Hyperhomocysteinemia and left internal jugular vein thrombosis with Meniere's symptom complex.

Abstract

The author describes the case of a 68-year-old woman who experienced severe symptoms of Meniere's syndrome. Ultrasonography of the neck detected a clot in the left internal jugular vein. The patient was hospitalized and anticoagulated, and her symptoms soon resolved. The author speculates that the clot-induced hemodynamic changes led to venous insufficiency in the vein of the paravestibular canaliculus and ultimately caused the patient's symptoms. The blood work-up revealed that the patient had an elevated fasting homocysteine level, which is a known risk factor for thrombus formation.

Introduction

Hyperhomocysteinemia is a risk factor for both arterial and venous thrombosis. In this article, the author describes the case of a patient who developed incapacitating Meniere's symptom complex. The work-up revealed a left internal jugular vein thrombosis, and it was later found that the patient had hyperhomocysteinemia. The author postulates that the hyperhomocysteinemia predisposed this patient to clot formation in the left internal jugular vein and this in turn led to the development of the Meniere's symptoms. Once the patient was anticoagulated, her symptoms resolved.

Case report

A 68-year-old white woman had been initially treated by the author for vertigo, left-sided tinnitus, and left-sided aural fullness. During her episodes of vertigo, she experienced nausea, vomiting, and decreased hearing in her left ear. She had no history of trauma or instrumentation to her head and neck. After conservative management with meclizine and methylprednisolone failed to alleviate her symptoms, she was referred to an otolaryngologist.

During the initial referral consultation, findings on a complete head and neck evaluation were within normal limits. Audiometry demonstrated a low-frequency sensorineural hearing loss on the left and some reduction in the patient's speech discrimination scores (84% on the left; 100% on the right). She was diagnosed with Meniere's symptom complex and given dietary instructions.

Despite these measures, the Meniere's symptoms incapacitated the patient to the point where she was unable to work. She next underwent magnetic resonance imaging (MRI) of the brain and magnetic resonance angiography (MRA) of the neck. Findings on MRI were essentially unremarkable, but MRA revealed a possible 60 to 70% stenosis of the right internal carotid artery. The patient was then sent for a Doppler ultrasound study of the carotids. Ultrasonography did not detect any hemodynamic stenosis, but it did show a thrombus in the left proximal internal jugular vein (figure 1). Her protein C and S levels were within normal limits. The patient was hospitalized and anticoagulated with 1 mg/kg of enoxaparin subcutaneously every 12 hours. She was then started on warfarin to achieve an international normalized ratio between 2.0 and 2.5. Once the patient was anticoagulated, her Meniere's symptoms resolved.

[FIGURE 1 OMITTED]

During warfarin anticoagulation, a hematologic evaluation yielded normal values for antithrombin III, lupus anticoagulants, prothrombin gene mutations, antinuclear antibodies, and anticardiolipin antibodies. However, her fasting homocysteine level was elevated at 20.3 [micro]mol/L (range of normal: 4.5 to 12.4). She was started on 1 mg/ day of folic acid and a once-daily multivitamin. She was maintained on warfarin for 6 months and then switched to aspirin at 325 mg/day.

A follow-up ultrasound approximately 2 months after the start of anticoagulation showed no clot in the left internal jugular vein (figure 2). An ultrasound performed approximately 3 months after warfarin was discontinued again did not demonstrate a left internal jugular vein clot (figure 3). The patient remained free of her Meniere's symptoms during her 6 months on anticoagulation, and she remained symptom-free on a regimen of 1 aspirin per day at 15 months of follow-up.

[FIGURES 2-3 OMITTED]

Discussion

Hyperhomocysteinemia can predispose patients to deep vein thrombosis; in this case, the patient's left internal jugular vein was affected. The author postulates that the clot in the left internal jugular vein caused an increase in venous pressure that resulted in venous insufficiency in the vestibular organs. This in turn led to endolymphatic hydrops and the subsequent development of Meniere's symptom complex.

The vein of the paravestibular canaliculus (VPVC) runs parallel to the endolymphatic duct and drains the major portion of the semicircular canals and part of the utricle. The mean width of the paravestibular canaliculus is 0.12 mm. (1) The VPVC receives several veins from the endolymphatic sac and drains into the inferior petrosal sinus or directly into the jugular bulb (figure 4).

[FIGURE 4 OMITTED]

Some research has shown that there are certain variations in the pattern of venous drainage of the vestibular organs. Mazzoni demonstrated that in a certain percentage of human temporal bones, one or two of the vestibular veins drain through the VPVC rather than serving as tributaries of the inferior cochlear vein. (2) Gussen suggested that in these temporal bones, venous insufficiency in the VPVC might produce endolymphatic hydrops. (3) Gussen postulated that increased venous pressure and insufficiency of the vestibular organs could represent the common endpoint of many of the entities known to cause Meniere's disease, although the exact mechanism of increased vestibular venous pressure may differ in each circumstance.

The author postulates that the clot in the left internal jugular vein in this patient altered the blood flow dynamics, which led to increased venous pressure and the resultant venous insufficiency in the VPVC. It is known that the VPVC can drain directly into the jugular bulb. In this patient, the resultant hemodynamic alteration occurring in the left jugular bulb may have disturbed the venous drainage of the endolymphatic duct and/or sac, thereby producing endolymphatic hydrops. In fact, in an article on the surgical lowering of the high jugular bulb in the treatment of 13 patients with Meniere's disease and pulsatile tinnitus, Couloigner et al postulated that the symptoms in these patients were caused by compression of venous drainage of the endolymphatic duct and/or sac by the high jugular bulb. (4) After they surgically lowered the jugular bulb, the symptoms improved, thus adding credence to the importance of venous drainage of the vestibular organs through the VPVC. In the case described here, the effect of the clot in the left internal jugular vein was similar to the effect of a high jugular bulb with respect to the way it altered blood flow dynamics.

The hematologic work-up in the patient described here revealed that she had hyperhomocysteinemia, which increases the risk of clot formation. Hyperhomocysteinemia occurs as a consequence of either (1) the inability of homocysteine to remethylate to methionine or (2) the trans-sulfuration of methionine to cysteine. Folic acid and vitamins [B.sub.6] and [B.sub.12] are important in the processes of remethylation and trans-sulfuration (figure 5). Clot formation is apt to occur in the presence of one or more of Virchow's triad (intimal injury, altered blood flow, and hypercoagulable blood). (5) Hyperhomocysteinemia can cause thrombosis either directly or indirectly. For example, Lentz wrote that homocysteine can inhibit endothelial production of nitric oxide, which has antiplatelet activity and is known to prevent vasoconstriction. (6) Lentz also reported that oxidation of homocysteine can generate reactive oxygen species, such as hydrogen peroxide, superoxide anion, and hydroxyl anion. These reactive oxygen species may impair the endothelium-dependent activation of protein C, thus predisposing a patient to thrombosis. Hyperhomocysteinemia may also stimulate a proliferation of vascular smooth muscle cells.

[FIGURE 5 OMITTED]

The patient described here was treated with folic acid and a daily multivitamin that contained B supplements. Although it is not known whether thrombosis can be prevented with these supplements, she remained clot-free 15 months after the initiation of therapy.

References

(1.) Stahle J, Wilbrand H. The paravestibular canaliculus. Can J Otolaryngol 1974;3:262-70.

(2.) Mazzoni A. Vein of the vestibular aqueduct. Ann Otol Rhinol Laryngol 1979;88(Pt 1):759-67.

(3.) Gussen R. Vascular mechanisms in Meniere's disease. Otolaryngol Head Neck Surg 1983;91:68-71.

(4.) Couloigner V, Grayeli AB, Bouccara D, et al. Surgical treatment of the high jugular bulb in patients with Meniere's disease and pulsatile tinnitus. Eur Arch Otorhinolaryngol 1999;256:224-9.

(5.) Cohen JP, Persky MS, Reede DL. Internal jugular vein thrombosis. Laryngoscope 1985;95:1478-82.

(6.) Lentz SR. Mechanisms of thrombosis in hyperhomocysteinemia. Curr Opin Hematol 1998;5:343-9.

Dr. Scaramella is a family physician in private practice in Chicago. Reprint requests: John G. Scaramella, MD, 4742 N. Austin, Chicago, IL 60630. Phone: [phone]: fax: [phone].