History
Neurocysticercosis is a pleomorphic disease, although it sometimes produces no clinical manifestation. This pleomorphism is due to variations in the locations of the lesions, the number of parasites, and the host's immune response. [3]
Many patients are asymptomatic; others report vague symptoms such as headache or dizziness. The onset of symptoms is usually subacute to chronic, with the exception of seizures, which present in an acute fashion. Possible symptomatic presentations are briefly reviewed below.
Epilepsy
Epilepsy is the most common presentation (70%) of neurocysticercosis and is also a complication of the disease. [14] Neurocysticercosis is the leading cause of adult-onset epilepsy and is probably one of the most frequent causes of childhood epilepsy in the world.
Seizures secondary to neurocysticercosis may be generalized or partial. Simple and complex partial seizures may be associated with the presence of a single lesion. Generalized seizures are usually tonic-clonic; this is thought to be related to the presence of multiple lesions. However, irritation of focal cortical tissue by one of the lesions most probably leads to focal onset with secondary generalization. Myoclonic seizures also have been described.
Go to First Adult Seizure for complete information on this topic.
Headache
Headaches may be associated with intracranial hypertension and are indicative of hydrocephalus; they may also result from meningitis. Chronic headaches may be associated with nausea and vomiting (simulating migraines).
Intracranial hypertension
Most often, intracranial hypertension is due to obstruction of cerebrospinal fluid (CSF) circulation caused by basal or ventricular cysticercosis. It may also result from large cysts displacing midline structures, granular ependymitis, arachnoiditis, or the so-called cysticercotic encephalitis caused by the inflammatory response to a massive infestation of cerebral parenchyma with cysticerci. Affected patients may have seizures and deterioration of their mental status, mainly due to the host's inflammatory reaction as an exaggerated response to the massive infestation.
Diplopia may also result from intracranial hypertension or arachnoiditis producing entrapment or compression of cranial nerves III, IV, or VI.
Strokes
Ischemic cerebrovascular complications of neurocysticercosis include lacunar infarcts [15] and large cerebral infarcts due to occlusion or vascular damage. Hemorrhage can also occur and has been reported as a result of rupture of mycotic aneurysms of the basilar artery. Strokes may be responsible for paresis or plegias, involuntary movements, gait disturbances, or paresthesias. [16]
Neuropsychiatric disturbances
Neuropsychiatric dysfunction can range from poor performance on neuropsychologic tests to severe dementia. These symptoms appear to be related more to the presence of intracranial hypertension than to the number or location of parasites in the brain.
Hydrocephalus
Ten to thirty percent of patients with neurocysticercosis develop communicating hydrocephalus due to inflammation and fibrosis of the arachnoid villi or inflammatory reaction to the meninges and subsequent occlusion of the foramina of Luschka and Magendie. Noncommunicating hydrocephalus may be a consequence of intraventricular cysts.
Presentations of other forms of neurocysticercosis
Patients with intrasellar neurocysticercosis present with ophthalmologic and endocrinologic manifestations mimicking those of pituitary tumors.
Spinal neurocysticercosis is rare and may be either intramedullary or extramedullary. The extramedullary form is the most frequent and is responsible of symptoms of spinal dysfunction such as radicular pain, weakness, and paresthesias. Intramedullary presentation may cause paraparesis, sensory deficits with a level, and sphincter disturbances.
Ocular cysticercosis occurs most commonly in the subretinal space. Patients may present with ocular pain, decreased visual acuity, visual field defects, or monocular blindness.
Systemic cysticercosis is most common in the Asian continent. The parasites may be located in the subcutaneous tissue or muscle. Peripheral nerve involvement as well as involvement of the liver or spleen have been reported.
Physical Examination
Twenty percent or less of infected patients with neurocysticercosis have abnormal neurologic findings. Physical findings depend on where the cyst is located in the nervous system and include the following:
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Cognitive decline
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Dysarthria
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Extraocular movement palsy or paresis
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Hemiparesis or hemiplegia, which may be related to stroke, or Todd paralysis
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Hemisensory loss
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Movement disorders
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Hyper/hyporeflexia
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Gait disturbances
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Meningeal signs
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Massive nonencephalitic neurocysticercosis. Photo courtesy of Cysticercosis Working Group in Peru.
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Computed tomographic (CT) scan of the brain in a patient who presented with an episode of generalized tonic-clonic seizure. Note the calcified lesion in the left parieto-occipital region. Subsequent evaluation confirmed the diagnosis of neurocysticercosis.
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T2-weighted magnetic resonance image (MRI) of the brain showing the presence of increased signal as a result of edema in the right frontal region; subsequent studies found a cysticercus in that location.
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Magnetic resonance image (MRI) of the brain in a patient who presented with an episode of generalized tonic-clonic seizure. Note the cyst in the left parieto-occipital region with perilesional edema.
