UNDERSTANDING NEUROCYSTICERCOSIS: CAUSES, SYMPTOMS, DIAGNOSIS, TREATMENT AND MORE
Medically Reviewed by Dr. Sony Sherpa, (MBBS)
Neurocysticercosis is a parasitic central nervous system infection caused by the tapeworm Taenia solium. It is considered one of the most common parasitic infections that affect the brain and spinal cord.
Neurocysticercosis is most prevalent in regions with poor sanitation and hygiene practices, such as in the rural communities of Latin America, Africa, and Asia. An estimated 2.56-8.3 million cases of neurocysticercosis exist worldwide, with the highest incidence in rural areas where pigs are prevalent. The impact of neurocysticercosis can be significant, as it is a leading cause of epilepsy in these regions, responsible for 30-70% of cases.[1]
This article discusses the symptoms and underlying causes, including the parasite’s lifecycle, diagnosis, treatment, and long-term management strategies of neurocysticercosis.
What is Neurocysticercosis?
Neurocysticercosis is a parasitic brain condition that arises during the larval stage of an infection by the tapeworm Taenia solium.[2]
The worm reproduces with eggs or in egg-bearing segments known as proglottids. An adult tapeworm can grow between 2-8m in length and deliver as many as 1000 proglottids, each containing up to 50,000 eggs.
When ingested, these mature into adult worms in the intestines, which attach to the gut lining. The eggs or proglottids that break off from the adult tapeworm can either pass through the system or invade the gut lining.
Some eggs pass through to other organs and tissues, like muscles, forming cysts (cysticerci). When the eggs or proglottides invade the nervous system, causing cysts to form, it leads to neurocysticercosis.
There are three stages of neurocysticercosis: vesicular, colloidal, and granular.
- In the vesicular stage, the cysts are small and contain fluid.
- In the colloidal stage, the cysts become inflamed and may cause symptoms.
- In the granular stage, the cysts have calcified and are no longer active, yet may still cause symptoms due to the damage they have caused.
Causes, Transmission, and Risk Factors
The primary cause of neurocysticercosis is ingesting undercooked pork containing tapeworm larvae. The incidence of tapeworm infections is hardly noteworthy amongst communities with high hygiene standards and that do not consume pork.
It is also transmissible with poor hygiene practices, such as food or water contaminated with tapeworm eggs from infected individuals. People living in areas with poor sanitation and hygiene practices have a higher risk of contracting neurocysticercosis, especially where there is insufficient infrastructure.
Occasionally, larvae or eggs are passed on through contaminated soil, especially where pigs are free to roam.
Neurocysticercosis Symptoms
Symptom presentation depends on the location and number of cysts in the brain.
In some patients, one large cyst or group of cysts is confined to a single area, causing localized symptoms. In others, hundreds of little cysts are all over the brain[3], leading to widespread symptoms and complications. Many people with neurocysticercosis do not display any symptoms.
The infection begins in the gut, with symptoms of abdominal pain, cramping, nausea, diarrhea, and constipation while the worms develop (taeniasis). These tend to occur up to 8 weeks after exposure. If left untreated, tapeworms can live inside the gut for 2-3 years or longer.[4]
After cysts spread to the brain, neurocysticercosis develops.
Common symptoms include:
- Headaches
- Seizures
- Perilesional edema (local swelling of brain tissue surrounding the cyst)
- Confusion
- Difficulty with balance and coordination
- Other symptoms related to the brain region affected, such as sensory disturbances
As the cysts grow and cause pressure on the brain, more severe symptoms may develop. The long-term effects of neurocysticercosis vary according to the location and severity of the infection and the effectiveness of treatment.
Complications may include:
- Epilepsy (recurrent seizures)
- Vision problems
- Hydrocephalus or severe fluid buildup in the brain
- Stroke due to blocked blood vessels
- Cognitive impairment due to loss of brain matter
- Paralysis or coma
In some cases, the cysts may also rupture, causing inflammation and further damaging the brain. The complications can be potentially life-threatening.
Prompt treatment is crucial in minimizing the long-term risks associated with neurocysticercosis.
Diagnosis
Neurocysticercosis can be challenging to diagnose, as its symptoms can resemble those of other brain infections, neuro-inflammatory diseases, or brain tumors. It involves a comprehensive evaluation in which a medical professional needs to suspect tapeworms and rule out these other conditions.[5]
A thorough medical history aids the diagnosis, including the patient’s travel history, symptoms, and exposure to risk factors such as undercooked pork. A detailed physical examination also focuses on neurological signs and symptoms that may indicate neurocysticercosis. These initial assessments serve as a guide for further diagnostic evaluations.
Various techniques can confirm the diagnosis of neurocysticercosis:
- A stool sample can almost immediately confirm a tapeworm infection in most patients due to proglottids, yet it cannot distinguish which type is causing symptoms.
- Magnetic resonance imaging (MRI) and computed tomography (CT) scans are neuroimaging techniques that play a crucial role in identifying cysts or lesions in the brain and spinal cord. These imaging tests provide vital information about the location, size, and number.
- Blood tests, including enzyme-linked immunosorbent assays (ELISA), can detect specific antibodies against the parasite. The presence of these antibodies indicates an ongoing infection.
- In some cases, a spinal tap (lumbar puncture) may be necessary to analyze the cerebrospinal fluid for cysticercal antigens or antibodies.
Seeking the assistance of a medical professional with expertise in neurology or infectious diseases is essential for interpreting the diagnostic findings and creating a treatment plan that works for each patient.
Treatment Options
The neurocysticercosis treatment depends on the infection's stage and severity.
It involves a multidimensional approach to reduce symptoms, eliminate the parasite, prevent complications, and manage any associated conditions.[6]
Working together with neurologists, neurosurgeons, infectious disease experts, and other medical specialists, treatment may involve providing all-encompassing care and attending to the patient's individual needs.
It is important to note that the treatment of neurocysticercosis should be tailored to the individual patient and guided by a healthcare professional with expertise in infectious diseases and neurology.
Medication
Antiparasitic medication is a cornerstone of the treatment. Drugs such as albendazole and praziquantel are common prescriptions that kill the parasite and reduce the number of cysts. The duration of treatment can differ on a case-by-case basis. The typical duration for taking albendazole ranges from 8 to 30 days. Reported side effects include stomach pain, nausea, dizziness, and headaches.[7]
In cases where the infection has caused seizures, antiepileptic medications are prescribed to control and prevent seizures. Seizure management is crucial, as recurrent seizures are a common problem associated with neurocysticercosis.
Anti-inflammatories may help reduce inflammation and improve blood flow, lowering the risk for complications like hydrocephalus, cognitive impairment, and stroke.
Surgery
In some instances, surgery may be necessary. Large cysts or cysts in critical locations may require surgical intervention to remove them and relieve pressure on the brain.
Additionally, surgery may be needed to manage complications, particularly fluid buildup in the brain (hydrocephalus), or to treat other associated conditions.
Therapy
If the patient experiences a stroke or related complications such as speech or movement problems, they may benefit from speech therapy, occupational therapy, or physical therapy to help rehabilitate.
Follow-Up
The effectiveness of treatment is regularly monitored through follow-up visits and imaging studies to evaluate the response to therapy and make any necessary adjustments.
Prognosis and Long-Term Management
The prognosis for neurocysticercosis depends on the stage and severity of the infection and the promptness of treatment. If appropriately treated in the early stages, those affected by neurocysticercosis can lead relatively normal lives, and the prognosis is usually good. In more advanced stages, the prognosis may be less favorable, and long-term management may be necessary to prevent potentially deadly complications.
Living with neurocysticercosis can be challenging, as the condition can lead to a spectrum of symptoms and complications. Those with symptoms or long-term infections usually cannot think clearly due to brain inflammation, fluid buildup, etc. Episodic seizures are a common problem that requires long-term management, even after tapeworm is cleared from the gut.
It is important to adhere to a meticulously designed treatment plan as suggested by a medical practitioner and schedule routine examinations. Additionally, support from healthcare providers, family, and friends can assist with managing the physical and emotional challenges associated with neurocysticercosis.
By taking proactive steps and seeking support when needed, individuals with neurocysticercosis can maintain a good quality of life.
Prevention
The best way to prevent neurocysticercosis is to practice good hygiene and avoid consuming raw pork or cook it thoroughly before consumption. Thorough cooking of all meat is essential to avoid tapeworm infections, such as pork, beef, and other animals that can harbor cysts.
The American Center for Disease Control advises the following precautions to prevent tapeworm infections[8]:
- Ensure you clean your hands with soap and warm water after using the restroom, changing a diaper, and before preparing food
- Educate kids about the necessity of hand hygiene to avoid diseases
- All raw perishable foods (i.e., fruits and vegetables) should be washed and peeled before consumption
When journeying in underdeveloped countries, abide by food and water safety guidelines such as:
- Only consume water that is bottled, boiled (for at least a minute), or fizzy drinks from cans or sealed bottles
- To make unsafe water potable, filter it through a filter with a sensitivity of less than 1 micron and use iodine tablets in the filtered water. Absolute 1-micron filters can be sourced from camping and outdoor gear shops
On a global level, prevention and control measures need to encompass the implementation of hygiene standards and infrastructure in endemic areas. Education campaigns and livestock control are other crucial countermeasures to combat tapeworm infections in these areas.
Research Advancements and Vaccines for Neurocysticercosis
Research into neurocysticercosis is ongoing, focusing on developing effective treatments and preventative measures.
One area of research is the development of a vaccine for neurocysticercosis.
There is a vaccine called Cysvax that can prevent neurocysticercosis and related epilepsy. The vaccine stimulates the immune system of pigs to produce antibodies that target the tapeworm, preventing its larval stage from infecting the central nervous system.
In 2016, Cysvax was the first vaccine approved to treat cysticercosis. The Cysvax vaccine has lowered the transmission of tapeworm infection to humans, potentially controlling the prevalence of this parasitic disease.[9]
Scientists are also investigating the creation of a potent vaccine for humans.
Conclusion
Neurocysticercosis is a parasitic central nervous system infection caused by the tapeworm Taenia solium. It is a significant cause of epilepsy among people living in developing countries and can have a substantial impact on individuals and communities. Prompt treatment is crucial in minimizing complications. Ongoing research efforts focus on developing effective treatments and preventative measures that may quell the transmission of tapeworms in the future. Practicing good hygiene and avoiding undercooked pork can help prevent.
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