Hasegawa Y, Morishita M, Ikeda T, Suzumura A
Department of Neurology, Gifu Prefectural Tajimi Hospital, Japan.
Rinsho Shinkeigaku. 1996 Mar;36(3):475-80.
Since treatment of herpes simplex virus encephalitis (HSVE) is most effective when started early, a sensitive and specific method for early diagnosis would be of great benefit. MRI and CT are commonly used for this purpose. In this study, we presented two patients who had serologically confirmed HSVE and had normal CT and MRI, but were diagnosed as having HSVE by means of SPECT in the early stage. Case 1 was a 56-year-old man who suddenly developed alexia. On admission, physical and neurological examination were unremarkable except for alexia, agraphia, acalculia, and left-right disorientation. Brain CT, MRI, and cerebral angiography were all normal. However, SPECT showed hyperaccumulation of 99m Tc-HM-PAO in the right temporal-occipital area. On the 5th hospital day, he became comatose. CSF study revealed marked pleocytosis. Even then, MRI including Gd-enhanced study was normal while SPECT continued to show hyperaccumulation. Detection of herpes simplex virus DNA in CSF by polymerase chain reaction was negative. Anti-HSV antibody titer in CSF and serum confirmed intrathecal production of the antibody on the 14th hospital day. Abnormal accumulation of tracer in SPECT returned to normal on the 31st day when he was alert but still had a mild Gerstman syndrome. Case 2 was a 61-year-old man with disturbance of consciousness, mental dysfunction, and generalized convulsion. He was diagnosed as having HSVE by means of CSF pleocytosis, detection of HSV DNA in CSF by polymerase chain reaction, and presence of anti-HSV antibody in the CSF. CT and MRI again revealed no abnormality while SPECT clearly showed hyperaccumulation in the left temporal lobe in an early stage. Hyperaccumulation of lipophilic tracer on SPECT study, especially in the temporal lobes, has been reported in the early stage of HSVE by previous investigators. Unlike MRI or enhanced CT, the increased tracer accumulation in SPECT does not reflect disruption of the blood-brain-barrier or inflammatory edema, but reflects hyperperfusion or some other HSVE related abnormality which is currently unknown. From these observations, we suggest that local hyperperfusion occurs before local inflammation, and that SPECT is the most useful scanning method for early diagnosis of HSVE when this disease is clinically suspected.
由于单纯疱疹病毒性脑炎（HSVE）的治疗在早期开始时最为有效，因此一种敏感且特异的早期诊断方法将大有裨益。MRI和CT通常用于此目的。在本研究中，我们介绍了两名经血清学确诊为HSVE且CT和MRI正常，但通过SPECT在早期被诊断为HSVE的患者。病例1是一名56岁男性，突然出现失读症。入院时，除失读症、失写症、失算症和左右定向障碍外，体格检查和神经系统检查均无异常。脑CT、MRI和脑血管造影均正常。然而，SPECT显示右颞枕区99m Tc-HM-PAO摄取增加。住院第5天，他陷入昏迷。脑脊液检查显示明显的细胞增多。即便如此，包括钆增强检查在内的MRI仍正常，而SPECT继续显示摄取增加。通过聚合酶链反应检测脑脊液中的单纯疱疹病毒DNA为阴性。脑脊液和血清中的抗HSV抗体滴度在住院第14天证实了抗体的鞘内产生。当他清醒但仍有轻度格斯特曼综合征时，SPECT中示踪剂的异常积聚在第31天恢复正常。病例2是一名61岁男性，有意识障碍、精神功能障碍和全身性惊厥。通过脑脊液细胞增多、聚合酶链反应检测脑脊液中的HSV DNA以及脑脊液中抗HSV抗体的存在，他被诊断为HSVE。CT和MRI再次显示无异常，而SPECT在早期清楚地显示左颞叶摄取增加。先前的研究者报道，在HSVE的早期，SPECT研究中亲脂性示踪剂的摄取增加，尤其是在颞叶。与MRI或增强CT不同，SPECT中示踪剂积聚的增加并不反映血脑屏障的破坏或炎症性水肿，而是反映血流灌注增加或其他目前未知的与HSVE相关的异常。基于这些观察结果，我们认为局部血流灌注增加发生在局部炎症之前，并且当临床上怀疑患有这种疾病时，SPECT是早期诊断HSVE最有用的扫描方法。
