Keywords overdrainage - spinal dural enhancement - ventriculoperitoneal shunt - cervical myelopathy
- vertebral venous system - craniocervical junction
Palavras-chave hiperdrenagem - alargamento dural espinhal - derivação ventriculoperitoneal - mielopatia
cervical - sistema venoso vertebral - junção craniocervical
Introduction
The typical clinical manifestations of cerebrospinal fluid (CSF) overdrainage include
orthostatic headache, nausea, vomiting, neck pain, diplopia and blurred vision.[1 ] Brain magnetic resonance imaging (MRI) findings related to spontaneous intracranial
hypotension (SIH) are rather variable: diffuse pachymeningeal enhancement associated
with pituitary enlargement, optic chiasm flattening, increased anterioposterior diameter
of the brainstem, and engorged cerebral venous sinuses may be encountered. Spinal
MRI revealing an extra-arachnoid fluid collection, extradural extravasation of fluids,
meningeal diverticula, diffuse pachymeningeal enhancement, and enlargement of the
spinal epidural venous plexus are not uncommon,[2 ] but compressive cervical myelopathy related to the epidural venous plexus engorgement
caused by fluid hypotension is extremely rare.[3 ]
[4 ]
[5 ]
[6 ]
[7 ]
[8 ]
[9 ]
[10 ]
[11 ]
This paper reports the case of a patient who presented a progressive cervical myelopathy
related to an epidural venous plexus engorgement caused by shunt overdrainage. Since
an early diagnosis was never reached, this case report covers the primary findings
and pitfalls before the primary etiology was revealed.
Case Report
Case history: A 33-year-old woman was admitted to our service presenting a two year
history of clinical cognitive progressive deficit, associated with visual alterations,
episodes of loss of strength in the upper right limb, weakness in the lower limbs,
and urinary retention. Both brain MRI and computed tomography (CT) exams revealed
a communicating hydrocephalus associated with cortical atrophy ([Fig. 1 ]). Routine blood tests detected anemia, under only the hematological evaluation,
thus the apparent cause of the anemia was not encountered.
Fig. 1 Axial (A) and sagittal (B) T1-weighted MRI revealing a communicating hydrocephalus.
The patient was submitted to a ventriculoperitoneal (VP) shunt with a high-pressure
system. She developed a headache, which improved in repose, and control CT scans showed
a well-positioned valve with reduction of the ventricular cavity.
Approximately two years after the VP shunt implant was done, neck pain, headache and
visual deficit worsened, accompanied by quadriparesis and paresthesia.
A cervical MRI evidenced the presence of an anterior cervical mass leading to significant
spinal cord compression ([Fig. 2 ]), and a brain MRI showed the absence of hydrocephalus. Angioresonance showed a significant
enlargement of the epidural venous plexus ([Fig. 3 ]). The VP shunt overdrainage hypothesis had not been considered until then.
Fig. 2 MRI images of the cervical spine two years after the VP shunt. T1-weighted (A), T2-weighted
(B) and gadolinium-enhanced T1-weighted (C, D) demonstrating spinal cord compression
at C2-C5.
Fig. 3 Cervical angioresonance demonstrating internal vertebral venous plexus engorgement,
especially of the anterior compartment.
In another service, the patient was submitted to the replacement of the shunt system
by a programmable pressure valve, and evolved to a progressive improvement in the
neurological symptoms.
The control cervical MRI at one year revealed the complete absence of the cervical
epidural mass ([Fig. 4 ]).
Fig. 4 Sagittal cervical T1-weighted (A) and T2-weighted (B) MRI one year after surgery,
demonstrating no spinal cord compression and no engorgement of the cervical venous
plexus.
Discussion
Venous drainage at the craniocervical junction flows through the internal jugular
vein and vertebral veins with contribution of their associated anastomoses. The anterior
and posterior condylar veins form the plexus of the vertebral vein, but this may be
modified by the presence of emissary anastomoses of the mastoid, with an increased
possibility of drainage at this level. The veins of the junction are formed by the
confluence of the emissary and posterior cephalic veins with the superior epidural
venous system.[12 ]
The contribution of the internal jugular veins for cerebral drainage is variable among
individuals, with a possible venous flow ranging all the way from 6 to 72%.[13 ] The epidural cervical venous system is located in the anterolateral portion of the
spinal channel, and it may function as an alternative to the cranial drainage system,
possibly affecting the intracranial pressure in some cases. It is equivalent to an
independent accessory venous drainage system of the intracranial compartment.
The vertebral venous system may be divided into anterior and posterior sections, respectively
consisting of the intraspinal epidural venous plexus and the external posterior paravertebral
system.[14 ] Functional variations may occur depending on the flexion or extension and position
of patient's head.
Intracranial hypotension syndrome is characterized by postural headache and low fluid
pressure. It may be classified into five types: primary or spontaneous; post lumbar
puncture; cranial post-trauma; post-craniotomy; and severe depletion of volume. Ventriculoperitoneal
shunt overdrainage is also thought to be another cause of intracranial hypotension
syndrome.[15 ]
Schaltenbrand[16 ]
[17 ] introduced the concept of SIH and proposed three mechanisms to explain its pathophysiology:
1) decreased CSF production; 2) CSF hyperabsorption; or 3) CSF leak.
Spinal manifestations of SIH occur in nearly 6% of patients, and may involve all spinal
levels with either myelopathy or radiculopathy. Diagnosis is not only difficult; in
many cases, it is also late, given the infrequent spinal image evaluation, not counting
the fact that nearly 20% of brain MRIs present as normal.[18 ] Findings on brain MRI regarding SIH are variable. Diffuse pachymeningeal enhancement;
pituitary enlargement; increased antero-posterior diameter of brainstem; subdural
fluid collection; and engorged cerebral venous sinuses may be observed. Extra-arachnoid
fluid collection, extradural extravasation of fluid, meningeal diverticula, diffuse
pachymeningeal enhancement, and engorgement of the spinal epidural venous plexus may
be noted in the spinal MRI.[2 ]
The diffuse dural enhancement is considered to be the result of venous dilation caused
by low CSF volume. According to what Monro-Kellie advocates, the intracranial volume
of CSF is inversely related to the cerebral blood volume. For this reason, in SIH
cases, a decreased CSF volume leads to an increase in the dural venous blood volume
and consequent venous enlargement.[19 ] This mechanism results in dural thickening and enhancement. The Monro doctrine may
be applied to the vertebral channel, as both cavities, cranial and spinal, are closed
systems.[8 ]
[20 ]
Förderreuther et al were able to demonstrate through cervical MRI the cervical epidural
veins' dilation during orthostatic headache crises, with subsequent improvement and
remission of those signs once the pain subsided.[20 ] Ciceri showed evidence of vein dilation in Hirayama myelopathy cases.[21 ] The epidural venous plexus engorgement has been described as another cause of radicular
compression,[22 ]
[23 ]
[24 ] and SIH was also shown to be a cause of dilation of the epidural venous plexus.[1 ]
In an extensive review of the literature, not more than 10 related cases have been
found – this present case included – where a cervical venous plexus engorgement results
from shunt overdrainage ([Table 1 ]). In 1998, Miyazaki et al were the first to describe the clinical manifestation
of myelopathy in the overdrainage of a VP shunt system in a patient with a low-pressure
shunt after subarachnoid hemorrhage.[8 ] In the cases described, the time interval to the onset of overdrainage symptoms
after shunt placement was quite variable. An interesting observation regards the initial
manifestations of myelopathy, which varied from 4 months to 10 years.[3 ]
Table 1
Cases described in the literature and results
Literature
Sex/
Age
Pathology
Symptoms/
time after VP shunt
Radiological findings
Treatment
Results
Miyazaki et al[8 ]
M/53
SAH
Quadriparesis/
-
Spinal cord compression CCJ-C3
Ligation of VP
shunt
Improvement
Matsumoto et al[7 ]
M/67
Pineal tumor
Paraparesis/
2 years
Cranial diffuse meningeal enhancement
Removal of the shunt
Improvement
Wingerchuk et al[11 ]
F/72
Posterior fossa meningioma
Quadriparesis/
-
Cervical enhancement
Refused treatment
Unchanged
Liu et al[5 ]
F/18
Porencephalic cyst
Quadriparesis/
4 months
Engorgement of the epidural veins
Change to programmable shunt
Improvement
Humphries et al[4 ]
F/33
Dandy-Walker
Paraparesis/
-
Engorgement of the epidural C2-C5
Change revision
Improvement
Wolfe et al[10 ]
M/17
Tumor cyst
Quadriparesis/
5 years
Dilated epidural venous plexus
Change to programmable shunt
Improvement
Martínez-Lage et al[6 ]
F/20
Communicating hydrocephalus
Neck and back pain/
-
Lesion mimicking cervical epidural hematoma C1-C5
No surgical treatment
Improvement
Ulrich et al[9 ]
F/17
Obstructive hydrocephalus
Paraparesis/
4 years
Engorgement of the cervical epidural venous plexus C2-C3
Change to anti-siphon device, valve pressure increased
Improvement
Cardoso et al[3 ]
M/32
Communicating
hydrocephalus
Quadriparesis/
10 years
Engorgement of the cervical venous plexus CCJ and intracranial
Change to programmable shunt
Improvement
Dantas et al (present study)
F/33
Communicating hydrocephalus
Quadriparesis/
2 years
Spinal cord compression by engorgement of the cervical venous plexus C2-C5
Change to programmable shunt
Improvement
Abbreviations: CCJ, craniocervical junction; F, female; M, male; SAH, spontaneous
subarachnoid hemorrhage; VP, ventriculoperitoneal.
Also noteworthy is the fact that no cases described in the literature have presented
the classic symptoms of CSF overdrainage. The majority of patients have presented
with motor deficit clinical symptoms (9 cases), and only 1 case presented with neck
and back pain.[6 ] The present case initially presented with headache, which improved in repose, and
with neck pain after light trauma, further evolving into the known fluid hypotension
and compressive cervical myelopathy symptoms.
Surgical treatment was needed in eight cases. Shunt system replacement was the most
common occurrence, and clinical improvement was observed in all cases after surgery.
There was one case in which treatment was refused,[11 ] and another patient who only underwent clinical follow-up.[6 ] Complications such as the above mentioned illustrate a rare clinical presentation
of VP shunt failure, reinforcing that adequate knowledge of this pathology is paramount
to its early identification.
Conclusion
This case is an interesting presentation of clinical failure of the shunt, with overdrainage
involving the cervical venous plexus and venous cerebral drainage. The engorgement
of the cervical venous plexus should always be kept in mind during differential diagnoses
of myelopathy in patients with shunt and clinical signs of overdrainage.
