Spinal Neurocysticercosis

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Epidemiology

• Spinal NC is rare compared with intracranial NC involving the brain, basal cisterns, and ventricles.
• Canelas, et al.,3 reported a 2.7% incidence of spinal NCC in 296 cases of NC.
• Others have suggested that the incidence of spinal NC is as high as 20%.
• However, an incidence of 1.5 to 3% is most often reported.
• Spinal NC occurs in pts with an established diagnosis of intracranial NCC in approximately 75% of the cases
• Isolated cases of spinal NC are thought to be uncommonIsolated cases of spinal NC are thought to be uncommon

Location of Spinal Neurocysticercosis

• Can occur in either the subarachnoid space or parenchyma of the spinal cord
• Subarachnoid location of spinal NC occurs most frequently in approximately 80%
• Intramedullary spinal NC occurs less frequently in the remaining 20% of cas
• An intramedullary location is considered to result from direct hemopoietic spread
• Extradural spinal NC is considered exceedingly rare
• The infrequency of spinal Neurocysticercosis lesions has been considered to be related to CSF reflux at the craniovertebral junction.
• The discrepancy between the expected distribution due to blood flow and reported distribution of Neurocysticercosis lesions remains unexplained.

Signs and symptoms

Spinal neurocysticercosis-related symptoms may depend on several factors including:

• Location (intramedullary compared with subarachnoid)
• Spinal level
• Lesion size
• Presence (or absence) of inflammation and arachnoid scarring due to cyst degeneration
• The most common clinical signs are:
1. Myelopathy
2. Progressive weakness
• Small intramedullary lesions often become symptomatic early
• Extramedullary lesions may become very large and exhibit relatively late and insidious onset of symptoms

Diagnostic Criteria

• Absolute criteria
1. Demonstration of cysticerci by histologic or microscopic examination of biopsy material
2. Visualization of the parasite in the eye by fundoscopy
3. Neuroradiologic demonstration of cystic lesions containing a characteristic scolex
• Major criteria
1. Neuroradiologic lesions suggestive of NC
2. Demonstration of antibodies to cysticerci in serum by enzyme linked immunoelectrotransfer blot
3. Resolution of intracranial cystic lesions spontaneously or after therapy with albendazole or praziquantel alone
• Minor criteria
1. Lesions compatible with NC detected by neuroimaging studies
2. Clinical manifestations suggestive of NC
3. Demonstration of antibodies to cysticerci or cysticercal antigen in CSF by ELISA
4. Evidence of cysticercosis outside the CNS (eg. Cigar shaped soft tissue calcification)
• Epidemiologic criteria
1. Residence in a cysticercosis-endemic area
2. Frequent travel to a cysticercosis- endemic area
3. Household contact with an individual infected with T. solium
• Definitive
1. 1 absolute
2. 2 major
3. 1 major + 2 minor + 1 epidemiological
• Probable
1. 1 major + 2 minor
2. 1 major + 1 minor + 1 epidemiological
3. 3 minor + 1 epidemiological
• Possible
1. 1 major
2. 2 minor
3. 1 minor + 1 epidemiological

Suggested Diagnostic Criteria

• Absolute criteria
1. Histopathological demonstration of the parasite in the tissues obtained from the biopsy of a brain or spinal cord lesion
2. Multiple cystic lesions with or without scolex on CT or MRI

• Major Criteria
1. Lesion highly suggestive of NC in neuroimaging studies
2. Spontaneous resolution or eventual calcification
3. Positive serum EITB assay for the detection of antibodies against T. solium

• Minor criteria
1. Presence of a characteristic clinical picture
2. Positive CSF ELISA
3. Cysticercosis outside the CNS
4. Aggravation of existing symptoms or appearance of a new symptom following anticysticercal therapy

• Diagnosis with caution
1. Old age
2. Pts with pre existing systemic tuberculosis or malignancy
3. HIV infection
4. Grossly abnormal neurological examination

Investigations

• Stool Routine and Microscopy
• Fundoscopy
• Biopsy and histopathology
• MRI
• CT with contrast
• Serology

MRI

• MRI is the diagnostic study of choice for evaluating spinal NC
• On T1-weighted MR images the cyst wall but not the cyst itself can be demonstrated
• MRI with T2-weighted sequences is particularly useful in demonstrating these lesions
• Can also demonstrate pericystic edema in the spinal cord parenchyma.
• Occasionally the actual scolex is visualized on MR images as a mural nodule.

CT

• Myelography and postmyelography CT can be useful for detecting small subarachnoid spinal NC lesions.
• However, myelography may have limited value when there is arachnoidal scarring and obstruction of CSF pathways.
• CT is better than MR imaging for visualizing calcifications associated with degenerated NC cysts.

Serology

• Serological studies are highly sensitive and specific for confirming the diagnosis of NC.
• Rosas has reported that in using the enzyme-linked immunosorbent assay, the sensitivity is 87% and the specificity is 97% for CSF.
• Whereas in serological studies the sensitivity is only 50% and the specificity is only 70%.

Management

• Authors have reported improved outcome when the aforementioned medical therapy was compared with steroid therapy alone.
• Parenchymal NC is considered to be most responsive to pharmacological intervention.
• The efficacy remains unclear when treating subarachnoid, cisternal, or Intraventricular cysticercosis.
• Albendazole may be more effective than praziquantel.
• Garg, et al.,5 reported 2 pts with intramedullary NC in whom improvement was related to albendazole: in one case the pts regained the ability to walk independently and in the other the pts was able to stand independently.
• The inflammatory reaction associated with cyst degeneration in the brain may cause increased intracranial pressure due to obstruction of subarachnoid pathways.
• If medical therapy does indeed cause increased inflammation leading to clinical deterioration as the NC cysts die, then spinal NCC may require surgical therapy as a first line treatment because of the confines of the spinal canal.
• Steroid therapy may ameliorate this by reducing the inflammatory response. Some authors have recommended prescribing medical therapy in all pts with NC
• In pts with localized disease and inflammation- induced symptoms/signs, steroid therapy alone may be adequate treatment.
• Medical treatment of spinal NC appears to be a less viable option because pts with these lesions often present with progressive neurological deficits requiring prompt surgical treatment.

Surgery

• Indication: Cases of spinal NC in which pts experience severe and progressive neurological dysfunction regardless of whether medical therapy has been attempted.
• Resection of intramedullary cysts has the inherent risks associated with surgical treatment of the spinal cord
• Excision of intramedullary NC lesions has been described as being possible after myelotomy or requiring microsurgical dissection from the parenchyma prior to removal.
• Subarachnoid scarring–induced CSF flow obstruction must be treated with duraplasty to re-establish CSF flow.
• Excision of extramedullary lesions is often difficult, needs sharp dissection, gentle irrigation, and Valsalva maneuvers.
• Visualization and localization require ultrasonography to assist.

Clinical outcomes of Spinal Neurocysticercosis

Outcomes in pts with spinal NC are related to the following factors:

• Location
1. Intramedullary or extramedullary
2. Cauda equina or spinal cord levels
• Severity of inflammation
1. Arachnoid scarring or parenchymal injury
• Chronicity of symptoms/time to treatment
• Pts with intramedullary spinal NC lesions appear to experience poorer outcomes.
• Acute neurological deterioration secondary to mass effect is often resolved after prompt excision of the lesion.
• But pts with chronic arachnoidal scarring or spinal cord inflammation may suffer poorer outcomes, despite surgical intervention.
• Pts with NC-induced extrinsic spinal cord and cauda equina compression in the absence of severe arachnoidal scarring appear to have better outcomes than those with intramedullary lesions

Conclusion

• Spinal NC is very rare compared with intracranial NC, which has a relatively high incidence in endemic regions of the world.
• Should be considered in the differential diagnosis in high-risk populations in which patients present with new symptoms suggestive of a spinal mass lesion.
• Subarachnoid spinal NC occurs in 80% of cases, and 20% are intramedullary lesions.
• Signs and symptoms may include myelopathy, radiculopathy, or cauda equina syndrome, depending on location of the cyst.
• The inflammatory arachnoiditis resulting from cyst degeneration may severely limit recovery despite successful excision of the lesion.
• Medical therapy may be considered in patients with stable symptoms but is unlikely to alleviate acute and progressive spinal NC symptoms, which should be addressed surgically.