Abhineet Chowdhary

Time-Dependent Alterations in Functional and Pharmacological Arteriolar Reactivity After Subarachnoid Hemorrhage

Background and Purpose— Disturbances in cerebral arteriolar function, in addition to large vessel vasospasm, may be responsible for ischemia after subarachnoid hemorrhage. The purpose of this study was to test the hypothesis that subarachnoid hemorrhage alters cerebral microvascular reactivity. Methods— An endovascular filament model was used to induce subarachnoid hemorrhage in halothane-anesthetized male Sprague-Dawley rats. We evaluated pial arteriolar responses to sciatic nerve stimulation, topically applied vasoactive agents (adenosine or sodium nitroprusside), and CO2 inhalation in rats subjected to subarachnoid hemorrhage at 1 to 5 days after insult. Results— In sham-operated rats, sciatic nerve stimulation evoked a 23.5±1.8% increase in arteriolar diameter, which was significantly attenuated to 13.7±0.9%, 12.8±2.5%, and 18.8±2.9% at 24, 48, and 72 hours after subarachnoid hemorrhage, respectively (P<0.05; n≥7). At 96 and 120 hours after subarachnoid hemorrhage, sciatic nerve stimulation-induced dilation recovered to sham levels. Somatosensory-evoked potentials were unaltered by subarachnoid hemorrhage. Pial vasodilatation to adenosine (10 &mgr;mol/L) and sodium nitroprusside (1 &mgr;mol/L) were significantly impaired, by 47% and 41%, respectively, at 48 hours after subarachnoid hemorrhage (P<0.05; n=7). In contrast, CO2 reactivity was unaffected by subarachnoid hemorrhage. Conclusions— Pial arteriolar responses to cortical activation may be decreased in the initial 2 to 3 days after experimental subarachnoid hemorrhage.

Impairment of intracerebral arteriole dilation responses after subarachnoid hemorrhage: Laboratory investigation

OBJECT Cerebrovascular dysfunction after subarachnoid hemorrhage (SAH) may contribute to ischemia, but little is known about the contribution of intracerebral arterioles. In this study, the authors tested the hypothesis that SAH inhibits the vascular reactivity of intracerebral arterioles and documented the time course of this dysfunction. METHODS Subarachnoid hemorrhage was induced using an endovascular filament model in halothane-anesthetized male Sprague-Dawley rats. Penetrating intracerebral arterioles were harvested 2, 4, 7, or 14 days postinsult, cannulated using a micropipette system that allowed luminal perfusion and control of luminal pressure, and evaluated for reactivity to vasodilator agents. RESULTS Spontaneous tone developed in all pressurized (60 mm Hg) intracerebral arterioles harvested in this study (from 66 rats), with similar results in the sham and SAH groups. Subarachnoid hemorrhage did not affect dilation responses to acidic pH (6.8) but led to a persistent impairment of endothelium-dependent dilation responses to adenosine triphosphate (p < 0.01), as well as a transient attenuation (p < 0.05) of vascular smooth muscle-dependent dilation responses to adenosine, sodium nitroprusside, and 8-Br-cyclic guanosine monophosphate (cGMP). Impairment of NO-mediated dilation was more sustained than adenosine- and 8-Br-cGMP-induced responses (up to 7 days postinsult compared with 2 days). All smooth muscle-dependent responses returned to sham levels by 14 days after SAH. CONCLUSIONS Subarachnoid hemorrhage led to a persistent impairment of endothelium-dependent dilation and a transient attenuation of vascular smooth muscle-dependent dilation responses to adenosine. Impairment of NO-mediated dilation occurred when the response to cGMP was intact, suggesting a change in cGMP levels rather than an alteration in intracellular mechanisms downstream from cGMP.

Ventriculoperitoneal shunt malfunction presenting as acute paraparesis in an infant

402 J Neurosurg: Pediatrics / Volume 5 / April 2010 Ventriculoperitoneal (VP) shunt surgery is a common treatment for congenital hydrocephalus. Patients with VP shunt malfunctions typically present with headache, nausea, vomiting, increased head circumference, or altered mental status. Syringomyelia with concomitant paraparesis has been reported as a complication of VP shunt malfunction1–3 but only in the setting of Chiari Type II malformation.4 This 23-month-old girl, with surgical history of myelomeningocele repair on her 1st day of life and VP shunt placement, presented to the emergency department with inability to ambulate. Her mother stated she was able to walk without difficulty until a few days prior to presentation when the child expressed reluctance to bear weight on her lower limbs. The mother specifically denied signs of nausea and vomiting, drowsiness, or headache. Neurological examination at this time was notable for lower-extremity hyperreflexia with clonus and an inability to move both lower limbs spontaneously. Otherwise her neurological status was normal. Head CT scanning revealed ventricular enlargement (Fig. 1A) compared with a previous study (Fig. 1B). Spinal MR imaging revealed a holocord syrinx (Fig. 1C). The patient was taken to the operating room for shunt revision, where her shunt tubing was found to be obstructed proximally. A third ventriculostomy was not considered because the patient had communicating hydrocephalus. In the recovery room following surgery, the patient was able to move her legs spontaneously, without hyperreflexia, and the next day she could ambulate regularly. Six weeks after revision surgery, spinal MR imaging revealed significant reduction in the holocord syrinx (Fig. 1D). This case illustrates that syringomyelia should be included in the differential diagnosis of previously shunt-treated patients presenting with acute paraparesis. Prompt shunt revision is indicated and can result in excellent clinical outcome for these patients. (DOI: 10.3171/2009.10.PEDS09191)

Paradoxical Emboli Secondary to Hepatic Pathology: Common or Coincidental?

Paradoxical cerebral emboli from cardiac and pulmonary sources are well described in the peer-reviewed literature. We outline a case with a hepatic etiology and describe diagnostic and management options. Though this paper represents the first documentation of such, we believe that transpulmonary shunting with concurrent paradoxical cerebral microemboli is more prevalent than recognized. We introduce this case report to compel practitioners to consider paradoxical emboli in selected cirrhotic patients since it can often be difficult to elicit subtle neurologic changes on clinical examination of patients with end stage liver disease.

Resolution of Acute Hydrocephalus and Migration of Neurocysticercosis Cyst with External Ventricular Drainage

Neurocysticercosis is endemic in the developing world, but is becoming more common in the US due to immigration. A 24-year-old man presented with acute hydrocephalus and headaches, nausea, and vomiting. Head CT revealed a 3rd ventricular cyst and immunological studies were suggestive of neurocysticercosis. EVD placement resulted in migration of the cyst interiorly and superiorly with return of normal CSF flow by MRI and resolution of symptoms. Review of this condition is important given increasing incidence in the United States.

Ectopic glioneuronal tissue in the middle cranial fossa region

The growth of ectopic glioneuronal tissue in the middle cranial fossa region is an uncommon event, with very few cases reported in the literature. In this paper the authors document 4 cases of ectopic glioneuronal tissue in the middle cranial fossa in children and briefly describe the clinical course and pathology. All of the children presented within the first 6 months of life. Two children presented with facial masses, 1 with airway obstruction, and another with proptosis of the right eye. Each child underwent a customized surgery dependent on the location and characteristics of the harbored lesion. Ectopic glioneuronal masses in the middle cranial fossa are rare and benign congenital tumors, and affected newborns can present with airway obstruction, feeding difficulties, and facial deformity depending on the lesion location. Determining an appropriate surgical approach and strategy is a significant challenge and may involve a multidisciplinary team of craniofacial plastic surgeons, otolaryngologists, and neurosurgeons. Although these lesions share clinical and anatomical similarities, because of their histopathological heterogeneity, it is unlikely that they represent a single pathological entity. The long-term outcome in these children is still unknown and is an area for future study. The pathogenesis of these lesions also remains unknown and may be revealed in future research.

THORACIC SPINAL CORD COMPRESSION BY INTRAMEDULLARY HAMARTOMATOUS TISSUE IN A YOUNG BOY : CASE REPORT

OBJECTIVESpinal cord hamartomas are a rare occurrence characterized by well- differentiated mature elements located in an irregular position in the spinal cord. CLINICAL PRESENTATIONThe authors present the unique case of a 12-year-old boy who originally presented to our center for treatment of a right thalamic astrocytoma. One year after his initial presentation, the child developed progressive bilateral leg weakness with decreased sensation. Spinal magnetic resonance imaging performed at this time revealed an intramedullary spinal cord lesion from T4 to T8, which was later found to be composed of hamartomatous tissue. INTERVENTIONThe patient underwent bilateral T4 to T8 laminectomies with subtotal resection of the hamartomatous lesion, and his symptoms improved postoperatively. CONCLUSIONAlthough typically described in the literature as spinal cord hamartomas because of their histological composition, these rare hamartomatous lesions may be the result of a neurulation defect rather than true hamartomas. In patients presenting with multiple neurological conditions, as in our case, diagnosis may be more complex. For those presenting with neurological signs and symptoms, surgical treatment is essential.

Isolated Superior Orbital Fissure Syndrome Resulting From Gunshot Wound to the Head

A 41-year-old man, shot in the face with a handgun, showed left V1 paraesthesia, limited light perception in the left eye, and complete ophthalmoplegia with proptosis and mydriasis. Unenhanced computed tomography (CT) scan showed multiple comminuted fractures of the left orbit, with the bullet lodged near the superior orbital fissure (Fig 1A). Cranial CT angiogram (Fig 1B) and cerebral angiogram (Fig 2) showed dilation of the left superior orbital vein and an isolated segmental 50% narrowing of the internal carotid artery without intrinsic abnormality. Surgical exploration was declined. Despite treatment with high-dose steroids, severe ophthalmoplegia remained, although vision rapidly improved. The complexity of the orbital apex is related to the confluence of crucial neurovascular structures as they transition from the cranium to the orbit and face. The ophthalmic artery and cranial nerves (CN) II, III, IV, V1, and VI transition from the middle cranial fossa to the orbital apex via the superior orbital fissure. Medially, the superior orbital fissure is enclosed by the annulus of Zinn, from which the 4 extraocular recti muscles arise. The infraorbital artery and vein and CN V2 transition via the infraorbital foramen. Superior orbital fissure syndrome (SOFS) reflects injury to neurovascular structures traversing the superior orbital fissure manifest by fixed and dilated pupil (parasympathetic branches of CN III), ptosis and ophthalmoplegia (CN III, IV, VI), proptosis (superior ophthalmic vein), and anesthesia of the forehead and upper eyelid (CN V1) 1,2 and occurs in

Spontaneous Subdural Fluid Collections following Transection of a Fatty Filum Terminale: Case Report and Review of the Literature

We present the case of a 6-year-old girl who developed bilateral subdural fluid collections following transection of her fatty filum terminale. The patient presented to our emergency department 3 weeks subsequent to surgery, reporting symptoms of headache, nausea, and vomiting. The presence of bilateral subdural fluid collections was confirmed by head computerized tomography. Subdural fluid collections and hematomas have been associated with intracranial hypotension and excessive cerebrospinal fluid leakage; however, there are relatively few cases of subdural fluid collections/hematomas following spine surgery reported in the literature. To our knowledge, this is a unique description of development and resolution of subdural fluid collections following surgical transection of a fatty filum terminale.