Dorothy Lang

ANTEROGRADE BUT NOT RETROGRADE MEMORY LOSS FOLLOWING COMBINED MAMMILLARY BODY AND MEDIAL THALAMIC LESIONS

We report the first human case of combined mammillary body and medial thalamic lesions due to focal pathology. A patient presented with a multi-lobular lesion that affected the mammillary bodies, the medial thalamus and the brain stem. On neuropsychological testing, he showed significant anterograde memory impairment, with marked impairment on delayed story recall, but normal or only mildly impaired performance on retrograde memory tasks. Our findings corroborate the results of recent non-human lesion studies and indicate that some of the well-established features of the amnesic syndrome, such as severe retrograde amnesia, may not be due to primary diencephalic pathology. Significant retrograde amnesia may result from cortical pathology or from an interaction between cortical and subcortical pathology.

The suboccipital transcondylar approach to the clivus and cranio-cervical junction for ventrally placed pathology at and above the foramen magnum

SummaryThe dorsolateral suboccipital transcondylar approach for pathology anterolateral or ventral to the neuraxis around the lower clivus and brainstem was used in 10 patients with a variety of different pathological problems. Key features of the approach include exposure and mobilisation of the vertebral artery and resection of the postero-medial portion of the atlanto-occipital joint. Despite the excellent access achieved additional exposure may be required in some patients with strictly anterior pathology or a lesion above the mid-clivus.

Mammillary Body Damage Results in Memory Impairment But Not Amnesia

Abstract Isolated mammillary body pathology is rare, and there remains controversy as to whether such focal lesions will result in amnesia. We report two cases of lesions to the mammillary bodies arising from a suprasellar tumour. Neither case underwent radical surgical or radiotherapy treatment, which in themselves might have affected memory functioning. In both patients, extensive memory testing across a wide range of memory tasks showed relatively limited anterograde memory impairment which was mainly evident on some but not all delayed recall tasks. Neither patient showed evidence of significant retrograde amnesia. Our negative findings contrast with recent case reports, and these conflicting observations are discussed in terms of the possible role of coexistent cerebral pathology that may exacerbate the effects of mammillary body lesions to produce amnesic levels of performance. Our data point to a limited/selective role for the mammillary bodies in human memory, and raise the possibility that recove...

Craniofacial Access in Children

Summary We have used craniofacial access in 20 children (age range 3/12–14 years) for complex skull base/intracranial pathology over the past 5 years. The majority of the patients had a tumour – 7 of the skull base, 5 extensive suprasellar lesions and 3 acoustic neuromas; 4 had an aneurysm or AVM and in 1 there was a congenital problem.This extended application of established adult techniques in a paediatric practice emphasises the fundamental point that the quintessence of good surgical practice is the construction of an operation for the individual patients pathology. We therefore used transzygomatic, orbital, transoral, transmandibular, petrous, transcondylar, translabyrinthine and transbasal access techniques. Good function and cosmesis with minimal complications were achieved. We have not observed complications with craniofacial growth and the majority of patients were able to return to normal school. The range of approaches used emphasise the importance of a multidisciplinary team with both paediatric and neurosurgical expertise, especially with complex vascular and skull base pathology, in dealing with these difficult problems. The case for specialist referral merits some discussion within the representative bodies of paediatric neurosurgeons.

The transzygomatic approach: an anatomical study

The transzygomatic approach has been utilised to facilitate neurosurgical access to the skull base for a number of years. Advocates of the technique claim the additional access gained provides wider exposure of the neurosurgical pathology and improved visualisation of adjacent vital neurovascular structures. The aim of this study was to photographically demonstrate the technique and to highlight the anatomical areas to which access can be improved. A morphological cadaver study was undertaken. Specific intracranial structures in the vicinity of the skull base were targeted and exposure was compared with and without the zygoma in position. This study demonstrates the increase in exposure of the basilar bifurcation (via a transsylvian approach) and the P2 segment of the posterior cerebral artery (via a subtemporal approach) that can be achieved and the improved access to adjacent anatomical compartments. It can be concluded that the transzygomatic approach is a relatively simple technique which can readily increase exposure of the skull base. It also provides simultaneous access to the superior pole of the infratemporal fossa, the pterygopalatine fossa and the orbit.

The Extended Transbasal Approach: A Quantitative Anatomical and Histological Study

Summary Since its introduction in 1972 the transbasal approach to the anterior fossa and sphenoethmoidal region has undergone a number of modifications. The extended transbasal approach with preservation of olfaction not only improves exposure of the anterior fossa, but also provides access to the clivus as far inferiorly as the foramen magnum. An anatomical study has been undertaken to photographically demonstrate and quantify the varying degrees of exposure that this technique provides. The pituitary stalk was used as an intracranial target. The amount of exposure was compared using a standard subfrontal approach, a transbasal approach and an extended transbasal with preservation of olfaction. In addition, a histological study was carried out to investigate the level to which identifiable olfactory nerves extended into the nasal mucosa. The anatomical study demonstrates the area of the “external window of exposure” can be doubled using a transbasal approach and more than quadrupled using the extended transbasal approach, when gaining access to the pituitary stalk. In addition, the study highlights the exposure of other anatomical areas, such as the medial orbit, the cavernous sinus, the clivus and the vertebrobasilar complex. The histological study establishes that the olfactory nerves extend only 10mms below the cribriform plate.

The extended transbasal approach: clinical applications and complications.

Summary Objectives. To describe in detail key technical aspects of the extended transbasal approach which involves en-bloc mobilisation of the supraorbital rim, the orbital roof and the nasoethmoidal complex. In some patients osteotomies were performed around the cribriform plate with a view to maintaining olfaction. To review 18 patients with deep seated lesions located in the central skull base region (including 6 recurrences) to highlight patient selection, presentation, surgical morbidity and outcome. Methods. Prospective data recording and clinical chart review. Results. Outcome was assessed at a minimum of 1 year after operation using the Glasgow Outcome Score. Thirteen patients had made a good recovery, 1 was moderately disabled, 2 were severely disabled (both had been severely disabled before operation), and 2 died. By contrast, quality of life assessment indicated that only 7 of the surviving 14 adults had returned to normal levels of activity and perceived health; although 6 of the other 7 patients had resumed their former occupations, their follow up assessments showed a reduced quality of life. Of the 13 patients who had an olfaction preservation procedure, 6 showed appreciation of smell on formal testing. Conclusions. In patients with progressive and extensive deep seated lesions this technique provides wide exposure in a shallow surgical field. Complication rates although acceptable were significantly higher in patients with intradural lesions. In some selected patients it was possible to preserve olfaction. Specific surgical outcome assessments pointed to satisfactory results, but failed to reflect the degree of patient disability. There is a need for outcome measures that take into account the patients expectations and which address his quality of life in order to validate the benefits of these procedures.

The transzygomatic approach: A long-term clinical review

SummaryThe transzygomatic approach has been utilised to improve access to the skull base, infratemporal fossa and orbit for a number of years. It provides a low anterolateral approach to the skull base, along the floor of the middle fossa. It allows both a transsylvian and subtemporal approach with a reduction in brain retraction and better exposure of adjacent neurovasculature structures. A long term review of 53 patients is presented highlighting outcome at two years post surgery and morbidity of the approach. It is concluded that the technique is versatile and can be used to improve exposure of a variety of anatomical locations. There is minimal long term morbidity attributable to the surgery of access and the majority of patients have had good outcomes.

A Randomized Controlled Trial of Prophylactic Intra-aortic Balloon Counterpulsation in High-Risk Aneurysmal Subarachnoid Hemorrhage

Background and Purpose— To assess whether prophylactic postoperative intraaortic balloon counterpulsation (IABC) reduces the risk of poor outcome because of vasospasm following aneurysmal subarachnoid haemorrhage relative to conventional hypervolemic therapy (HT). Methods— This was a single-center, parallel group randomized controlled trial. Patients suffering a subarachnoid hemorrhage at high risk of vasospasm were eligible. Patients were randomly allocated to receive prophylactic IABC (n=35) or HT (n=36). The primary end point was Glasgow Outcome and SF-36 scores assessed at 6 months by a blinded and independent observer and analyzed by intention to treat. Secondary analysis of physiological parameters was by treatment performed. Results— Twenty-seven patients in each arm had a good outcome (P=0.55). There was no statistical difference in mean SF-36 score (t=0.39, P=0.70). There were no long-term complications secondary to IABC. There were no differences in preload (pulmonary artery wedge pressure, P=0.97) or afterload (mean arterial pressure, P=0.97). IABC was associated with a lower cardiac output (P=0.002) and higher systemic vascular resistance (P=0.005), although for both groups mean cardiac output was >6 L/min. Cerebral blood flow was not different between groups: HT=41.5 (SD 7.2), IABP=44.9 (SD 8.6) mL/100 g/min (P=0.14). Conclusions— In this study, prophylactic IABC did not improve perfusion indices or confer any clinical benefit following subarachnoid haemorrhage in patients with normal cardiac function. The study was small, however, and cannot be extrapolated to patients with cardiac failure and medically refractory symptomatic cerebral vasospasm. Clinical Trial Registration— This trial was not registered because enrolment began prior to July 1, 2005.

Fibrin Sealant Injection: An Aid to Reduce Venous Bleeding during Jugular Bulb and Sigmoid Sinus Dissection in Glomus Jugulare (Jugulotympanic Paraganglioma) Surgery.

Glomus jugulare (jugulotympanic paraganglioma) surgery requires tumor dissection in the region of the jugular bulb, upper internal jugular vein, and sigmoid sinus. Despite ligation or external compression of the sigmoid sinus proximally and ligation of the internal jugular vein distally, troublesome venous bleeding can arise from the inferior petrosal sinus or condylar veins at the medial wall of the jugular bulb. Excessive packing in this area can place the integrity of the lower cranial nerves at risk. We report a technique in which Tisseel(®) fibrin sealant is injected into the ligated sigmoid sinus and internal jugular vein. This forms an internal cast around the tumor in the sigmoid-jugular complex and helps seal the inferior petrosal sinus and condylar veins. This allows for safer dissection with reduced venous bleeding. Our experience in five cases has shown this technique to be effective.