18 Intraventricular and Subarachnoid Space Neurocysticercosis
10.1055/b-0036-141993
18 Intraventricular and Subarachnoid Space Neurocysticercosis
Jaime Gerardo Torres-Corzo, Juan Lucino Castillo-Rueda, and Leonardo Rangel-Castilla
18.1 Introduction
Neurocysticercosis (NCC) is the central nervous system (CNS) infection caused by the larval state of the parasite Taenia solum. It is the most common cause of seizures and hydrocephalus in adults in certain regions of the world including Asia, Africa, Eastern Europe, and Central and South America and Mexico, where it is endemic.1,2,3,4 It has become more prevalent in the United States due to the immigration or travel of patients from these regions.4 Two main forms of NCC exist, intraparenchymal and extraparenchymal.3 The intraparenchymal, or benign form, is the most common and is usually treated with antiparasitic drugs. The extraparenchymal, or malignant form, occurs in 30% of cases and involves the basal cisterns, subarachnoid spaces, and/or ventricles. The management of the extraparenchymal form is challenging and requires a combination of medical and surgical treatment.3 It is common to find both forms in the same patient (Fig. 18.1a).
18.2 Pathophysiology
The most common clinical presentation of extraparenchymal NCC is hydrocephalus, which is secondary to direct and indirect obstruction of the cerebrospinal fluid (CSF) pathways. Cysticercal cysts can cause direct mechanical obstruction of the foramen of Monro, cerebral aqueduct, fourth ventricle, or fourth ventricular outlets (Fig. 18.1b–d). Ventricular cysticerci produce an inflammatory reaction of the choroid plexus and ventricular wall, causing ependymitis and ventriculitis with subsequent intraventricular occlusion (Video 18.1and Video 18.2). Parasites in the basal cisterns also produce in intense inflammatory reaction, arachnoiditis, dense exudates formation composed of collagen fibers, lymphocytes, multinucleated giant cells, eosinophils, and hyalinized parasitic membranes leading to abnormal thickening of the leptomeninges extending along the basal cisterns (Video 18.3, Video 18.4, and Video 18.5). Cysticercus cellulosae is a form of thinwalled cyst that could measure up to 20 mm long. This form can involve any region within the CNS but has a predilection for the basal cistern subarachnoid spaces (Fig. 18.1f).4,5,6
Fig. 18.1 (a) Computed tomography (CT) scan showing numerous intraparenchymal calcified cysticercal cysts, multiple racemose cysts at the right of the sylvian fissure, and a large intraventricular cyst in the left occipital horn with associated hydrocephalus. (b) Axial magnetic resonance image (MRI) showing an intraventricular cyst in the right lateral ventricle occluding the foramen of Monro, causing unilateral hydrocephalus. (c,d) Axial and coronal MRI demonstrating the presence of a cysticercal cyst in the anterior portion of the third ventricle, causing obstructive hydrocephalus. (e) Sagittal MRI of a cysticercal cyst in the fourth ventricle, which is causing hydrocephalus and mass effect on the cerebellum. (f) Axial MRI demonstrating multiple racemose cysts in the right temporal fossa, prepontine cistern, and bilateral cerebellopontine angle cisterns; notice the left-to-right brainstem shift due to mass effect.
18.3 Clinical Features
The clinical presentation depends upon the number and location of the lesions. Seizures are the most common clinical manifestation in almost 70% of patients with the parenchymal form. Patients with the extraparenchymal form can present with headache, nausea/vomiting, visual disturbances (blurry vision, diplopia, papilledema), cranial nerve palsies, altered mental status, and other symptoms of increased intracranial hypertension related to hydrocephalus (Fig. 18.1).2,3,7 Cysticercotic encephalitis is a severe form of NCC as result of massive cysticerci infection of the brain parenchyma. Strokes have also been described in ~ 3% of patients because of vasculitis. Some other patients may present psychiatric manifestations ranging from poor performance on neuropsychological testing to severe dementia. Patients with previous ventriculoperitoneal (VP) shunt placement frequently present with signs and symptoms of VP shunt malfunction. The incidence of VP shunt malfunction in patients with NCC varies from 55 to 82% (Video 18.6).8
Video 18.1 Lateral ventricle neurocysticercosis (flexible neuroendoscope). This video demonstrates the endoscopic extraction of cysticercal cysts from the lateral ventricle with a flexible neuroendoscope. The left lateral ventricle is entered, and a very large cysticercal cyst is found to occlude the left foramen of Monro. The cyst is fenestrated and extracted. Next, following the choroid plexus, the endoscope is advanced into the ipsilateral occipital horn, where two cysts are found and extracted. There is evidence of granular inflammatory ependymitis along the ventricular wall. The contralateral ventricle is approached through the septum pellucidum (septum pellucidotomy) and advanced into the occipital horn, where another cysticercal cyst is encountered and extracted. The third ventricle is then approached through the foramen of Monro. A previously performed endoscopic third ventriculostomy is noted. The posterior portion of the third ventricle is reached, and a cyst is found to be occluding the entrance of the cerebral aqueduct. The cyst is extracted.Video 18.2 Third ventricle neurocysticercosis (flexible neuroendoscope). This video demonstrates the endoscopic extraction of a cysticercal cyst from the third ventricle with a flexible neuroendoscope. The large cyst occupies the entire third ventricle. With a grasping forceps passed through the foramen of Monro, the cyst is extracted.Video 18.3 Fourth ventricle neurocysticercosis (flexible neuroendoscope). This video demonstrates the endoscopic extraction of a cysticercal cyst from the fourth ventricle with a flexible neuroendoscope. The endoscope is navigated through the cerebral aqueduct into the fourth ventricle, where a large cysticercal cyst is found. With a grasping forceps the cyst is fenestrated and extracted. Because the large size of the cyst, the endoscope and cyst are withdrawn simultaneously.Video 18.4 Basal cistern neurocysticercosis (flexible neuroendoscope). This video demonstrates the endoscopic extraction of a cysticercal cyst from the basal cistern with a flexible neuroendoscope. A cysticercal cyst located at the premedullary cistern is extracted using the “spaghetti” maneuver (axial rotation of the grasping forceps). The grasping forceps rotates on its axis for better cyst purchase. The endoscope and cyst are withdrawn simultaneously.Video 18.5 Basal cistern neurocysticercosis (flexible neuroendoscope). This video demonstrates the endoscopic extraction of a cysticercal cyst from the basal cisterns with a flexible neuroendoscope. The cysticercal cyst is located between the right vertebral artery and the lower cranial nerves. The cyst is extracted with a grasping forceps.Video 18.6 Intraventricular neurocysticercosis. This video demonstrates an endoscopic ventricular exploration and cyst removal in a patient with intraventricular neurocysticercosis and hydrocephalus. Patient has a previously inserted ventriculoperitoneal shunt that malfunctioned. The right ventricle is approached, and multiple large cysticercal cysts are immediately observed. The free-floating cysts are removed with grasping forceps. Notice the inflammatory reaction on the ependyma (ependymitis) and choroid plexus (plexitis). A second large cyst is removed from the occipital horn.
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