RE: Congenital Dilatation of the Cervical Epidural Venous Plexus: Neuroradiology and Endovenous Management

To the Editor:

With great interest we read the report by Dr. Rodiek et al. about a 15-year-old obese girl, complaining of cervicobrachialgia, vertigo, headache and transient numbness and weakness in both hands. The authors concluded that this was caused by congenital dilatation of the cervical epidural venous plexus, and decided to occlude the veins that are draining the right cavernous and petrous sinus into the suboccipital venous plexus. Acute resolution of the complaints was not obtained, but pain reduced substantially during the following 18 months. Interestingly, in the mean time the patient had reduced weight [[4]]. Although not specified to the reader, this particular note suggests that weight reduction has been substantial. We suppose that the girl otherwise was healthy, without any internal/hormonal disease (i.e., hypothyroidism).

The human vertebral venous system is a large valveless collateral network that is composed of the internal (or epidural) vertebral venous plexus (IVVP) and the external (or perivertebral) vertebral venous plexus (EVVP). The IVVP communicates with the intracranial basilar venous plexus (anteriorly), which joins both the petrosal and cavernous sinuses, and the occipital sinus, marginal sinus and thus the confluens sinuum (posteriorly). Via the segmental spinal (intervertebral) veins the IVVP connects with the vertebral veins, the inferior vena cava, the ascending lumbar veins and the azygos and hemiazygos veins. This makes the IVVP an important cerebral venous outflow tract and a valveless anastomotic system that also serves as a volume/pressure regulator between intra-thoracic, intra-abdominal, intra-cranial and spinal venous channels [[1] [2] [3]].

Rodiek et al. listed a number of conditions/diseases that were reported to have caused dilatation of the IVVP (see Tab. 1) [[4]]. Since the IVVP is a valveless anastomotic venous system, dilatation of this pathway can occur when there is an obstruction somewhere else in the venous outflow tracts. The obstruction and/or obliteration of the normal venous drainage via the jugular and/or the vertebral veins has not been mentioned in the Table, but the significance of such a condition is illustrated in a recent publication by Vardiman et al. [[5]]. They reported a patient with cervical myelopathy from dilated anterior cervical IVVP due to bilateral stenosis of the internal jugular vein [[5]]. Taking into consideration the radiological illustrations in Dr. Rodiek's report (showing tiny vertebral veins [see Fig. 2]) and the clinical course after embolisation (no immediate relief of the symptoms, despite of “permanent occlusion of the embolised feeders”), it might very well be that a similar mechanism i.e., outflow obstruction (anatomical [stenosis]) and/or mechanical [compression]) of the jugular and/or vertebral veins was present in their patient [[4]]. A finding that supports this is the increased flow within the epidural veins, as was recorded by the authors with duplex ultrasound [[4]]. The obesity of the girl might have caused (mechanical) venous obstruction, since significant improvement of her complaints was noticed simultaneously with weight-reduction, 18 months after the endovenous procedure. To elucidate this, detailed study of the (anterograde) venous drainage (intra- and extra-cranially) after cerebral arteriography is necessary, but unfortunately such data are not provided by Dr. Rodiek et al. in their paper.

Phlebography of the jugular vein (see Fig. 2 [[4]]) is not informative in this context, since it is a retrograde venous technique [[4]]. It seems that the authors were only focussed on the dilated cervical IVVP, without searching for the cause of this phenomenon.

We assume that cerebral venous drainage in this adipose patient predominantly occurred via the IVVP, which in it self may explain volume expansion and dilatation of those vessels. The complaints of headache, vertigo and cervicobrachialgia (although neurologically very atypical) can be the result of venous congestion in the posterior fossa and the cervical spinal canal. The dilatation of the cervical IVVP may be regarded as an attempt by the body to warrant and to facilitate venous drainage of the cranial structures via an alternative (anatomical) venous pathway. Consequently, endovascular occlusion of veins that are connecting the intracranial sinuses and the IVVP (as has been attempted by the authors) seems incorrect, since this compromises cranial venous drainage even more.

Based on the data that are supplied in the present paper, the concept of obesity-related obstruction of the main outflow tracts (i.e., the jugular and vertebral veins) seems a plausible alternative explanation for the dilatation of the cervical IVVP and for the clinical course in this patient. As such, reduction of (over-)weight has decreased outflow obstruction of the jugular and/or vertebral veins and thus resulted in decompression of the suboccipital and cervical IVVP. Vardiman et al. performed a venous bypass of the stenotic jugular veins, which resulted in improvement of the neurological condition of their patient [[5]].

References

• 1 Clemens H J. Die Venensysteme der menschlichen Wirbelsäule. Morphologie und funktionelle Bedeutung. Berlin: Walter de Gruyter & Co 1961
• 2 Groen R JM, Groenewegen H J, Van Alphen H AM, Hoogland P VJM. The morphology of the human internal vertebral venous plexus. A cadaver study after intravenous Araldite CY 221 injection.  Anat Rec. 1997;  249 285-294
• 3 Herlihy W F. Revision of the venous system: the role of the vertebral veins.  Med J Aus. 1947;  1 661-672
• 4 Rodiek S O, Schmidhuber H, Lumenta C B. Congenital dilatation of the cervical epidural venous plexus: neuroradiology and endovenous treatment.  Minim Invas Neurosurg. 1999;  42 69-73
• 5 Vardiman A B, Dickman C A, Spetzler R F, Heiserman J E, Thompson B G. Cervical myelopathy from dilated epidural veins: case report of intracranial outflow obstruction treated with sigmoid sinus-to-internal jugular vein bypass.  BNI Quart. 1999;  14 (3) 13-17