Neuro Case 1 – Using Transcranial Doppler for Basilar Artery Occlusion
Welcome to the first of a series of neurological cases to be featured on Brian Blogger. We will periodically choose the most enlightening cases from the Journal of Medical Case Reports (JMCR) for which I serve as an Associate Editor. I will present the case as published, discuss the implications of the findings or techniques employed, and the case author is then asked to comment on our blog to address our readers.
Published by BioMed Central, JMCR “is a peer-reviewed open access journal that will consider any original case report that expands the field of general medical knowledge.” To submit a case report for publication, please review the JMCR submission checklist.
We describe the case of a 79-year-old Caucasian woman with a transient basilar occlusion monitored by transcranial Doppler, with subsequent recanalization and clinical shrinking deficit. [The basilar artery is one of many cerebral vessels that supply the brain, however, unlike the others, it is singular and supplies the brainstem]. This is the first case of transient basilar occlusive disease diagnosed and monitored by transcranial Doppler. This case is important and needs to be reported because transient basilar occlusion may be easily diagnosed if transcranial Doppler is performed.
A 79-year-old woman affected by chronic atrial fibrillation and not treated with oral anticoagulants, cardioverted to sinus rhythm during a gastric endoscopy. She then showed a sudden-onset loss of consciousness, horizontal and vertical gaze palsy [unable to move eyes up-down or sideways], tetraparesis [paralysis of all four extremities] and bilateral miosis [constriction of the pupil] and coma. Two hours later, the symptoms resolved quickly, leaving no residual neurologic deficits. Transcranial Doppler examination showed a dampened flow in the basilar artery in the emergency examination and a restored flow when the symptoms resolved.
This is the first case of transient basilar occlusive disease diagnosed and monitored by transcranial Doppler. We believe that transcranial Doppler should be performed in all cases of unexplained acute loss of consciousness, in particular, if associated with signs of brainstem dysfunctions.
I’ll take this opportunity to describe an invaluable utility in neurology — transcranial Doppler (TCD). This real-time ultrasonic examination measures blood flow through intra-cranial vessels using a probe over the patient’s head. It is inexpensive, quick, and, most importantly, noninvasive. It has been used used in the following clinical applications:
- Sickle Cell Disease — assessing stroke risk
- Intracranial Vasospasm — especially in subarachnoid hemorrhage
- Arterial Stenosis and Occlusion — including testing for recanalization post-treatment
- Monitoring for Sources of Emboli and Heart Shunts during Procedures — detecting microemboli
- Brain Death (Cerebral Circulatory Arrest) — often an adjunct modality
- Testing for Cerebrovascular Autoregulation — testing patients prior to carotid endarterectomy surgery
- Testing for Flow Changes with Cognitive Tasks — akin to MRI and fMRI
In our present case, the patient’s constellation of symptoms (sudden-onset loss of consciousness, horizontal and vertical gaze palsy, tetraparesis and bilateral miosis and coma) is highly indicative of a brainstem lesion most likely of vascular origin. The reticular activating system, a neural network in the brainstem that controls arousal, was presumably affected causing loss of consciousness. The gaze palsy may be explained by involvement of the midbrain and pons. If the cortico-spinal tracts were affected, then tetraparesis is possible. Lastly, a lesion involving hypothalamospinal fibers can triggering bilateral miosis (as in Horner’s syndrome). It is the basilar artery that supplies these territories and its occlusion is associated with the famed locked in syndrome.
In considering acute basilar artery occlusion, cerebral angiography is the gold standard diagnostic test where a neuroradiologist enters the femoral artery with a catheter and reverses his/her way up the brain to illustrate its circulation. However, since the patient’s symptoms resolved and angiography is not without risk including stroke, TCD was performed and revealed “dampened flow” suggestive of recanalization in the case of intracranial artery occlusion. In other words, the presumed embolus that once occluded the basilar artery underwent breakdown (fibrinolysis) and blood flow was re-established. Given that the neurological symptoms completely resolved in less than 24 hours from onset, we would label this event as a transient ischemic attack (TIA).
Diagnosis: Brainstem TIA most likely due to basilar artery embolism diagnosed by TCD
This case illustrates one of the great utilities of TCD — looking at the posterior-circulation of the brain (vertebral-basilar arteries) in acute events for diagnostic purposes. However, the latest application of TCD lies in treating disease, particularly stroke. The TCD ultrasound waves have shown to improve the delivery and penetration of rtPA (the FDA approved clot busting therapy for stroke) inside the clot. This utility, called sonothrombolysis, coupled with special catheters are being studied for acute strokes and look promising.
Nicoletti, G., Albano, G., Sanguigni, S., Tardi, S., Malferrari, G., Del Sette, M., Bruno, F., & Nicolai, A. (2010). Transient basilar artery occlusion monitored by transcranial color Doppler presenting with a spectacular shrinking deficit: a case report Journal of Medical Case Reports, 4 (1) DOI: 10.1186/1752-1947-4-13
Kassab, M., Majid, A., Farooq, M., Azhary, H., Hershey, L., Bednarczyk, E., Graybeal, D., & Johnson, M. (2007). Transcranial Doppler: An Introduction for Primary Care Physicians The Journal of the American Board of Family Medicine, 20 (1), 65-71 DOI: 10.3122/jabfm.2007.01.060128
Rubiera M, & Alexandrov AV (2010). Sonothrombolysis in the management of acute ischemic stroke. American journal of cardiovascular drugs : drugs, devices, and other interventions, 10 (1), 5-10 PMID: 20104930