Radiologic and Neurosurgical Diagnosis of Arterial Neurovascular Conflict on Magnetic Resonance Imaging for Trigeminal Neuralgia in Routine Clinical Practice.

OBJECTIVE: The most common cause of trigeminal neuralgia is neurovascular conflict, particularly arterial compression of the trigeminal nerve (ACTN). It is possible to show this condition preoperatively on fine-cut constructive interference in steady state magnetic resonance imaging (MRI), supplemented by time-of-flight magnetic resonance angiography. We have noticed significant variability in the interpretation of these studies between radiologists and the treating neurosurgeon. We have assessed the sensitivity and specificity of these 2 styles of interpretation compared with the intraoperative observations. METHODS: We studied 68 patients who underwent de novo microvascular decompression from 2011 to 2018 under the care of a single neurosurgeon in Melbourne, Australia. Data was recorded prospectively in the radiology reports, operation reports, hospital admission records and neurosurgeon correspondence from the perioperative clinic reviews. In particular, the surgical interpretation of the MRI was clearly described prospectively and preoperatively in the correspondence. The presence or absence of ACTN was recorded prospectively in the operation report. These data were collated retrospectively by the first author. RESULTS: Of patients, 83.8% (57/68) had clear ACTN confirmed at surgery. Radiologists detected this abnormality in 50.9% (29/57) of these patients, with a sensitivity of 50.9% and specificity of 81.8%. The operating neurosurgeon detected ACTN in 87.7% (50/57) of the positive cases with a sensitivity of 87.7% and a specificity of 72.7%. Statistical analysis showed a significant disagreement between both styles of interpretation, with a radiologic accuracy of 55.9% compared with 85.3% neurosurgically (P < 0.0001). Follow-up review of the patient's response to surgery further supported the neurosurgical diagnosis of ACTN. CONCLUSIONS: There was a strong tendency for radiologists to underreport ACTN on the preoperative MRI compared with the intraoperative findings. In this series, the neurosurgeon was able to accurately detect ACTN in 88% of patients preoperatively. However, the diagnosis of absent ACTN was still associated with a false-negative rate of 46.7% when the neurosurgeon performed the interpretation. At the current standard of fine-cut constructive interference in steady state MRI in Melbourne, underdetection of ACTN remains common. Clinicians using this test need to be acutely aware of its limitations in deciding whether to proceed to microvascular decompression.

Intravenous milrinone for treatment of delayed cerebral ischaemia following subarachnoid haemorrhage: a pooled systematic review.

Small trials have demonstrated promising results utilising intravenous milrinone for the treatment of delayed cerebral ischaemia (DCI) after subarachnoid haemorrhage (SAH). Here we summarise and contextualise the literature and discuss the future directions of intravenous milrinone for DCI. A systematic, pooled analysis of literature was performed in accordance with the PRISMA statement. Methodological rigour was analysed using the MINORS criteria. Extracted data included patient population; treatment protocol; and clinical, radiological, and functional outcome. The primary outcome was clinical resolution of DCI. Eight hundred eighteen patients from 10 single-centre, observational studies were identified. Half (n = 5) of the studies were prospective and all were at high risk of bias. Mean age was 52 years, and females (69%) outnumbered males. There was a similar proportion of low-grade (WFNS 1-2) (49.7%) and high-grade (WFNS 3-5) (50.3%) SAH. Intravenous milrinone was administered to 523/818 (63.9%) participants. Clinical resolution of DCI was achieved in 375/424 (88%), with similar rates demonstrated with intravenous (291/330, 88%) and combined intra-arterial-intravenous (84/94, 89%) therapy. Angiographic response was seen in 165/234 (71%) receiving intravenous milrinone. Hypotension (70/303, 23%) and hypokalaemia (31/287, 11%) were common drug effects. Four cases (0.5%) of drug intolerance occurred. Good functional outcome was achieved in 271/364 (74%) patients. Cerebral infarction attributable to DCI occurred in 47/250 (19%), with lower rates in asymptomatic spasm. Intravenous milrinone is a safe and feasible therapy for DCI. A signal for efficacy is demonstrated in small, low-quality trials. Future research should endeavour to establish the optimal protocol and dose, prior to a phase-3 study.

Hyponatraemia and hypernatraemia: Disorders of Water Balance in Neurosurgery.

Disorders of tonicity, hyponatraemia and hypernatraemia, are common in neurosurgical patients. Tonicity is sensed by the circumventricular organs while the volume state is sensed by the kidney and peripheral baroreceptors; these two signals are integrated in the hypothalamus. Volume is maintained through the renin-angiotensin-aldosterone axis, while tonicity is defended by arginine vasopressin (antidiuretic hormone) and the thirst response. Edelman found that plasma sodium is dependent on the exchangeable sodium, potassium and free-water in the body. Thus, changes in tonicity must be due to disproportionate flux of these species in and out of the body. Sodium concentration may be measured by flame photometry and indirect, or direct, ion-sensitive electrodes. Only the latter method is not affected by changes in plasma composition. Classification of hyponatraemia by the volume state is imprecise. We compare the tonicity of the urine, given by the sodium potassium sum, to that of the plasma to determine the renal response to the dysnatraemia. We may then assess the activity of the renin-angiotensin-aldosterone axis using urinary sodium and fractional excretion of sodium, urate or urea. Together, with clinical context, these help us determine the aetiology of the dysnatraemia. Symptomatic individuals and those with intracranial catastrophes require prompt treatment and vigilant monitoring. Otherwise, in the absence of hypovolaemia, free-water restriction and correction of any reversible causes should be the mainstay of treatment for hyponatraemia. Hypernatraemia should be corrected with free-water, and concurrent disorders of volume should be addressed. Monitoring for overcorrection of hyponatraemia is necessary to avoid osmotic demyelination.

Tension Pneumocephalus from Positive Pressure Ventilation Following Endoscopic Skull Base Surgery: Case Series and an Institutional Protocol for the Management of Postoperative Respiratory Distress.

BACKGROUND: Tension pneumocephalus (TP) is a rare but feared complication of endoscopic endonasal skull base surgery. In contrast to simple pneumocephalus, which is common after endoscopic transnasal approaches and managed conservatively, TP represents a neurosurgical emergency and mandates urgent decompression. CASE DESCRIPTION: Here we present 2 cases of TP as a consequence of positive pressure ventilation following endoscopic endonasal skull base surgery. Both occurred during resuscitation for postoperative hypoxia. These cases prompted the development of an institution-wide protocol to identify and manage patients at risk of TP after extended skull base approaches. CONCLUSIONS: To our knowledge, these are the only such cases of postoperative TP following positive pressure ventilation in the literature.

Long-term follow-up for keystone design perforator island flap for closure of myelomeningocele.

PURPOSE: We have previously reported a small series on the closure of large myelomeningocele (MMC) defects with a keystone design perforator island flap (KDPIF) in a paediatric neurosurgical centre in Australia. We are now presenting an updated longer term follow-up of an expanded series demonstrating longer term durability of this vascularized flap for large myelomeningocele defects. METHODS: The prospective data from the Monash Neurosurgical Database were used to select all cases of MMC between December 2008 and September 2016. Retrospective analysis of the neurosurgical database revealed an additional three patients who underwent KDPIF closure at the Monash Medical Centre for MMC repair at birth. RESULTS: Wound healing was satisfactory in all six cases. With delayed follow-up, there was no associated skin flap separation, skin flap dehiscence, skin flap necrosis, cerebro-spinal fluid leak, however two infections were encountered, both resolved with conservative management including antibiotics and simple washout. CONCLUSION: In this expanded case series with increased longevity of follow-up, the keystone design perforator island flap remains a robust alternative for closure of large myelomeningocele defects.

Subdural haematoma following infant spinal anaesthesia.

INTRODUCTION: Subdural haematoma (SDH) is rare following spinal anaesthesia and has not been reported previously in an infant. Non-accidental injury is the commonest cause of subdural haematoma in infants. METHODS: We describe two cases of SDH following spinal anaesthesia in infants. RESULTS: In both cases, forensic investigation was commenced and no evidence of child abuse was found. Both children are well 2 years after diagnosis. CONCLUSION: Paediatric health workers should be aware of the possibility of SDH after spinal anaesthesia and consider this as a differential diagnosis when investigating possible non-accidental injury in an infant.

Keystone design perforator island flap for closure of myelomeningocele.

OBJECT: We present a series of three infants who underwent keystone design perforator island flap (KDPIF) closure for myelomeningocele in a paediatric neurosurgical centre in Australia. This is the first recorded utilization of this flap for primary closure of myelomeningocele (MMC). METHODS: The prospective data from the Monash Neurosurgical Database were used to select all cases of MMC between December 2008 and September 2010. Retrospective analysis of these cases revealed three patients who underwent KDPIF at Monash Medical Centre for MMC repair at birth. RESULTS: Wound healing was prompt and satisfactory in all three cases. No minor or major complications were noted. In particular, there was no associated skin flap separation, skin flap dehiscence, skin flap necrosis, infection, cerebrospinal fluid leak, or need for return to theatre for further intervention to the wound. This keystone design perforator island flap is based on random perforating musculo/fasciocutaneous perforators. In our experience, this robust flap provides better tissue bulk, more reliable vascularity and a wider geometrical versatility than traditional random 1:1 cutaneous flaps. CONCLUSION: Whilst primary closure remains an option for myelomeningocele closure, primary repair of larger defects can lead to closure site tension, stretching of inelastic scar tissue and inadequate soft tissue cover. In this small series, we have demonstrated the use of keystone design perforator island flap closure as an alternative for larger and more complex lesions.

Bilateral open thoracic cordotomy for refractory cancer pain: a neglected technique?

At least 10% of patients with cancer have pain that is refractory to systemic analgesics. For most of these patients, interventional techniques may be of benefit but are often not considered or are difficult to access. Of these techniques, spinal analgesia is most commonly used in Australia and the United Kingdom, and neurosurgical procedures, such as open cordotomy with sectioning of the spinothalamic tract, are rarely used. We describe a case illustrating the successful use of bilateral open thoracic cordotomy in a patient with refractory mixed nociceptive and neuropathic pain secondary to a lumbosacral tumor. We discuss the various interventional options and review the recent literature regarding the use of both percutaneous and open cordotomy for cancer pain.

Neurocysticercosis causing sudden death.

Neurocysticercosis causes significant morbidity due to neurologic manifestations including seizures. Sudden unexpected death in epilepsy (SUDEP) is responsible for mortality associated with seizure disorders. This case highlights death from neurocysticercosis and possible SUDEP in a nonendemic country.

Wound healing after craniotomy: a randomized trial comparing scalp clips to artery forceps for scalp hemostasis.

OBJECT: In this prospective randomized clinical trial, investigators looked at wound healing after craniotomy. The hypothesis was that the self-closing plastic scalp clips used for hemostasis on the skin edge might lead to localized microscopic tissue damage and subsequent delayed wound healing. METHODS: The trial consisted of 2 arms in which different methods were used to secure scalp hemostasis: 1) the routinely used plastic clips (Scalpfix, Aesculap); and 2) the older method of artery forceps placed on the galea. Participants were restricted to those > 16 years of age undergoing craniotomies expected to last > 2 hours. Repeat operations were not included. One hundred fifty patients were enrolled. They were visited at 3 and 6 weeks postoperatively by an observer blinded to the method used, and the wounds were assessed for macroscopic epithelial closure, signs of infection, and hair regrowth by using a predefined assessment scale. RESULTS: The results showed no significant difference in wound healing between the 2 groups at either 3 weeks (OR 0.55, 95% CI 0.27-1.11; p = 0.09) or 6 weeks (OR 0.79, 95% CI 0.39-1.58; p = 0.50). The length of operation was found to be a significant factor affecting wound healing at 6 weeks (OR/hour 0.68, 95% CI 0.51-0.92; p = 0.01). CONCLUSIONS: The use of Aesculap Scalpfix self-retaining plastic scalp clips on the skin edge during craniotomy surgery does not appear to affect wound healing significantly to the postoperative 6-week mark.

Reduction in shunt infection using antibiotic impregnated CSF shunt catheters: an Australian prospective study.

Antibiotic impregnated shunt catheters have emerged as a promising tool against the continuing challenge of shunt infection. We present our prospective evaluation of the efficacy of antibiotic (rifampicin and clindamycin) impregnated cerebrospinal fluid (CSF) shunt catheters (AIC) in a mixed paediatric and adult Australian population. We have prospectively evaluated all the cerebrospinal fluid shunt procedures carried out in our institution over a 3-year period since July 2002, after the introduction of AIC in our practice. Patient demographics, indication for shunt procedure, risk factors for infection, shunt infections and other relevant factors were documented. The data has been compared with similar data collected over the previous 7 years of our experience with non-antibiotic impregnated catheters for CSF shunt procedures. Pearson's chi-square and Fisher's exact tests are used for statistical evaluation. From July 2002 to June 2005, 243 shunt procedures were carried out using AICs in 178 patients. There were three shunt infections (1.2%). Rigorous retrospective evaluation of shunt procedures over the preceding 7 years revealed 36 infections in 551 shunt procedures (6.5%). This reduction in the infection rate was statistically significant (p=0.0015 on Pearson's chi-square test and p=0.000529 on Fisher's exact test). We also report that the introduction of ceftriaxone prophylaxis during this period was associated with a reduction in Gram-negative shunt infection, but no effect on overall infection rate. We report rifampicin and clindamycin impregnated CSF shunt catheters significantly reduce the rate of shunt infection in Australian clinical practice. This data and the literature support the routine usage of AIC for all CSF shunt procedures.

Cavernous sinus fistula following percutaneous balloon compression of the trigeminal ganglion. Case report.

In this report the authors describe a patient in whom a symptomatic carotid-cavernous fistula developed 8 months after percutaneous balloon compression of the trigeminal ganglion. The fistula involved a branch of the external carotid artery and was cured with microcatheter embolization.