Extra-cranial venous flow in patients with multiple sclerosis.

INTRODUCTION: Recently, a chronic state of impaired venous drainage from the central nervous system, termed chronic cerebrospinal venous insufficiency (CCSVI) was claimed to be a pathologic condition exclusively seen in patients with multiple sclerosis (MS), suggesting that cerebral venous congestion plays a significant role in the pathogenesis of MS. This hypothesis has gained enormous attention among patients and physicians but has been questioned since. METHODS: Twenty seven patients with MS and 32 healthy controls underwent color extra cranial Doppler exam aimed to detect four parameters of abnormal venous flow: no Doppler-detected flow in the IJV or vertebral veins (VV), reflux in the internal jugular veins (IJVs), venous flow stenosis in the IJVz (cross sectional area <0.3 cm) or reverted postural control in the IJV. RESULTS: Except for one healthy patient, blood flow direction in the IJVs was normal in all subjects. When aiming to detect at least one parameter of abnormal venous flow per subject, two parameters or three parameters no significant difference was found between subjects and controls (p = 0.707, 0.62, 0.849 respectively). CONCLUSION: We found no evidence to suggest that MS patients have excess of CCSVI. In addition we failed to observe a typical venous flow pattern in MS patients. Until carefully designed controlled studies to investigate CCVSI have been completed, invasive and potentially dangerous endovascular procedures as therapy for MS should be discouraged.

Cold pressor test in tetraplegia and paraplegia suggests an independent role of the thoracic spinal cord in the hemodynamic responses to cold.

BACKGROUND: Cold application to the hand (CAH) is associated in healthy people with increase in heart rate (HR) and blood pressure (BP). OBJECTIVE: To study hemodynamic responses to CAH in humans following spinal cord injuries of various levels, and examine the effect of spinal cord integrity on the cold pressor response. DESIGN: An experimental controlled study. SETTING: The spinal research laboratory, Loewenstein Hospital, Raanana, Israel. SUBJECTS: Thirteen healthy subjects, 10 patients with traumatic T(4-6) paraplegia and 11 patients with traumatic C(4-7) tetraplegia. MAIN OUTCOME MEASURES: HR, BP, HR and BP spectral components (low frequency, LF; high frequency, HF; LF/HF), cerebral blood flow velocity (CBFV) and cerebrovascular resistance index (CVRi). METHODS: The outcome measures of the three subject groups monitored for HR, BP and CBFV were compared from 5 min before to 5 min after 40-150 s of CAH. The recorded signals were digitized online and analyzed offline in both the time and frequency domains. RESULTS: During CAH, HR and CVRi increased significantly in all subject groups (P<0.001), and BP in control subjects and in the tetraplegia group (P<0.01). BP increase was not statistically significant in paraplegia, and CBFV, HR LF, HR HF and BP LF did not change significantly during CAH in any group. CONCLUSIONS: The CAH effect in tetraplegia and the suppressed BP increase in paraplegia, supported by the other findings, suggest a contribution of an independent thoracic spinal mechanism to the cold pressor response.

Modified cold pressor test by cold application to the foot after spinal cord injury: suggestion of hemodynamic control by the spinal cord.

OBJECTIVE: Study hemodynamic responses to cold application to the foot (CAF) to explore the autonomic cardiovascular control by the spinal cord. DESIGN: Controlled experimental study. Hemodynamic variables were measured or calculated for 13 healthy subjects, 10 patients with traumatic T4-T6 paraplegia, and 11 patients with traumatic C4-C7 tetraplegia. Subjects were continuously monitored for heart rate (HR), blood pressure (BP), and cerebral blood-flow velocity (CBFV) from 5 mins before to 5 mins after 40-120 secs of CAF by ice water foot immersion. The recorded signals were digitized online and analyzed offline in the time and frequency domains. RESULTS: During CAF, HR increased in the control group but decreased in patients (P < 0.001). BP increased significantly in the control and tetraplegia groups (P < 0.001) and nonsignificantly in the paraplegia group. HR and BP spectral components (LF, HF, LF/HF) did not change significantly. CBFV increased significantly in the patient groups (P < 0.05) but not in the control subjects. The cerebrovascular resistance increased significantly in the control and tetraplegia groups (P < 0.001), but not in the paraplegia group. CONCLUSIONS: The findings support the presence of hemodynamic autonomic control by the spinal cord and show that responses to CAF can be used to assess its integrity.

Hemodynamic effects of liquid food ingestion in mid-thoracic paraplegia: is supine postprandial hypotension related to thoracic spinal cord damage?

BACKGROUND: Postprandial hypotension (PPH) appears in various conditions with autonomic failure and was symptomatic in a patient with thoracic paraplegia, but was not remarkable in patients with tetraplegia. OBJECTIVE: To determine whether the pathology causing PPH may include a thoracic but not a cervical spinal cord lesion (SCL). DESIGN: An experimental controlled study. SETTING: The spinal research laboratory, Loewenstein Hospital, Raanana, Israel. SUBJECTS: Thirteen healthy subjects, 10 patients with traumatic T(4)-T(6) paraplegia, and 11 patients with traumatic C(4)-C(7) tetraplegia. MAIN OUTCOME MEASURES: Heart rate (HR), blood pressure (BP), HR and BP spectral components (LF, HF, LF/HF), cerebral blood flow velocity (CBFV), and cerebrovascular resistance index (CVRi). METHODS: The effects of a standard liquid meal on the outcome measures were compared between the three subject groups monitored for HR, BP, and CBFV, from 55 min before to 45 min after the start of the meal. The recorded signals were digitized online and analyzed off-line in the time and frequency domains. RESULTS: After meal, BP decreased only in the paraplegia group (P<0.01), HR increased more prominently in this group (P<0.01), CVRi tended to decrease only in the paraplegia group, CBFV did not change significantly in any group, and HR LF/HF increased (P<0.001) in all groups but tended to increase more in paraplegia. CONCLUSIONS: Patients with mid-thoracic SCL may develop PPH. The pathology causing PPH can include a thoracic but not a cervical SCL. The normal hemodynamic reaction to liquid meal ingestion is mediated through the mid-thoracic spinal cord. The sympathovagal balance increases after food ingestion, more prominently in patients with PPH, and cerebrovascular resistance changes during PPH may help maintain the cerebral circulation.

Spatially Resolved Observation of Static Magnetic Flux States in YBa2Cu3O7-dgr Grain Boundary Josephson Junctions.

With low-temperature scanning electron microscopy, the magnetic flux states in high critical temperature Josephson junctions have been imaged. The experiments were performed with YBa(2)Cu(3)O(7-delta) thin-film grain boundary Josephson junctions fabricated on [001] tilt SrTiO(3) bicrystals. For applied magnetic fields parallel to the grain boundary plane, which correspond to local maxima of the magnetic field dependence of the critical current, the images clearly show the corresponding magnetic flux states in the grain boundary junction. The spatial modulation of the Josephson current density by the external magnetic field is imaged directly with a spatial resolution of about 1 micrometer.

The use of transcranial Doppler in the hemodynamic assessment of implanted pacemakers.

Twenty patients with DDD pacemakers had their intracranial cerebral circulation assessed in different pacing modes, using transcranial Doppler. The studies were performed at the vertebral artery in a sitting position. Although DDD pacing was preferred to VVI pacing in 18 of the 20 patients, the figures did not reach statistical significance. There was no statistical difference in maximal blood flow velocity between DDD pacing at 60 and 80 beats/min. Varying the AV interval from 150-250 msec also demonstrated no clear difference in maximal peak Doppler velocity, in the group as a whole, though there was a greater individual preference for 150 msec. Transcranial Doppler assessment of the hemodynamics of the cerebral circulation is of limited value as an indicator of mode or rate preference in the pacemaker population.