To the Editors:

In an interesting article, Chandra et al. (2010) quoted us to support the view that the association of neurocysticercosis (NCC) and mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS) is rare. This is not our view. Instead, we believe that this association is rather frequent. NCC is endemic in the developing world, being a major cause of epilepsy worldwide (Garcia et al., 2005). Despite the fact that the epidemiology of the association of MTLE-HS with NCC is unknown, there are some clues regarding the real occurrence of this association. The prevalence of NCC plus MTLE-HS might be high in some world regions (Bianchin et al., 2005). In a cross-sectional study of 512 patients with refractory epilepsy, 281 (54.8%) of them had MTLE-HS and 104 (37.0% of the total of patients with MTLE-HS) presented MTLE-HS plus NCC. In comparison, the prevalence of NCC in patients with other epileptogenic lesions (cortical dysplasia, brain tumors, or gliosis) was only 15%, a significant difference (Velasco et al., 2006). Given the epidemiology of both diseases, if this association also occurs in other populations, then the prevalence of MTLE-HS plus NCC worldwide would be substantial.

So far we believe that there are three possibilities for the association of NCC and MTLE-HS. First, there are patients who have NCC and MTLE-HS because of coincidence (Leite et al., 2000). Second, both diseases might share common predisposing factors, including socioeconomic-related factors (Velasco et al., 2006). Third, NCC might work as an initial precipitating injury leading to typical MTLE-HS, similarly to other infections (Wichert-Ana et al., 2004; Velasco et al.; 2006; Bianchin et al., 2006a). When associated with MTLE-HS, NCC is more common in women than in men, causes more bilateral temporal lobe interictal discharges, and patients tend to have a lower frequency of “classical” initial precipitating injury history (Bianchin et al., 2006b). In addition, NCC in MTLE-HS is anatomically related to the side of the hippocampal sclerosis (Bianchin et al., 2008). Despite these differences, when present, NCC has no major impact on MTLE-HS surgical prognosis (Bianchin et al., 2005), a finding that further supports the role of NCC as an initial precipitating injury. Based on these observations, we suggested that the mechanisms involved in hippocampal damage may be inflammation, repeated seizures involving specific neural networks, NCC-induced status epilepticus, gender-related factors, and possibly other molecular mechanisms (Wichert-Ana et al., 2004; Bianchin et al., 2006a; Velasco et al., 2006; Bianchin et al., 2010). In our view, each of these factors might act separately or together to cause hippocampal damage and MTLE-HS.

Because NCC and MTLE-HS are common diseases, it would not be a surprise if their association were highly prevalent worldwide. Moreover, some data support the view that NCC might directly cause MTLE-HS, favoring this association. Considering its prevalence, NCC could well be a major cause of MTLE-HS. Consequently, it is not possible to state that the association of NCC and MTLE-HS is rare. Further studies are necessary to evaluate the epidemiology of this association and to clarify its mechanisms.


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  2. Disclosure
  3. References

We have no conflict of interest. We confirm that we have read the Journal’s position on issues involved in ethical publication and affirm that this report is consistent with those guidelines.


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  2. Disclosure
  3. References
  • Bianchin MM, Velasco TR, Wichert-Ana L, Alexandre V Jr, Terra-Bustamante VC, Inuzuka LM, Araujo D Jr, Santos AC, Coimbra ER, Escorsi-Rosset SR, Rezek KO, Guarnieri R, Hallak JEC, Walz R, Serafini LN, Fernandes RMF, Assirati JA Jr, Machado HR, Carlotti CG Jr, Markowitsch HJ, Takayanagui OM, Sakamoto AC. (2005) In endemic areas, neurocysticercosis is highly prevalent in patients with mesial temporal lobe epilepsy, but it is not a risk factor for poor surgical outcome or post-surgical cognitive decline. Epilepsia 46(suppl 8): S236.
  • Bianchin MM, Velasco TR, Takayanagui OM, Sakamoto AC. (2006a) Neurocysticercosis, mesial temporal lobe epilepsy, and hippocampal sclerosis: an association largely ignored. Lancet Neurol 5:2021.
  • Bianchin MM, Velasco TR, Araújo D Jr, Alexandre V Jr, Wichert-Ana L, Terra-Bustamante VC, Martins APP, Santos AC, Walz R, Assirati JA Jr, Carlotti CG Jr, Takayanagui OM, Sakamoto AC. (2006b) Clinical and Electrophysiological Differences between Mesial Temporal Lobe Epilepsy and Mesial Temporal Lobe Epilepsy Plus Neurocysticercosis. Epilepsia 47(suppl 4):S244S245.
  • Bianchin M, Velasco T, Araújo D, Wichert-Ana L, Alexandre V Jr, Terra-Bustamante V, Assirati J, Carlotti C Jr, Santos A, Martins A, Rosset S, Leite J, Fernandes R, Takayanagui O, Sakamoto A. (2008) Chronic neurocysticercosis is anatomically related with hippocampal sclerosis in refractory mesial temporal lobe epilepsy plus neurocysticercosis. Epilepsia 49(suppl 7):S487.
  • Bianchin MM, Dal Pizzol A, Cabral LS, Martin KC, Rieder CRM. (2010) Cognitive impairment and dementia in neurocysticercosis: a cross-sectional controlled study. Neurology 75:1028.
  • Chandra PS, Bal C, Garg A, Gaikwad S, Prasad K, Sharma BS, Sarkar C, Singh MB, Padma VM, Tripathi M. (2010) Surgery for medically intractable epilepsy due to postinfectious etiologies. Epilepsia 51:10971100.
  • Garcia HH, Del Brutto OH; Cysticercosis Working Group in Peru. (2005) Neurocysticercosis: updated concepts about an old disease. Lancet Neurol 4:653661.
  • Leite JP, Terra-Bustamante VC, Fernandes RM, Santos AC, Chimelli L, Sakamoto AC, Assirati JA, Takayanagui OM. (2000) Calcified neurocysticercotic lesions and postsurgery seizure control in temporal lobe epilepsy. Neurology 55:14851491.
  • Velasco TR, Zanello PA, Dalmagro CL, Araújo D Jr, Santos AC, Bianchin MM, Alexandre V Jr, Walz R, Assirati JA, Carlotti CG Jr, Takayanagui OM, Sakamoto AC, Leite JP. (2006) Calcified cysticercotic lesions and intractable epilepsy: a cross sectional study of 512 patients. J Neurol Neurosurg Psychiatry 77:485488.
  • Wichert-Ana L, Velasco TR, Terra-Bustamante VC, Alexandre V Jr, Walz R, Bianchin MM, Leite JP, Assirati JA, Carlotti CG, Araújo D, Santos AC, Takayanagui OM, Sakamoto AC. (2004) Surgical treatment for mesial temporal lobe epilepsy in the presence of massive calcified neurocysticercosis. Arch Neurol 61:11171119.