The patient was a 65 year old man who presented with a
seizure after a three day prodrome of abdominal pain, odd smells, and low grade
fever. Six weeks previously he had numbness and tingling of the right arm, face
and leg which resolved. CT scan performed at that time was normal. On
admission, the temperature was 104 degrees F. Spinal fluid from tube #4
contained 113 WBC, 40 RBC, protein 97, and glucose 80. He was treated
empirically with acyclovir, and multiple blood and CSF cultures were negative.
On examination, the patient was awake and alert with good attention, a digit span of seven forward and four backward. His language was fluent and spontaneous, though he perseverated and confabulated. Comprehension of simple verbal commands and word repetition were normal. He was unable to name a wrist watch. Memory was intact to three of three objects at three minutes. He improved dramatically after a three week course of acylovir. Impaired renal function developed, presumed due to acyclovir.
On examination, the patient was awake and alert with good attention, a digit span of seven forward and four backward. His language was fluent and spontaneous, though he perseverated and confabulated. Comprehension of simple verbal commands and word repetition were normal. He was unable to name a wrist watch. Memory was intact to three of three objects at three minutes. He improved dramatically after a three week course of acylovir. Impaired renal function developed, presumed due to acyclovir.
Herpes Simplex Virus(HSV) encephalitis has its own
neuroanatomy. It tends to attack a part of the brain known as the "limbic
system", a set of interconnected brain structures responsible for the
integration of emotion, memory, and complex behavior. This disease is important
to recognize because there is an effective drug treatment, acyclovir.
We will see the limbic system on this tour, as shown by
the lesions of a typical case of HSV encephalitis. HSV is ubiquitous, but
fortunately, only 1 or 2 cases per million infected individuals develop the
encephalitis of HSV each year in the US. It is the most frequently fatal of all
encephalitides.
In this set of images, there is a region of very bright
signal on MR(and high blood flow on SPECT; use the buttons at right) in the
medial temporal lobe at left(patient's right).
This corresponds to an area of active viral leptomeningeal and brain tissue infection. Hemorrhage can occur acutely, but is not seen in this case. You can see obliteration of the temporal horn of the lateral ventricle because of swelling of the hippocampus. The remainder of the brain is relatively hypoperfused(use the buttons at right) and structurally normal. The MR images were obtained 5 days after onset of symptoms, and the follow-up SPECT 23 days later.
This corresponds to an area of active viral leptomeningeal and brain tissue infection. Hemorrhage can occur acutely, but is not seen in this case. You can see obliteration of the temporal horn of the lateral ventricle because of swelling of the hippocampus. The remainder of the brain is relatively hypoperfused(use the buttons at right) and structurally normal. The MR images were obtained 5 days after onset of symptoms, and the follow-up SPECT 23 days later.
