Unilateral or bilateral punctate hippocampal hyperintensities
on DW-MRI: seizures, amnesia, or both?
Juan Carlos Garcia-Monco
Received: 3 January 2018 /Accepted: 30 May 2018
Springer-Verlag Italia S.r.l., part of Springer Nature 2018
The presence of small hippocampal hyperintense lesions on diffusion-weighted (DW) MRI can respond to different etiologies
and represents a challenge where clinical judgment is imperative, since therapeutic approach may be quite different.
We here report three patients with similar neuroradiological findings, i.e., hyperintense punctate hippocampal lesions on
diffusion-weighted MRI sequences, yet of different origin. The first one presented with isolated amnesia (transient global
amnesia), the second one with amnesia and seizures, and the third one with seizures.
Thus, hippocampal punctate lesions appear after transient global amnesia, but the same pattern may be present after seizures,
either focal-onset or generalized seizures. This peculiar radiological MRI pattern could indicate a pathogenic link between
transient global amnesia (TGA) and seizures which should be further studied.
Transient global amnesia
Magnetic resonance imaging
The presence of small hippocampal hyperintense lesions on
diffusion-weighted (DW) MRI can respond to different etiol-
ogies and represents a challenge where clinical judgment is
In 10–30% of patients with transient global amnesia
(TGA), small punctate hyperintense foci are seen in the hip-
pocampus, but similar changes may also appear after seizures,
thus complicating the differentiation of both disorders and
perhaps suggesting a pathophysiological link.
The hippocampal formation has a special vulnerability to
different neurological conditions such as ischemia, TGA, sei-
zures, encephalitis, Alzheimer’s disease, trauma, and metabol-
ic derangements [1, 2]. Although hippocampal restricted dif-
fusion lesions with low apparent diffusion coefficient (ADC)
values may appear in these conditions, the presence of a punc-
tate lesion suggests TGA or seizures.
A 75-year-old woman, without relevant medical history pre-
sented to the emergency department with sudden-onset disori-
entation, anterograde amnesia, and repetitive questioning.
Brain CT scan was normal, as were blood and urine tests,
and a lumbar puncture. She recovered 12 h after onset but
experienced amnesia of the episode. An EEG was normal.
Brain DW-MRI (Fig. 1a) at 59 h showed two small foci of
restricted diffusion on both hippocampi, radiologically consis-
tent with a diagnosis of TGA. The patient was lost to follow-
A 55-year-old male was admitted to the emergency depart-
ment with a first convulsion. His past medical history revealed
a viral encephalitis in childhood without sequelae and no his-
tory of febrile seizures. Ten hours before admission, he repeat-
edly experienced repetitive brief episodes of altered con-
sciousness with abnormal feelings of familiarity (dèjá vu phe-
nomena) and anterograde amnesia followed by a generalized
tonic-clonic seizure. The picture was consistent with a partial
seizure evolving to generalized tonic-clonic activity. CSF
* Juan Carlos Garcia-Monco
Departmenf of Neurology, Hospital de Galdakao-Usansolo,
48960 Galdakao, Vizcaya, Spain