Answer for BIR CoW 28 Feb 2021
Limbic Encephalitis
Findings
Cortical thickening with T2/FLAIR hyperintensity in the right medial temporal lobe which shows increased signal on DWI and no signal loss in ADC – Limbic Encephalitis. CSF analysis was aseptic. Patient is a known case of CA Breast, post MRM status, hence diagnosis of paraneoplastic limbic encephalitis was made.
Discussion
Autoimmune encephalitis is classified into 2 broad categories, paraneoplastic or non-paraneoplastic, based on the presence or absence of an underlying malignancy, respectively. • paraneoplastic limbic encephalitis: usually antibodies are against intracellular antigens, poor response to immunotherapy • non-neoplastic autoimmune limbic encephalitis: antibodies are against extracellular antigens, usually with a reversible neuronal dysfunction and better outcomes Paraneoplastic syndromes affecting the CNS are generally thought to develop in cancer when antigens shared by tumor cells and native non-neoplastic neuronal cells result in an antibody-mediated attack on previously immune-privileged neuronal structures. Paraneoplastic syndromes are most often seen in small-cell lung cancer but can also be seen in a variety of other cancers as well, such as neuroblastoma, germ cell tumor of the testis, breast cancer, Hodgkin lymphoma, thymoma, and immature ovarian teratomas. There is a clear predilection in autoimmune encephalitis for antigens within the limbic system. Imaging Findings – MRI Early during the course of the disease there may not be any specific findings. The most common location of involvement is the mesial temporal lobes and limbic systems, typically manifested by cortical thickening and increased T2/FLAIR signal intensity of these regions. Bilateral involvement is common, although often asymmetric. The lateral temporal lobe and insula are less commonly involved, whereas the basal ganglia, in contrast, are frequently involved. Although far less common, essentially any part of the central nervous system can be involved. Patchy areas of enhancement may be seen post contrast. True diffusion restriction (i.e. low ADC values) and hemorrhage are not common. Differential diagnosis • herpes simplex encephalitis o acute, often dramatic time course o fever o psychiatric symptoms uncommon o bilateral asymmetrical involvement of the limbic system, medial temporal lobes, insular cortices and inferolateral frontal lobes. o basal ganglia spared o Restricted diffusion common • status epilepticus o acute, often dramatic time course o Common locations involved are cerebral cortex and subcortical white matter, hippocampi and mesial temporal lobes, thalamus. • tumor o low-grade astrocytoma if localized to the temporal lobe, appearances can be very similar o gliomatosis cerebri diffuse T2 hyperintensity involving multiple contiguous lobes no predilection for the limbic system
Findings
Cortical thickening with T2/FLAIR hyperintensity in the right medial temporal lobe which shows increased signal on DWI and no signal loss in ADC – Limbic Encephalitis. CSF analysis was aseptic. Patient is a known case of CA Breast, post MRM status, hence diagnosis of paraneoplastic limbic encephalitis was made.
Discussion
Autoimmune encephalitis is classified into 2 broad categories, paraneoplastic or non-paraneoplastic, based on the presence or absence of an underlying malignancy, respectively. • paraneoplastic limbic encephalitis: usually antibodies are against intracellular antigens, poor response to immunotherapy • non-neoplastic autoimmune limbic encephalitis: antibodies are against extracellular antigens, usually with a reversible neuronal dysfunction and better outcomes Paraneoplastic syndromes affecting the CNS are generally thought to develop in cancer when antigens shared by tumor cells and native non-neoplastic neuronal cells result in an antibody-mediated attack on previously immune-privileged neuronal structures. Paraneoplastic syndromes are most often seen in small-cell lung cancer but can also be seen in a variety of other cancers as well, such as neuroblastoma, germ cell tumor of the testis, breast cancer, Hodgkin lymphoma, thymoma, and immature ovarian teratomas. There is a clear predilection in autoimmune encephalitis for antigens within the limbic system. Imaging Findings – MRI Early during the course of the disease there may not be any specific findings. The most common location of involvement is the mesial temporal lobes and limbic systems, typically manifested by cortical thickening and increased T2/FLAIR signal intensity of these regions. Bilateral involvement is common, although often asymmetric. The lateral temporal lobe and insula are less commonly involved, whereas the basal ganglia, in contrast, are frequently involved. Although far less common, essentially any part of the central nervous system can be involved. Patchy areas of enhancement may be seen post contrast. True diffusion restriction (i.e. low ADC values) and hemorrhage are not common. Differential diagnosis • herpes simplex encephalitis o acute, often dramatic time course o fever o psychiatric symptoms uncommon o bilateral asymmetrical involvement of the limbic system, medial temporal lobes, insular cortices and inferolateral frontal lobes. o basal ganglia spared o Restricted diffusion common • status epilepticus o acute, often dramatic time course o Common locations involved are cerebral cortex and subcortical white matter, hippocampi and mesial temporal lobes, thalamus. • tumor o low-grade astrocytoma if localized to the temporal lobe, appearances can be very similar o gliomatosis cerebri diffuse T2 hyperintensity involving multiple contiguous lobes no predilection for the limbic system
Note:
We do not discourage differential diagnosis. But all the differentials must satisfy the findings noted in the case.
If you feel you have answered rightly but cannot find your name in the above list, please call 09551942599.
Did you Know?
The order in which the names appear in this winner's list is based on the time of submission. The first person to send the correct answer gets his/her name on top of the list!
We do not discourage differential diagnosis. But all the differentials must satisfy the findings noted in the case.
If you feel you have answered rightly but cannot find your name in the above list, please call 09551942599.
Did you Know?
The order in which the names appear in this winner's list is based on the time of submission. The first person to send the correct answer gets his/her name on top of the list!