Repaired coarctation of the aorta, persistent arterial hypertension and the selfish brain

BACKGROUND

It has been estimated that 20-30% of repaired aortic coarctation (CoA) patients develop hypertension, with significant cardiovascular morbidity and mortality. Vertebral artery hypoplasia (VAH) with an incomplete posterior circle of Willis (ipCoW; VAH + ipCoW) is associated with increased cerebrovascular resistance before the onset of increased sympathetic nerve activity in borderline hypertensive humans, suggesting brainstem hypoperfusion may evoke hypertension to maintain cerebral blood flow: the "selfish brain" hypothesis. We now assess the "selfish brain" in hypertension post-CoA repair.

METHODS

Time-of-flight cardiovascular magnetic resonance angiography from 127 repaired CoA patients (34 ± 14 years, 61% male, systolic blood pressure (SBP) 138 ± 19 mmHg, diastolic blood pressure (DBP) 76 ± 11 mmHg) was compared with 33 normotensive controls (42 ± 14 years, 48% male, SBP 124 ± 10 mmHg, DBP 76 ± 8 mmHg). VAH was defined as < 2 mm and ipCoW as hypoplasia of one or both posterior communicating arteries.

RESULTS

VAH + ipCoW was more prevalent in repaired CoA than controls (odds ratio: 5.8 [1.6-20.8], p = 0.007), after controlling for age, sex and body mass index (BMI). VAH + ipCoW was an independent predictor of hypertension (odds ratio: 2.5 [1.2-5.2], p = 0.017), after controlling for age, gender and BMI. Repaired CoA subjects with VAH + ipCoW were more likely to have difficult to treat hypertension (odds ratio: 3.3 [1.01-10.7], p = 0.049). Neither age at time of CoA repair nor any specific repair type were significant predictors of VAH + ipCoW in univariate regression analysis.

CONCLUSIONS

VAH + ipCoW predicts arterial hypertension and difficult to treat hypertension in repaired CoA. It is unrelated to age at time of repair or repair type. CoA appears to be a marker of wider congenital cerebrovascular problems. Understanding the "selfish brain" in post-CoA repair may help guide management.

JOURNAL SUBJECT CODES

High Blood Pressure; Hypertension; Magnetic Resonance Imaging (MRI); Cardiovascular Surgery; Cerebrovascular Malformations.

Spinal tophaceous gout encasing the thoracic spinal cord

Gout rarely compresses the thoracic spinal cord. A 43-year-old man presented with lower limb paraparesis. MRI showed a soft tissue swelling at the level of T10/T11. He was managed with a laminectomy and evacuation of a presumed abscess and started on intravenous antibiotics. However, histology confirmed tophaceous gout.

The dura causes spinal cord compression after spinal cord injury

MR scans from 65 patients with traumatic spinal cord injury were analysed; on admission 95% had evidence of cord compression - in 26% due to the dura, and in the remaining 74% due to extradural factors. Compression due to dural factors resolved with a half-life of 8.7 days. These findings suggest that bony decompression alone may not relieve spinal cord compression in the quarter of patients in whom dural factors are significant.

Intraspinal pressure and spinal cord perfusion pressure after spinal cord injury: an observational study

OBJECT

In contrast to intracranial pressure (ICP) in traumatic brain injury (TBI), intraspinal pressure (ISP) after traumatic spinal cord injury (TSCI) has not received the same attention in terms of waveform analysis. Based on a recently introduced technique for continuous monitoring of ISP, here the morphological characteristics of ISP are observationally described. It was hypothesized that the waveform analysis method used to assess ICP could be similarly applied to ISP.

METHODS

Data included continuous recordings of ISP and arterial blood pressure (ABP) in 18 patients with severe TSCI.

RESULTS

The morphology of the ISP pulse waveform resembled the ICP waveform shape and was composed of 3 peaks representing percussion, tidal, and dicrotic waves. Spectral analysis demonstrated the presence of slow, respiratory, and pulse waves at different frequencies. The pulse amplitude of ISP was proportional to the mean ISP, suggesting a similar exponential pressure-volume relationship as in the intracerebral space. The interaction between the slow waves of ISP and ABP is capable of characterizing the spinal autoregulatory capacity.

CONCLUSIONS

This preliminary observational study confirms morphological and spectral similarities between ISP in TSCI and ICP. Therefore, the known methods used for ICP waveform analysis could be transferred to ISP analysis and, upon verification, potentially used for monitoring TSCI patients.

Expansion duroplasty improves intraspinal pressure, spinal cord perfusion pressure, and vascular pressure reactivity index in patients with traumatic spinal cord injury: injured spinal cord pressure evaluation study

We recently showed that, after traumatic spinal cord injury (TSCI), laminectomy does not improve intraspinal pressure (ISP), spinal cord perfusion pressure (SCPP), or the vascular pressure reactivity index (sPRx) at the injury site sufficiently because of dural compression. This is an open label, prospective trial comparing combined bony and dural decompression versus laminectomy. Twenty-one patients with acute severe TSCI had re-alignment of the fracture and surgical fixation; 11 had laminectomy alone (laminectomy group) and 10 had laminectomy and duroplasty (laminectomy+duroplasty group). Primary outcomes were magnetic resonance imaging evidence of spinal cord decompression (increase in intradural space, cerebrospinal fluid around the injured cord) and spinal cord physiology (ISP, SCPP, sPRx). The laminectomy and laminectomy+duroplasty groups were well matched. Compared with the laminectomy group, the laminectomy+duroplasty group had greater increase in intradural space at the injury site and more effective decompression of the injured cord. In the laminectomy+duroplasty group, ISP was lower, SCPP higher, and sPRx lower, (i.e., improved vascular pressure reactivity), compared with the laminectomy group. Laminectomy+duroplasty caused cerebrospinal fluid leak that settled with lumbar drain in one patient and pseudomeningocele that resolved completely in five patients. We conclude that, after TSCI, laminectomy+duroplasty improves spinal cord radiological and physiological parameters more effectively than laminectomy alone.

Patient-controlled intracranial pressure for managing idiopathic intracranial hypertension

Idiopathic intracranial hypertension is a difficult condition to manage. We present a novel treatment that substantially improved the headaches and reduced admissions and shunt revision surgery in a patient. We inserted a ventriculoperitoneal shunt, performed subtemporal craniectomies, and instructed our patient to apply different sized headbands to allow her to anticipate and control her own intracranial pressure: a tight headband for low-pressure headaches; no band for high-pressure headaches. Magnetic resonance imaging and intracranial pressure monitoring revealed this was not a placebo effect.

Acute disc herniation in the elderly

BACKGROUND

Acute disc prolapse in young adults has been studied extensively. However, little is known about acute disc prolapse in the elderly.

OBJECTIVE

We aimed to define the features of acute disc prolapse in the elderly.

DESIGN, SETTING AND PATIENTS

Elderly (≥ 65 years) patients who had lumbar or thoracic discectomy for acute (< 3 months) disc prolapse in our unit between July 2004 and March 2010 were identified. For comparison, we used a 'young' (25-45 years) patient cohort with acute thoracic or lumbar disc prolapse. Data collected included age, symptom onset, preoperative signs and spinal level.

RESULTS

During the study period, 390 patients had discectomy, of which 59.7% were 'young' and 7.4% 'elderly'. The young and elderly patients had significantly different distributions of prolapsed disc levels. In the young, 97% of all disc protrusions were at L4/5 or L5/S1, but < 50% were at these levels in the elderly. In the elderly, about 10% of disc protrusions were thoracic.

CONCLUSIONS

Acute disc prolapse is rare in the elderly and primarily affects the upper lumbar and lower thoracic spine.

Variability in the treatment of acute spinal cord injury in the United Kingdom: results of a national survey

The aim of this study was to examine how traumatic spinal cord injury is managed in the United Kingdom via a questionnaire survey of all neurosurgical units. We contacted consultant neurosurgeons and neuroanesthetists in all neurosurgical centers that manage patients with acute spinal cord injury. Two clinical scenarios-of complete and incomplete cervical spinal cord injuries-were given to determine local treatment policies. There were 175 responders from the 33 centers (36% response rate). We ascertained neurosurgical views on urgency of transfer, timing of surgery, nature and aim of surgery, as well as neuroanesthetic views on type of anesthetic, essential intraoperative monitoring, drug treatment, and intensive care management. Approximately 70% of neurosurgeons will admit patients with incomplete spinal cord injury immediately, but only 40% will admit patients with complete spinal cord injury immediately. There is no consensus on the timing or even the role of surgery for incomplete or complete injuries. Most (96%) neuroanesthetists avoid anesthetics known to elevate intracranial pressure. What was deemed essential intraoperative monitoring, however, varied widely. Many (22%) neuroanesthetists do not routinely measure arterial blood pressure invasively, central venous pressure (85%), or cardiac output (94%) during surgery. There is no consensus among neuroanesthetists on the optimal levels of arterial blood pressure, or oxygen and carbon dioxide partial arterial pressure. We report wide variability among U.K. neurosurgeons and neuroanesthetists in their treatment of acute traumatic spinal cord injury. Our findings reflect the lack of Class 1 evidence that early surgical decompression and intensive medical management of patients with spinal cord injury improves neurological outcome.