Findings that shed new light on the possible pathogenesis of a disease or an adverse effect

CASE REPORT

Sudden worsening after subdural haematoma
surgery: will there be a corpus callosum injury?
Pier Paolo Panciani,1 Elena Roca,1 Giovanni Lodoli,2 Marco Maria Fontanella1
1

Department of Neuroscience,
Division of Neurosurgery,
University of Brescia, Brescia,
Italy
2
Department of Neuroscience,
Division of Diagnostic Imaging,
University of Brescia, Brescia,
Italy
Correspondence to
Dr Pier Paolo Panciani,
pierpaolo.panciani@gmail.com
Accepted 8 May 2014

SUMMARY
We report a case of mild encephalopathy with a
reversible splenial lesion (MERS) which occurred after
chronic subdural haematoma (CSDH) surgery. The patient
was admitted to our hospital for drowsiness and marked
asthenia. The cerebral CT scan revealed a CSDH and
surgery allowed to improve the symptoms, but after
several days we observed a sudden worsening. The
patient developed left-sided myoclonic seizures followed
by left hemiplegia and worsening drowsiness.
Electrolytes imbalance and inflammatory causes were
excluded. The CT scan showed a right cerebral swelling
and the subsequent MRI revealed a single lesion in the
splenium of the corpus callosum, hyperintense on
diffusion-weighted images. After osmotic therapy the
patient improved and on day 10 of admission the MRI
showed a complete resolution of the lesion. This is the
first report that described an association between CSDH
and MERS. Possible aetiopathogenetic mechanisms are
discussed.

right-sided CSDH with significant midline shift
(figure 1A).
The haematoma was immediately evacuated
(figure 1B) and the postoperative course was
uneventful. Suddenly, on the fourth day after
surgery, he had a stroke-like worsening consisting
of drowsiness, fever and left-sided myoclonic seizures. After 4 h, we observed a left hemiplegia.
Inflammatory markers (white cell count, C reactive protein and procalcitonin) and electrolytes (performed daily until clinical improvement) were
within normal limits. The ECG was performed
while the twitches were present which allowed to
exclude a status epilepticus.
The cerebral CT revealed a right-sided brain
swelling with increased midline shift (figure 1C).
After a few hours we decided to perform MRI that
showed a severe vasogenic brain oedema and a
corpus callosum lesion (figure 2A–D).

INVESTIGATIONS
BACKGROUND
Mild encephalopathy with a reversible splenial
lesion (MERS) is a rare disease defined radiologically as a lesion in the corpus callosum involving at
least the splenium. Pathognomonic signs of MERS
on MRI are T2 signal prolongation and restricted
water diffusion with decreased apparent diffusion
coefficient values in the splenium.1
Two types of MERS are described. Type 1 is
characterised by an isolated reversible lesion in the
corpus callosum. In type 2, the lesion is extended
to the entire corpus callosum and may involve the
surrounding white matter.2
The aetiopathogenesis is still debated. Viral infections and genetic factors leading to an electrolyte–
water imbalance are usually reported. In our
experience, a reversible splenial lesion occurred
after surgery for evacuation of a chronic subdural
haematoma (CSDH) in a healthy adult man.

▸ The cerebral MRI showed brain oedema and a
single lesion in the corpus callosum characterised by T2 signal prolongation and restricted
water diffusion with decreased apparent diffusion coefficient values (figure 2A–D).
▸ The subsequent cerebral MRI, performed
after clinical recovery of the patient, showed the
complete resolution of the splenial lesion
(figure 2E–H).

DIFFERENTIAL DIAGNOSIS
The differential diagnosis of MERS includes acute
disseminated encephalomyelitis, ischaemia, infections, traumatic injury, multiple sclerosis, posterior
reversible encephalopathy syndrome, lymphoma
and extrapontine myelinolysis.
The clinical and radiological courses were consistent with the diagnosis of MERS. We supposed
that MERS was a direct consequence of the brain
swelling hence the other hypothesis was excluded.

TREATMENT
CASE PRESENTATION

To cite: Panciani PP,
Roca E, Lodoli G, et al. BMJ
Case Rep Published online:
[please include Day Month
Year] doi:10.1136/bcr-2013203278

A 52-year-old immunocompetent man was hospitalised for drowsiness and marked asthenia. The
patient presented with a Glasgow Coma Scale
(GCS) of 15 and no cognitive impairment was
detected. The neurological examination showed no
sensory or motor deficits.
The clinical history revealed a progressively worsening headache which occurred about 1 month
before. Neither comorbidities nor previous infections were reported. The cerebral CT showed a

Panciani PP, et al. BMJ Case Rep 2014. doi:10.1136/bcr-2013-203278

We decided to perform an osmotic therapy that
allowed to quickly improve the symptoms. We used
dexamethasone 16 mg/day for 1 week that lead
both to reducing of the cerebral swelling and the
resolving of the splenial lesion.

OUTCOME AND FOLLOW-UP
Patients with MERS generally recover completely.3
As a matter of fact, our patient showed a good
outcome and he was discharged after 15 days
without neurological deficits. The postoperative
1

Findings that shed new light on the possible pathogenesis of a disease or an adverse effect

Figure 1 Cerebral CT scan showing a chronic subdural haematoma with midline shift (A). Postoperative CT scan after 1 day (B). Four days after
surgery, the CT scan showed a cerebral swelling (C).
long-term follow-up (6 months) was uneventful and the cerebral
MRI did not reveal any lesion.

DISCUSSION
CSDH presents a high incidence, especially in the elderly.4
Surgery is usually mandatory and prognosis is generally good. In
our case, we observed an unexpected clinical worsening after
surgery. The patient did not present risk factors usually related to
CSDH surgery failure. As a matter of fact, the anamnesis was
negative for antiplatelet and anticoagulant therapy, bleeding
diathesis and other cardiovascular or haematological disorders.
We performed MRI to exclude vascular events, but we observed
a severe brain oedema associated to an unexpected likely MERS.
The stroke-like occurrence of the symptoms may be due to
the vasogenic oedema that acted as a trigger event for the
MERS onset. We supposed that the corticosteroids allowed to
improve the symptoms, because they were effective for the vasogenic oedema and the intramyelinic lesion.5
Patients harbouring MERS are usually affected by bacterial
(Salmonella enteritidis, Enterococcus faecalis) or viral infections

(influenza A and B, Epstein-Barr virus, adenovirus and
rotavirus).3 However, in our patient neither bacterial nor viral
infections were revealed.
Other non-infectious causes were described such as trauma,
cerebellitis, hyponatremia, chemotherapy, antiepileptic drugs
and high-altitude cerebral oedema.3 6 Notebaert et al3 in a
recent study reviewed clinical, biochemical and microbiological
data of patients with MERS and hypothesised that the variety of
pathological events will expand in the future. As a matter of
fact, our experience showed that MERS may be due to CSDH
surgery.
The pathogenesis is still unknown. Some theories have been
proposed including vascular impairment, direct viral invasion
and arginine vasopressin suppression, but the mechanism of
transiently splenial reduced diffusion is currently debated.7
Intramyelinic oedema due to inflammatory infiltration and
hyponatremia may be a trigger event.8 This should lead to oxidative stress resulting in a reversible white matter lesion.6
In our case a significant cerebral swelling was observed after
CSDH evacuation. Changes in the intracranial pressure and

Figure 2 Axial and sagittal T2-weighted and axial diffusion-weighted images (A–C) showing brain oedema and an high-signal lesion in the central
splenium of the corpus callosum, apparent diffusion coefficient (ADC) map (D) showing considerably reduced ADC value. Three weeks after onset,
T2-weighted images (E and F), axial diffusion-weighted image (G) and ADC map (H) showing a complete resolution of the lesions.
2

Panciani PP, et al. BMJ Case Rep 2014. doi:10.1136/bcr-2013-203278

Findings that shed new light on the possible pathogenesis of a disease or an adverse effect
brain re-expansion may be related to that occurrence. We
hypothesised that haemodynamic factors, such as sustained
vasodilation, impaired cerebral autoregulation, elevated cerebral
capillary pressure and induced hypoxia lead to cerebral oedema.
We suppose that the cerebral swelling was the main cause of
the sudden clinical deterioration. Furthermore, we speculate
that it might have acted as a trigger event for MERS occurrence
as supposed in a case of high altitude cerebral oedema.6 9 10
The resulting electrolyte–water imbalance could be responsible
for the reduced diffusion observed in MRI.

Learning points

Competing interests None.
Patient consent Obtained.
Provenance and peer review Not commissioned; externally peer reviewed.

REFERENCES
1

2

3
4

▸ Clinical worsening after chronic subdural haematoma (CSDH)
evacuation is usually due to the occurrence of a status
epilepticus, electrolyte disorders and infectious agents. We
speculate that cerebral swelling, which may lead to mild
encephalopathy with a reversible splenial lesion, should be
hypothesised as a possible reversible complication in case of
neurological deterioration after CSDH surgery.
▸ A diffusion-weighted MRI allows to easily detect splenial
lesions.
▸ The osmotic therapy may lead to achieving a complete
recovery.

5

6
7

8

9

Acknowledgements Dr Rosaria Rotunno, MD (Department of Neuroscience,
Division of Neurosurgery) for the great application in the preparation of the
manuscript.

10

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Kometani H, Kawatani M, Ohta G, et al. Marked elevation of interleukin-6 in mild
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