(Stroke. 2000;31:1766.)
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Case Reports |
Facial Palsy in Cerebral Venous Thrombosis
Transcranial Stimulation and Pathophysiological Considerations
From the Departments of Neurology (J.S., M.R.M., T.L.), and Radiology (J.D.), University Hospital of Geneva, Geneva, Switzerland.
Correspondence to Dr J. Straub, c/o Dr M.R. Magistris, Clinique de Neurologie, Hôpital Cantonal Universitaire de Genève, CH-1211 Genève 14, rue Micheli-du-Crest 24, Switzerland. E-mail judith.straub{at}hcuge.ch
Abstract
Background—Cranial nerve palsy in cerebral sinovenous thrombosis (CVT) is rare, its pathophysiology remains unclear, and data from electrophysiological examinations in such patients are missing.
Case Description—We report the case of a 17-year-old woman with familial protein S deficiency who was admitted with extensive multiple CVT. Two weeks after onset of symptoms, she developed isolated right peripheral facial palsy, and MR venography showed segmental occlusion of the ipsilateral transverse sinus. Complete recovery of facial palsy occurred concomitant with recanalization of the transverse sinus. Facial neurography, including transcranial magnetic stimulation of the facial nerve and related motor cortex, ruled out a coincidental idiopathic palsy and revealed conduction block proximal to the facial canal.
Conclusions—Facial palsy in our patient was caused by transient neurapraxia in the intracranial segment of the nerve. We suggest that elevated venous transmural pressure in the nerve’s satellite vein, which belongs to the affected drainage territory of the transverse sinus, might have caused venous blood-brain barrier dysfunction in the intrinsic vascular system of the nerve, with leakage of fluids and ions into the endoneurial space and thus an increase in interstitial resistance.
Key Words: cerebral thrombosis • cranial nerves • neural conduction • protein S deficiency • transcranial magnetic stimulation
The clinical picture of cerebral venous thrombosis (CVT) is variable, and a wide spectrum of neurological symptoms has been described.1 2 3 4 5 Cranial nerve palsy in CVT is rare and is often thought to result from cavernous sinus thrombosis or elevated intracranial pressure.2 4 5 6 7 8 In the early literature, several cranial nerve syndromes in CVT have been identified and attributed to extension of thrombosis into contiguous venous tributaries,2 presumably leading to direct pressure palsy of the nerves lying in proximity to the clot. It is only recently that Kuehnen et al9 have drawn new attention to cranial nerve syndromes in thrombosis of the transverse and sigmoid sinus and suggested that local stasis in the cranial nerve veins draining into the transverse sinus might cause temporary nerve dysfunction.9 This case report of isolated facial palsy in CVT related to protein S deficiency refines their hypothesis, as electrophysiological examination has permitted more insight into the pathogenesis of facial palsy in CVT.
Case Report
We describe a 17-year-old woman with familial protein S deficiency
who began taking oral contraceptives in August 1997. Four months later,
on December 25, she developed a severe headache, with photophobia and
phonophobia, nausea, and neck stiffness, and was hospitalized 2 days
later. Cerebrospinal fluid analysis was normal, but the initial
pressure was not measured. After transient improvement, the headache
worsened despite analgesic treatment, episodes of vomiting occurred,
and bilateral papilledema was noted. Cerebral MRI showed extensive
thrombosis in the territory of the left internal and proximal right
internal cerebral veins, the vein of Galen, and the straight, superior
longitudinal, left transverse, and sigmoid sinuses. High-dose
intravenous heparin and coumarin were initiated, and oral
contraceptives were discontinued. The patient was transferred to our
hospital on January 6, with intense nuchal pain and rigidity,
papilledema with only minimal reduction of visual acuity, and
hyperreflexia. On January 8 she developed right peripheral
facial palsy with lagophthalmus and dry eye without keratitis,
diminished taste, and hyperacusis of the right ear. The palsy was mild
and more marked on the upper part of the face (frontalis and
orbicularis oculi muscles). Bedside otorhinolaryngological examination
ruled out otitis and did not reveal eighth nerve palsy; audiometry was
not performed. Repeat MRI showed persistence of thrombosis in the
above-mentioned sinuses, particularly segmental occlusion of the right
transverse sinus (Figure 1
). There was no
contrast enhancement of the facial nerve and no temporal bone
abnormality (Figure 2). On day 4 after
palsy onset, electrophysiological
examination was performed on a Viking IV electromyography
apparatus (Nicolet), with recordings from
mentalis and nasalis muscles using surface
electrodes.10 11 For both muscles, supramaximal electrical
stimulation (ElStim) was performed in the fossa stylomastoidea, and
magnetic stimulation with a MagStim 200 stimulator (Magstim Company
Ltd) was applied to the ipsilateral mastoidal region (MagStim),
permitting excitation of the facial nerve at its entrance into the
acoustico-facial meatus.12 For the nasalis muscle,
stimulation was also applied to the face-associated motor cortex
(CxStim). The ElStim and MagStim evoked responses were within normal
range on both mentalis and nasalis muscles, whereas the CxStim evoked
response (from nasalis muscle) was markedly reduced in amplitude
compared with the unaffected side (Figure 3). These findings are suggestive
of a partial conduction block of the facial nerve, proximal to its
entrance into the facial canal; normal response to MagStim speaks
against a coincidental idiopathic facial palsy or pressure palsy within
the canal.10 11 The blink reflex R1 and R2 responses
(recorded from orbicularis oculi muscles with stimuli applied to
the supraorbital nerve) showed normal latencies but were reduced in
amplitude on the palsy side.
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Under anticoagulant and analgesic treatment the patient recovered
slowly, and MR venography on January 15 showed partial
recanalization of the right transverse and most of
the other sinuses (Figure 4). The patient
was discharged the next day and had completely recovered from facial
palsy 10 days later. Because the first
electrophysiological examination took place
early and therefore could not completely rule out the subsequent
occurrence of wallerian degeneration, a second recording was
performed. On day 18, when facial palsy had subsided, the ElStim and
MagStim evoked responses remained unchanged. The CxStim response was
delayed and dispersed; amplitude was still reduced.
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Discussion
In our patient, the chronology of events documented by repeat MRI
(Figure 4
), which showed occlusion and later
recanalization of the right transverse sinus
concomitant with onset and recovery from facial palsy, led us to
believe that the palsy was a direct consequence of the right transverse
sinus occlusion. CT of the petrous bones was normal, and MRI showed no
abnormal gadolinium enhancement of the nerve, which may be seen in
facial palsy of other origin.13 Patients with phenotypic
protein S deficiency may develop multiple thromboembolic complications,
including CVT14 15 ; however, there is no mention of
increased incidence of nerve palsies in such patients.
Although involvement of all cranial nerves has been described in CVT,2 3 5 9 16 facial palsy in CVT is very rare and little is known about its pathophysiology. The cranial nerve syndromes identified in the earlier literature have been thought to be caused by pressure palsy, either directly by the thrombotic clot lying in proximity to the nerves5 or by raised intracranial pressure.7 Another explanation for cranial nerve palsy in CVT was given by Kuehnen et al,9 who reported 5 cases of cranial nerve palsy as the only feature of isolated transverse sinus thrombosis. The authors hypothesized that the palsy was due to reversible compromised oxygen or glucose consumption caused by impaired drainage of the cranial nerve veins into the transverse sinus, but no electrophysiologic examination was done to support this hypothesis. In our patient, ElStim and MagStim performed on day 4 after facial palsy onset showed normal responses, whereas both CxStim and blink reflex disclosed markedly decreased amplitudes on the affected side. This indicated a normal conduction within the facial canal and thus discarded a coincidental idiopathic facial palsy10 11 or a pressure palsy within the canal, as might have been suspected from the earlier literature5 and knowledge about the ultrastructure of the nerve.17 18 19 Clinically, the rapid recovery of the nerve function was suggestive of a palsy due to neurapraxia; diminished taste, hyperacusis, and dry eye indicated a suprageniculate blocking. This was confirmed by the electrophysiological findings, consistent with a conduction block of the nerve proximal to the site of excitation that is proximal to its intracanalicular segment.12
In our patient, transmural thrombosis of the distal transverse sinus, which involves the drainage site of the superior petrosal sinus and thus affects the drainage territory of the lateral pontine vein (via the superior petrosal vein),20 21 22 could have raised the intraluminal pressure in the nerve’s satellite vein. Impaired venous drainage of the nerve root’s satellite vein is transmitted to the intrinsic vascular system of the nerve, which consists of segmentally arranged vessels, variable in number and size, that connect with the larger adjacent vessels of the extrinsic system. The postcapillary collecting venules that run in the intraneural septa of the nerve have a lumen lined with endothelial cells connected with tight junctions which represent the venous blood-brain barrier.18 20 22 A rise in venous intraluminal pressure in the extrinsic system can increase the venous transmural pressure in these intraneurial venules and lead to venous blood-brain barrier dysfunction, with leakage of fluids and ions into the endoneurial space.22 Thus, an impairment of the saltatory current flow, with reversible slowing of conduction or even conduction block,23 could account for the neurapraxia proximal to the facial canal observed in our patient. In the fallopian canal, the drainage of the nerve is assured by a widely connected venous network that communicates with the blood vessels of the entire temporal bone. Main vessels empty into the lateral, superior, or inferior petrosal sinuses, the pterygoid plexus of veins, and the middle meningeal veins17 24 and thus provided efficient drainage of the intracanalicular nerve portion. Because the satellite veins of the more caudal cranial nerves drain via the inferior petrosal vein and petrosal sinus distal to the occlusion site into the sigmoid sinus or directly into the jugular vein,21 they also remained unaffected. We suggest that some of the cranial nerve syndromes reported earlier might have been a consequence of similar electrophysiological changes rather than of direct compression or reversible compromised oxygen and glucose consumption.
Acknowledgments
Supported in part by Swiss National Science Foundation Grant 31–53748.98. The authors gratefully acknowledge the editorial assistance of Margaret Asomaning Delteil.
Received February 8, 2000; revision received March 30, 2000; accepted March 30, 2000.
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