Tractography of Persistent Ipsilateral Hemiparesis
Following Subdural Hematoma

BRIEF COMMUNICATIONS

Seong-il Oh, Mi-Jung Kim, Kyung-Pil Oh, Hyun Young Kim, Seung Hyun Kim, Hee-Jin Kim

Can J Neurol Sci. 2013; 40: 601-602

Ipsilateral hemiparesis is occasionally caused by a medullary
lesion or by secondary damage to the cerebral peduncle
contralateral to the lesion, a so-called Kernohan-Woltman notch
phenomenon (KWNP). A possible mechanism of ipsilateral
hemiparesis is that morphological changes in the brainstem
associated with KWNP are accompanied by irreversible damage
to the adjacent corticospinal tract (CST).1-3 A few reports dealing
with the acute and sub-acute stages of this paradoxical
phenomenon have appeared in the literature.1,2,4,5
In the case reported here, the patient presented with longstanding ipsilateral hemiparesis following traumatic subdural
hematoma 16 years previous. We investigated and visualized
using fiber tractography (FT) permanent reconfiguration of the
CST contralateral to the lesioned side with midbrain atrophy.
CASE REPORT

A 55-year-old male with right hemiparesis visited the
neurology clinic. His medical records revealed that he had been
admitted with stuporous mentality after a head trauma 16 years
previous. At that time he had a Glasgow Coma Scale of 14 with
quadriparesis. Brain computed tomography (CT) showed a large
acute subdural hematoma in the fronto-temporo-parietal area of
the right hemisphere with midline shift. Decompressive
craniectomy with hematoma removal was performed. Although
he gradually recovered motor power in the left extremity, right
hemiparesis was sustained. He was discharged with a residual
right hemiparesis and revisited the hospital due to medical
insurance requirements 16 years afterward. He complained of
dysarthria and spastic hemiparesis. On neurological examination,
the motor strengths of the right extremities were a grade 3 on the
Medical Research Council (MRC) scale. Deep tendon reflexes
were hyperactive in the right extremities. There were no
symptoms related to any of the sensory modalities.
Conventional magnetic resonance (MR) images as well as
diffusion tensor images (DTIs) were obtained with a 3.0 T MR
imaging scanner (Philips Real Time Compact Magnet 3.0-Tesla
MRI system, Achieva 3.0-Tesla X-series) using an 8-element
phased-array neurovascular array coil. Fluid-attenuated inversion
recovery (FLAIR) images showed asymmetric shrinkage of the
right hemisphere and ventricular enlargement in the temporal
horn (Figure 1A). Asymmetric loss of volume of the left cerebral
peduncle in the midbrain was also apparent (Figure 1B).
Diffusion tensor images were obtained using a sequence of
single-shot spin-echo-type echo-planar images (TR/TE,
13891/55ms; matrix size, 112×112; FOV, 224 mm; 90 axial
sections; 2.0-mm section thickness). At the level of the
supratentorial CST on the lateral view, significant degenerated

From the Department of Neurology (SIO, KPO, HYK, SHK, HJK), Rehabilitation
Medicine (MJK), College of Medicine, Hanyang University, Seoul, Republic of Korea.
RECEIVED OCTOBER 12, 2012. FINAL REVISIONS SUBMITTED JANUARY 2, 2013.
Correspondence to: Hee-Jin Kim, Department of Neurology, College of Medicine,
Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul, 133-791, Republic of
Korea. Email address: hyumcbrain@hanyang.ac.kr.

THE CANADIAN JOURNAL OF NEUROLOGICAL SCIENCES

601

https://doi.org/10.1017/S031716710001475X Published online by Cambridge University Press

Figure: Brain MRI and fiber tractography. (A) FLAIR images show
asymmetric shrinkage of the right hemisphere and ventricular
enlargement in the temporal horn (arrow). (B) Mild asymmetric loss of
volume of the left cerebral peduncle in the midbrain can be seen (open
arrow). (C, D) Fiber tractography of the corticospinal fiber from the
lateral view(C: right lateral view; D: left lateral view). The corticospinal
fiber in the tractography of the left hemisphere shows severe
degeneration (D), while the corticospinal fiber of the right hemisphere is
intact (C).

CSTs were observed in the left side, while those of the right side
were intact (Figure 1C, D).

DISCUSSION

Kernohan-Woltman notch phenomenon, which was first
described by Kernohan and Woltman, refers to the paradoxical
association between an ipsilateral motor deficit and deformation

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in the contralateral cerebral peduncle.3 A wide range of serious
injuries can increase intracranial pressure and cause
development of Kernohan's notch. The morphological changes
of KWNP may correlate with indentation of the cerebral
peduncle caused by midbrain compression or irreversible tissue
damage to the CST in the cerebral peduncle. In the acute and
subacute stages of KWNP, ipsilateral hemiparesis may be due to
pathological mechanisms, e.g. compressive forces that cause the
herniating midbrain to impinge on the contralateral edge of the
tentorium cerebelli, contralateral contusion, pressure necrosis
secondary to elevated intracranial pressure, or arterial
infarction.1-4
In this case, after the primary lesion was relieved,
degeneration of the CST contralateral to the cerebral peduncle
may have been sustained in the compressed free tentorial notch
due to the characteristics of the CST, a discrete and compact
collection of a large number of axons; interestingly, in the
present patient, these axons may have extended for more than a
meter from their cell bodies. Another possible mechanism of
persistent disruption to the myelinated fibers of the CST in
KWNP could be failure of compensatory fiber regeneration.
Fiber tractography revealed that the CST of the right
hemisphere was intact, while long-term Wallerian degeneration,
potentially caused by the pressure effect of the subdural
hematoma, not by parenchymal damage, as well as midbrain
atrophy, was observed in the left hemisphere.
In summary, fiber tractography suggested a good diagnostic
evidence for investigating the possible mechanism of
uncommonly consolidated features of ipsilateral hemiparesis and
the distribution of degenerated fibers.
ACKNOWLEDGEMENTS

Authors Seong-il Oh and Mi-Jung Kim contributed equally to
this work.
This study was supported by the cluster research fund of
Hanyang University (HY-2009-C). There is no conflicts of
interest in this study.

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https://doi.org/10.1017/S031716710001475X Published online by Cambridge University Press

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