DOI:10.2214/AJR.05.0067
AJR 2005; 185:1664-1665
© American Roentgen Ray Society
Resolution of Temporal Lobe Epilepsy and MRI Abnormalities After Coiling of a Cerebral Aneurysm
Tufail Patankar and
David Hughes
Hope Hospital, Salford, United Kingdom
A 49-year-old known hypertensive woman presented with severe headaches
suggesting subarachnoid hemorrhage (SAH). The headaches were associated with
2-3 episodes of olfactory aura, which she described as smelling like burning
Bakelite. There was no associated nausea, vomiting, or evidence of meningism.
Physical examination and fundi were normal. A CT scan of the brain showed a
left middle cerebral artery (MCA) aneurysm. A lumbar puncture including CSF
spectrophotometry excluded SAH. MRI of the brain showed the aneurysm and
intrinsic temporal lobe changes seen as high signal on FLAIR-weighted images
(Fig. 2A). It was felt that the
temporal lobe epilepsy was caused by the aneurysm and endovascular coiling was
considered appropriate because of the risk of hemorrhage
(Fig. 2B). The aneurysm was
successfully occluded with coils.
The olfactory hallucinations significantly reduced in frequency immediately
after coiling. She was discharged on antihypertensive medications and low-dose
aspirin. Follow-up MRI 6 months after coiling showed good packing of the
aneurysm with a tiny neck recurrence, but the intrinsic signal in the temporal
lobe had resolved (Fig. 2C).
The patient has not suffered from olfactory hallucinations in the 2 years
since coiling.
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Fig. 2C —49-year-old woman with left middle cerebral artery (MCA)
aneurysm. Axial FLAIR MRI of brain after coiling shows resolution of high
signal changes in temporal lobe surrounding coiled aneurysm.
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Temporal lobe epilepsy as a presenting feature of unruptured cerebral
aneurysm is unusual but well recognized
[1,
2]. Aneurysms associated with
epilepsy are usually large and are often of the MCA. Several mechanisms have
been postulated including direct pressure effect, sub-clinical hemorrhage, and
ischemia from thromboembolism as the cause of the seizures
[3].
Vasogenic edema can be observed in the brain parenchyma surrounding a
thrombosed intracranial aneurysm, possibly due to enlargement of acutely
thrombosing aneurysms resulting in loss of vasoresponsivity and ischemia or an
inflammatory process in the brain parenchyma surrounding the thrombosed
aneurysm [4]. No chemical
mediators have yet been linked to perianeurysmal vasogenic edema, and the
exact mechanism remains unclear.
It is also well known that obliteration of the aneurysm can lead to
resolution of seizures, and some authors recommend temporal lobe surgery in
the presence of permanent changes in the adjacent brain
[1,
5].
The white matter changes seen in the temporal lobe may well represent edema
or chronic ischemia, though the predominant white matter involvement and
typical fingerlike appearances would favor vasogenic edema. The resolution of
the temporal lobe signal changes seen on MRI is suggestive of vasogenic edema.
The unique feature in this case is that the resolution seen on MRI correlated
with clinical resolution of the olfactory hallucinations.
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