✓ A patient presenting with progressive paraparesis was found to have a dural sacral arteriovenous (AV) fistula. His condition deteriorated abruptly after thoracolumbar angiography. Embolization of the fistula improved the patient's status so that he was able to walk with crutches. One year later his neurological condition worsened. He was treated via an enlarged laminectomy because of uncertainty concerning a lipoma noted on the initial computerized tomography scan. The lesion consisted of an intradural filum terminale lipoma associated with an AV fistula, both of which were excised. The patient's condition was unchanged 6 months later. The different types of spinal lipomas and spinal AV malformations are reviewed, and mechanisms are proposed to explain the clinical deterioration in this patient. Venous hypertension seems to be the most likely possibility. The lipoma may have produced local hypervascularization of the dura mater with a subsequently acquired AV fistula.
Michel Djindjian, Patrick Ayache, Pierre Brugieres and Jacques Poirier
Philippe Decq, Caroline Le Guérinel, Jean-Christophe Sol, Pierre Brugières, Michel Djindjian and Jean-Paul Nguyen
Object. Hydrocephalus associated with Chiari I malformation is a rare entity related to an obstruction in the flow of cerebrospinal fluid (CSF) in the foramen of Magendie. Like all forms of noncommunicating hydrocephalus, it can be treated by endoscopic third ventriculostomy (ETV). The object of this study is to report a series of five cases of hydrocephalus associated with Chiari I malformation and to evaluate the use of ETV in the treatment of this anomaly.
Methods. Five patients (four women and one man with a mean age of 29.6 years) underwent ETV for hydrocephalus associated with Chiari I malformation between April 1991 and February 1997. All patients had presented with paroxysmal headaches, which in two cases were associated with visual disorders. All patients had also presented with hydrocephalus (mean transverse diameter of the third ventricle 12.79 mm; mean sagittal diameter of the fourth ventricle 18.27 mm) with a mean herniation of the cerebellar tonsils at 13.75 mm below the basion—opisthion line. Surgery was performed in all patients by using a rigid endoscope. No complications occurred either during or after the procedure, except in one patient who experienced a wound infection that was treated by antibiotic medications.
The mean duration of follow up in this study was 50.39 months. Four patients became completely asymptomatic and remained stable throughout the follow-up period. One patient required an additional third ventriculostomy after 1 year, due to secondary closure, and has remained stable since that time. Postoperative magnetic resonance images demonstrated a significant reduction in the extent of hydrocephalus in all patients (mean transverse diameter of the third ventricle 6.9 mm [p = 0.0035]; mean sagittal diameter of the fourth ventricle 10.32 mm [p = 0.007]), with a mean ascent of the cerebellar tonsils from 13.75 mm below the basion—opisthion line to 7.76 mm below it (p = 0.01). In addition, CSF flow was identified on either side of the orifice of the third ventriculostomy in all patients postoperatively.
Conclusions. Results in this series confirm the efficacy of ETV in the treatment of hydrocephalus associated with Chiari I malformation. It is a reliable, minimally invasive technique that also provides a better understanding of the pathophysiology of this malformation.
Report of three cases
Carine Karachi, Caroline Le Guérinel, Pierre Brugières, Eliane Melon and Philippe Decq
✓ Idiopathic stenosis of the foramina of Magendie and Luschka is a rare cause of obstructive hydrocephalus involving the four ventricles. Like other causes of noncommunicating hydrocephalus, it can be treated with endoscopic third ventriculostomy (ETV).
Three patients who were 21, 53, and 68 years of age presented with either headaches (isolated or associated with raised intracranial pressure) or vertigo, or a combination of gait disorders, sphincter disorders, and disorders of higher functions. In each case, magnetic resonance (MR) imaging demonstrated hydrocephalus involving the four ventricles (mean transverse diameter of third ventricle 14.15 mm; mean sagittal diameter of fourth ventricle 23.13 mm; and mean ventricular volume 123.92 ml) with no signs of a Chiari Type I malformation (normal posterior fossa dimensions, no herniation of cerebellar tonsils). The diagnosis of obstruction was confirmed using ventriculography (in two patients) and/or MR flow images (in two patients). All patients presented with marked dilation of the foramen of Luschka that herniated into the cisterna pontis. All patients were treated using ETV.
No complications were observed. All three patients became asymptomatic during the weeks following the surgical procedure and remained stable at a mean follow-up interval of 36 months. Postoperative MR images demonstrated regression of the hydrocephalus (mean transverse diameter of third ventricle 7.01 mm; mean sagittal diameter of fourth ventricle 16.6 mm; and mean ventricular volume 79.95 ml), resolution of dilation of the foramen of Luschka, and good patency of the ventriculostomy (flow sequences).
These results confirm the existence of hydrocephalus caused by idiopathic fourth ventricle outflow obstruction without an associated Chiari Type I malformation, and the efficacy of ETV for this rare indication.
Raphaël Blanc, Hassan Hosseini, Caroline Le Guerinel, Pierre Brugières and André Gaston
✓ Acute ischemic infarction of the posterolateral bulbomedullary junction occurred in a 28-year-old man who underwent arterial embolization for the treatment of an intracranial dural arteriovenous malformation. The migration of the embolic agent in the posterior spinal artery via a peripheral anastomosis between the middle meningeal artery and the posterior meningeal artery was responsible for this complication. The cast of glue in the radiculopial system at the upper cervical level was visible on computed tomography scanning, and magnetic resonance imaging demonstrated circumscribed signal changes and restricted diffusion in the arterial territory of the bulbomedullary junction. The authors discuss the anatomical, clinical, and technical issues of this rare complication.
Philippe Decq, Pierre Brugières, Caroline Le Guerinel, Michel Djindjian, Yves Kéravel and Jean-Paul Nguyen
✓ The use of an endoscope in the treatment of suprasellar arachnoid cysts provides an opening of the upper and lower cyst walls, thereby allowing the surgeon to perform a ventriculocystostomy (VC) or a ventriculocystocysternostomy (VCC). To discover which procedure is appropriate, magnetic resonance (MR)—imaged cerebrospinal fluid (CSF) flow dynamics in two patients were analyzed, one having undergone a VC and the other a VCC using a rigid endoscope. Magnetic resonance imaging studies were performed before and after treatment, with long-term follow-up periods (18 months and 2 years). The two patients were reoperated on during the follow-up period because of slight headache recurrence in one case and MR—imaged CSF flow dynamics modifications in the other. In each case surgery confirmed the CSF flow dynamics modifications appearing on MR imaging.
In both cases, long-term MR imaging follow-up studies showed a secondary closing of the upper wall orifice. After VCC, however, the lower communication between the cyst and the cisterns remained functional.
The secondary closure of the upper orifice may be explained as follows: when opened, the upper wall becomes unnecessary and tends to return to a normal shape, leading to a secondary closure. The patent sylvian aqueduct aids this phenomenon, as observed after ventriculostomy when the aqueduct is secondarily functional.
The simplicity of the VCC performed using endoscopic control, which is the only procedure to allow the opening in the cyst's lower wall to remain patent, leads the authors to advocate this technique in the treatment of suprasellar arachnoid cysts.
Frederic Ricolfi, Philippe Decq, Pierre Brugieres, Jerry Blustajn, Eliane Melon and Andre Gaston
✓ A case involving the absence of the midthird portion of the basilar artery (BA) associated with a ruptured fusiform aneurysm of the superior third of the basilar artery discovered after a subarachnoid hemorrhage is reported. Surgical clipping was precluded by the anatomical conditions. The aneurysm was treated by occlusion (surgical clipping and balloon occlusion) of both posterior communicating arteries to decrease the hemodynamic stress on the aneurysm wall. The pericerebellar arterial network was allowed to supply the distal BA and its collateral vessels indirectly. This treatment proved to be efficient; angiography and magnetic resonance imaging demonstrated shrinkage of the aneurysm cavity. The absence of the midthird of the BA is usually associated with a persisting trigeminal artery (nonexistent in this case) or disclosed in cases of acute BA occlusion in dramatic clinical conditions. A similar anatomical feature has been described only once before. There may be a segmental maldevelopment of the longitudinal neural arteries during embryogenesis or a defect in fusion of these paired structures during the development of the BA itself.
Michel Djindjian, Patrick Ayache, Pierre Brugières, Denis Malapert, Marielle Baudrimont and Jacques Poirier
✓ The clinical and pathological features of a giant cauda equina paraganglioma arising from the intradural filum terminale is described. Scattered mature large neurons characterized the tumor as a gangliocytic paraganglioma. Histologically, these neoplasms have considerable similarity with ependymoma and the diagnosis can be easily missed unless special techniques are employed.
Béchir Jarraya, Pierre Brugières, Naoki Tani, Jérôme Hodel, Bénédicte Grandjacques, Gilles Fénelon, Philippe Decq and Stéphane Palfi
The authors describe the case of a 35-year-old woman with a history of an addiction to cigarette smoking who presented with an intracerebral hemorrhage from a ruptured arteriovenous malformation. The patient reported an immediate and complete disruption of her addiction to cigarette smoking following her stroke. Structural MR imaging revealed a lesion of the posterior cingulate cortex. Neuropsychological tests showed intact cognitive functioning. This observation suggests that the posterior cingulate cortex may play a role in the addiction to cigarette smoking.
Suhan Senova, Koichi Hosomi, Jean-Marc Gurruchaga, Gaëtane Gouello, Naoufel Ouerchefani, Yara Beaugendre, Hélène Lepetit, Jean-Pascal Lefaucheur, Romina Aron Badin, Julien Dauguet, Caroline Jan, Philippe Hantraye, Pierre Brugières and Stéphane Palfi
Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is a well-established therapy for motor symptoms in patients with pharmacoresistant Parkinson's disease (PD). However, the procedure, which requires multimodal perioperative exploration such as imaging, electrophysiology, or clinical examination during macrostimulation to secure lead positioning, remains challenging because the STN cannot be reliably visualized using the gold standard, T2-weighted imaging (T2WI) at 1.5 T. Thus, there is a need to improve imaging tools to better visualize the STN, optimize DBS lead implantation, and enlarge DBS diffusion.
Gradient-echo sequences such as those used in T2WI suffer from higher distortions at higher magnetic fields than spin-echo sequences. First, a spin-echo 3D SPACE (sampling perfection with application-optimized contrasts using different flip angle evolutions) FLAIR sequence at 3 T was designed, validated histologically in 2 nonhuman primates, and applied to 10 patients with PD; their data were clinically compared in a double-blind manner with those of a control group of 10 other patients with PD in whom STN targeting was performed using T2WI.
Overlap between the nonhuman primate STNs segmented on 3D-histological and on 3D-SPACE-FLAIR volumes was high for the 3 most anterior quarters (mean [± SD] Dice scores 0.73 ± 0.11, 0.74 ± 0.06, and 0.60 ± 0.09). STN limits determined by the 3D-SPACE-FLAIR sequence were more consistent with electrophysiological edges than those determined by T2WI (0.9 vs 1.4 mm, respectively). The imaging contrast of the STN on the 3D-SPACE-FLAIR sequence was 4 times higher (p < 0.05). Improvement in the Unified Parkinson's Disease Rating Scale Part III score (off medication, on stimulation) 12 months after the operation was higher for patients who underwent 3D-SPACE-FLAIR–guided implantation than for those in whom T2WI was used (62.2% vs 43.6%, respectively; p < 0.05). The total electrical energy delivered decreased by 36.3% with the 3D-SPACE-FLAIR sequence (p < 0.05).
3D-SPACE-FLAIR sequences at 3 T improved STN lead placement under stereotactic conditions, improved the clinical outcome of patients with PD, and increased the benefit/risk ratio of STN-DBS surgery.