the brain or spinal cord parenchyma. Adding to the three previously reported cases of PLO with no parenchymal involvement we report a fourth case of the same in this paper in a 50-year-old woman presenting with unrelenting headaches. CT scan of her head revealed hydrocephalus and MRI revealed diffuse enhancement of her leptomeninges throughout her brain and spine, prominent over the basilar region. Biopsy obtained using a frameless stereotactic biopsy showed sharply defined cell borders, clear cytoplasm, and rounded nuclei consistent with an oligodendroglioma. Our case suggests that PLO can mimic diffuse forms of granulomatous meningitis and should be suspected in patients that clinically and radiographically present like granulomatous meningitis but without blood or CSF markers for the same.

GORE PRECLUDE MVP dura substitute applied as a nonwatertight "underlay" graft for craniotomies: product and technique evaluation.

BACKGROUND: While watertight closure of the dura is a long-standing tenet of cranial surgery, it is often not possible and sometimes unnecessary. Many graft materials with various attributes and drawbacks have been in use for many years. A novel synthetic dural graft material called GORE PRECLUDE MVP dura substitute (WL Gore & Associates, Inc, Flagstaff, Ariz) (henceforth called "MVP") is designed for use both in traditional watertight dural closure and as a dural "underlay" graft in a nonwatertight fashion. One surface of MVP is engineered to facilitate fibroblast in-growth so that its proximity to the underside of the dura will lead to rapid incorporation, whereas the other surface acts as a barrier to reduce tissue adhesion to the device. METHODS: A series of 59 human subjects undergoing craniotomy and available for clinical and radiographic follow-up underwent nonwatertight underlay grafting of their durotomy with MVP. This is an assessment of the specific product and technique. No attempt is made to compare this to other products or techniques. RESULTS: The mean follow-up in this group was more than 4 months. All subjects have ultimately experienced excellent outcomes related to use of the graft implanted with the underlay technique. No complications occurred related directly to MVP, but the wound-related complication rate attributed to the underlay technique was higher than expected (17%). However, careful analysis found a high rate of risk factors for wound complications and determined that complications with the underlay technique could be avoided by assuring close approximation of the graft material to the underside of the dura. CONCLUSIONS: MVP can be used as an underlay graft in a nonwatertight fashion. However, if used over large voids (relaxed brain or large tumor bed), "tacking" or traditional watertight closure techniques should be used. The underlay application of MVP is best applied over the convexities and is particularly well-suited to duraplasty after hemicraniectomy.

Spinal angiolipoma: case report and literature review.

BACKGROUND/OBJECTIVE: Spinal angiolipoma (SAL) is an uncommon clinico-pathological entity. DESIGN: Single case report. METHODS: Retrospective data analysis. FINDINGS: An obese woman with a 1-year history of progressive spastic paraparesis and acute deterioration underwent magnetic resonance imaging of the thoracic spine, the results of which suggested a tumor compressing the thoracic spinal cord. The histopathological examination of the completely resected tumor revealed an epidural angiolipoma. CONCLUSIONS: This case report offers a reminder that SAL should be considered in the differential diagnosis of long-standing, slowly progressive paraparesis. It remains unclear whether an increased body mass index might be a contributing factor to the development of SAL.

Slope of the intracranial pressure waveform after traumatic brain injury.

BACKGROUND: The measurement and treatment of ICP within the management of TBI generally focuses on keeping the mean ICP to less than 20 mm Hg. More sophisticated analysis of the intracranial pressure waveform has yielded important relationships, but those methods have not gained widespread use. Prior analysis of the slope of the ICP waveform during inspiration and expiration in patients with hydrocephalus has provided valuable information that has never been applied to patients with TBI. This study used digital methods to examine ICP and the slope of the ICP waveform in relation to the respiratory cycle in subjects with TBI. METHODS: Intracranial pressure was monitored in 6 randomly selected patients admitted with acute TBI. In the first 3 subjects, a single 5-minute recording was analyzed. In 3 subsequent subjects, 4 nonsequential 5-minute epochs were analyzed during periods of varying ICP. The systolic slope of the ICP waveform was compared during inspiration and expiration, and then evaluated in relation to simultaneous mean ICP. RESULTS: The slope of the systolic ICP waveform was significantly greater during inspiration than during expiration (P < .0001 for 5 subjects and P < .03 for 1 subject). Within each subject, the ICP slope was positively correlated with simultaneous ICP (P < .0001 in all 6 cases). CONCLUSION: Greater systolic ICP waveform slope during inspiration has not been described previously after TBI and is consistent with prior observations in subjects with hydrocephalus. The strong correlation between ICP slope and simultaneous mean ICP suggests that increasing ICP slope might indicate loss of intracranial compliance after TBI.

Recognizing schwannomatosis and distinguishing it from neurofibromatosis type 1 or 2.

BACKGROUND DATA: Schwannomatosis has become a newly recognized classification of neurofibromatosis. Although the genetic loci are on chromosome 22, it lacks the classic bilateral vestibular schwannomas as seen in NF-2. We present the surgical treatment of 4 patients with schwannomatosis, including a brother and sister. METHOD: Case 1 presented with multiple progressively enlarging peripheral nerve sheath tumors. Case 4 presented with a trigeminal schwannoma and a vagal nerve schwannoma. Three of 4 patients had spinal intradural, extramedullary nerve sheath tumors. Surgery in all was multistaged and consisted of spinal laminectomies, site-specific explorations, and microsurgical tumor dissection and resection, with intraoperative neurophysiologic monitoring (including somatosensory-evoked and motor-evoked potentials, upper extremity electromyography and intraoperative nerve action potential monitoring, as appropriate). RESULTS: Intraoperatively the schwannomas had cystic and solid features and in all surgical cases the tumors arose from discrete fascicles of sensory nerve roots or sensory peripheral nerve branches. None of the patients experienced neurologic worsening as a result of their resections. Pathologic analysis of specimens from all cases demonstrated schwannoma. CONCLUSIONS: Not all patients with multiple schwannomas of cranial nerve, spinal nerve root, or peripheral nerve origin have NF-1 or NF-2. In schwannomatosis, these lesions are present in the absence of cutaneous stigmata, neurofibromas, vestibular schwannomas, or parenchymal brain tumors. Schwannomas in schwannomatosis can be large, cystic, and multiple. However, the predominant nerve involvement seems to be sensory and discrete fascicular in origin, facilitating microsurgical resection with minimal deficit.

Intraventricular cryptococcal cysts masquerading as racemose neurocysticercosis.

BACKGROUND: Cryptococcal infections of the CNS are infrequent in immunocompetent hosts. When present, they usually present as meningitis and hydrocephalus or as fungal masses called cryptococcomas. We report a case in which intraventricular cryptococcal cysts clinically and radiologically simulated the racemose form of neurocysticercosis. CASE DESCRIPTION: A 23-year-old man presented to the emergency department with a 1-week history of severe headache, dizziness, nausea, vomiting, and some lethargy. A computed tomography scan revealed significant hydrocephalus. The patient was admitted to the hospital and immediately underwent a right ventriculostomy tube placement. CSF examination showed a meningitic pattern. Magnetic resonance imaging, including FLAIR images, showed multiple large cysts in the temporal horns of both lateral ventricles in addition to hydrocephalus. When an endoscopic left temporal cyst fenestration failed to decompress his trapped right temporal horn, he underwent placement of a left lateral ventricle to peritoneal shunt and a right temporal cyst to peritoneal shunt. ELISA test results for HIV-1 and -2 antibodies in the patient's serum were negative. His CD4 and CD8 counts were within normal limits. Multiple tests for CSF anticysticercal antibody using IgG ELISA gave unequivocally negative results. Latex agglutination tests detected Cryptococcus neoformans antigen in his CSF in titers of 1:1024, which progressively decreased in response to antifungal therapy. The patient underwent treatment with IV amphotericin B for 7 weeks, IV 5-FC for 2 weeks, and oral fluconazole for 5 weeks. At discharge, 3 consecutive CSF cultures were negative for bacteria and fungi. His neurologic status returned to baseline. CONCLUSIONS: Cryptococcal CNS infections in immunocompetent hosts can mimic the intraventricular form of racemose neurocysticercosis. Distinguishing between the two is essential because the medical management of the 2 conditions is distinct from each other.

Central causes of foot drop: rare and underappreciated differential diagnoses.

BACKGROUND/OBJECTIVE: Peripheral causes of foot drop are well recognized. However, causes stemming from the central nervous system represent rare, important, and underappreciated differential etiologies. METHODS: Two cases of foot drop stemming from central causes are described. PATIENTS: The first patient, a 46-year-old man with a remote history of lumbar spine fracture and L4-L5 instrumentation/fusion, presented with progressive weakness and numbness of the left foot, followed within 3 months by similar symptoms in the right foot. Lumbar spine imaging failed to reveal compressive nerve root pathology. Electromyography, nerve conduction studies, and muscle and nerve biopsy suggested a preganglionic lesion and ruled out a peripheral cause. Upper spine magnetic resonance imaging (MRI) revealed significant spinal stenosis at C4-C7 and T11-T12. Patient 2 was a 66-year-old man with a known left parasagittal convex meningioma diagnosed 2 years prior presented with a progressive right foot drop over 2 months. Spine imaging was normal, and serial brain MRI confirmed a slowly enlarging parasagittal meningioma. RESULTS: Following decompressive laminectomies at C4-C7 and T11-T12, patient 1's gait improved, with marked resolution of his right foot drop and significant improvement on the left. Patient 2 underwent craniotomy for microsurgical tumor resection. At the 2-week follow-up examination, he was taking daily walks. CONCLUSIONS: Central causes, although rare, need to be considered in the differential diagnosis of foot drop. Central causative lesions usually occur at locations where pyramidal tract connections are condensed and specific and the function is somatotopically organized. These cases confirm that good results can be achieved when correctable central causes of foot drop are recognized.

Frameless stereotaxy to facilitate anterolateral thoracolumbar surgery: technique.

With the advent of frameless stereotaxy and its application to the spine, more precise and less invasive spinal procedures are possible. In addition to being less invasive, these techniques may increase surgeon confidence and allow shorter operating times. Described here is a case of Pott's disease of the thoracolumbar spine and how intraoperative image guidance can facilitate operative progress and accuracy in a patient in whom the underlying disease has severely deformed the normal anatomy of the spine. Added confidence about the location of vital structures as the surgeon proceeds with resection of the vertebral bodies and discs is depicted. Facilitation with image-guided placement of bicortical vertebral body screws and an interbody device is demonstrated. A diagram of the recommended positioning of the equipment in the operating room is provided along with "pearls" learned from our experience with this application. We believe that even the most experienced and skilled surgeon will find facilitation of anterior thoracolumbar surgery with image guidance to be of considerable benefit.