Background Robot-assisted stereoelectroencephalography (SEEG) may represent a simplified, precise, and safe alternative to the more traditional SEEG techniques. Objective To report our clinical experience with robotic SEEG implantation and to define its utility in the management of patients with medically refractory epilepsy. Methods The prospective observational analyses included all patients with medically refractory focal epilepsy who underwent robot-assisted stereotactic placement of depth electrodes for extraoperative brain monitoring between November 2009 and May 2013. Technical nuances of the robotic implantation technique are presented, as well as an analysis of demographics, time of planning and procedure, seizure outcome, in vivo accuracy, and procedure-related complications. Results One hundred patients underwent 101 robot-assisted SEEG procedures. Their mean age was 33.2 years. In total, 1245 depth electrodes were implanted. On average, 12.5 electrodes were implanted per patient. The time of implantation planning was 30 minutes on average (range, 15-60 minutes). The average operative time was 130 minutes (range, 45-160 minutes). In vivo accuracy (calculated in 500 trajectories) demonstrated a median entry point error of 1.2 mm (interquartile range, 0.78-1.83 mm) and a median target point error of 1.7 mm (interquartile range, 1.20-2.30 mm). Of the group of patients who underwent resective surgery (68 patients), 45 (66.2%) gained seizure freedom status. Mean follow-up was 18 months. The total complication rate was 4%. Conclusion The robotic SEEG technique and method were demonstrated to be safe, accurate, and efficient in anatomically defining the epileptogenic zone and subsequently promoting sustained seizure freedom status in patients with difficult-to-localize seizures.

Technique, Results, and Complications Related to Robot-Assisted Stereoelectroencephalography.

A total of 27 patients with trigeminal schwannoma were treated between 1982 and 1992 at the Neurosurgery Department of Nordstadt Hospital. Twelve cases of solitary schwannoma without any family history or physical stigmata of neurofibromatosis were included and form the basis of this study. There were four women and eight men (mean age 44 years) in this series. Duration of symptoms ranged from 2 months to 6 years. The most frequent symptoms were either pain or numbness of the ipsilateral hemiface. The surgical approach was chosen depending on the tumor type. Tumors that belonged to Type A (five cases), which were predominantly in the middle fossa, were approached using a transsylvian method; Type B (one case), which presented predominantly in the cerebellopontine angle, was operated on via a retrosigmoid suboccipital craniectomy; Type C (five cases), which were dumbbell-shaped extending into both the middle and posterior fossa, were removed via a combined temporal craniotomy-presigmoidal method; and in Type D (one case), in which tumor was primarily extracranial with intracranial extension, an infratemporal extradural approach was undertaken. There was no operative mortality or long-term disability in this series. The follow-up period ranged from 12 to 60 months; during that time magnetic resonance imaging revealed tumor recurrence in two cases after 12 and 48 months, respectively, and these were excised again. An additional 178 cases collected from the world literature are also reviewed and analyzed.

Surgical treatment of trigeminal schwannomas

✓ Over the past 10 years, 2000 patients with facial pain have been evaluated at the Mayfield Neurologic Institute. Sixteen of these patients were found to harbor intracranial tumors. The presenting features of this group of patients are analyzed, and the literature reviewed. Peripherally placed tumors tend to cause atypical facial pain associated with sensory loss. Middle fossa tumors may present as trigeminal neuralgia, but usually cause severe pain of an atypical nature and a progressive neurological deficit. Posterior fossa tumors are most likely to cause trigeminal neuralgia; these neoplasms are usually accompanied by subtle neurological deficits and are readily detected by current diagnostic studies.

Intracranial tumors in patients with facial pain

A consecutive series of 14 patients with trigeminal schwannoma managed surgically at the Neurological Institute of New York since 1970 is reported. Nine women and five men (mean age 40 years) were diagnosed following a mean symptom duration of 33 months. Abnormalities of trigeminal nerve function were present in 11 patients on admission examination. Facial pain was a prominent feature in eight patients. Two patients, both with schwannomas arising from the trigeminal root, presented initially with typical trigeminal neuralgia. Additional cranial nerve palsies or cerebellar or pyramidal tract signs were noted in eight patients. The surgical approach to these tumors depends on their anatomical location. Four patients had tumors confined to the middle fossa, three patients had tumors limited to the posterior fossa, and seven patients had both supratentorial and infratentorial components of their tumors. Twenty operative procedures were performed on these patients, resulting in complete extirpation in six patients, nearly complete removal in seven patients, and partial removal in one patient. Adherence of the tumor to the lateral wall of the cavernous sinus or the brain stem precluded total removal. There was one postoperative death. In the immediate postoperative period, abnormalities of cranial nerves controlling the extraocular muscles were common. In general, these deficits were transient; however, some permanent loss of trigeminal nerve function occurred in nine patients. Two patients required tarsorrhaphy for neurotropic keratitis, and two patients underwent cerebrospinal fluid (CSF) shunting procedures for hydrocephalus or for a persistent CSF leak. The follow-up period ranged from 4 to 177 months (mean 47 months). The clinical features, anatomical considerations, and surgical approach to these rare tumors are discussed. A clinical review of 106 additional cases of trigeminal schwannoma, reported in the English literature since 1935, is also presented.

Trigeminal schwannoma. Surgical series of 14 cases with review of the literature.

Summary: Purpose: Although epilepsy surgery, especially temporal lobe epilepsy surgery, is well established to control seizures in patients remaining on antiepileptic drug (AED) treatment, less information is available about how many seizure-free surgical patients will relapse after discontinuation of AEDs under medical supervision.



Methods: A literature review yielded six retrospective clinical observations.



Results: After planned discontinuation of AEDs in patients rendered seizure free after epilepsy surgery, most often various forms of temporal lobe surgery, the mean percentage recurrence rate in adults in four studies was 33.8%[95% confidence interval (CI), 32.4–35.2%], with maximum follow-up ranging from 1 to 5 years. Seizure recurrence increased during the follow-up of 1 to 3 years and occurred within 3 years of AED discontinuation. In one study of children with temporal lobe epilepsy, the recurrence rate was 20%. More than 90% of adult patients with seizure recurrence regained seizure control with reinstitution of previous AED therapy. Seizure recurrence was unaffected by the duration of postoperative AED treatment; as a consequence, delaying discontinuation beyond 1 to 2 years of complete postoperative seizure control seems to have no added benefit. The occurrence of rare seizures or auras after surgery did not eliminate the possibility of eventual successful AED discontinuation.



Conclusions: AED discontinuation is associated with a seizure recurrence in one in three patients rendered seizure free by epilepsy surgery. These results will be useful in counseling patients about discontinuing AED treatment after successful epilepsy surgery.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.0013-9580.2004.37803.x

Seizure recurrence after planned discontinuation of antiepileptic drugs in seizure-free patients after epilepsy surgery: a review of current clinical experience.

Tumours of the fifth cranial nerve are very rare, comprising only 0.2% of all intracranial neoplasms.

Tumours of the fifth cranial nerve.

Thirty-five patients with partial complex seizures and two patients with generalized epilepsy were treated by stereotactic radiofrequency lesions. Follow-up from 2 to 13 years was available in 30 patients. The stereotactic targets in patients with partial complex seizures were: a) Amygdala; b) Ammon’s horn; c) parahippocampal gyrus; d) Fornix. Depending on scalp EEG and depth electrode studies, each patient had one or more target coagulated, unilaterally or bilaterally. In the 2 cases of generalized epilepsy, bilateral Forel field lesions were performed. Late surgical results are discussed in relation to the depth EEG studies and the number and site of stereotactic lesions.

Late Results of Stereotactic Radiofrequency Lesions in Epilepsy

Surgery of epilepsy: some indications for SEEG.

The concentrations of antiepileptic drugs in histologically normal and pathological brain tissues were investigated in 6 patients submitted to surgery. No significant difference for phenobarbital and phenytoin was found between normal and scar tissue, whereas there was a trend to concentration in tumour tissue (meningioma and glioma) of phenobarbital, phenytoin and carbamazepine. Alteration in the vascular supply and pathological changes at cellular and subcellular levels could be responsible for the differences in the distribution of the drugs. The possible clinical relevance of the preferential concentration of the drugs in tumour tissue is discussed.

Differences between the concentrations of antiepileptic drugs in normal and pathological human brain

Six cases of partial epilepsy operated on for lesions at the temporo-parieto-occipital junction are presented. Three cases had signs of enlargement of one lateral ventricle at the temporo-parieto-occipital carrefour, three had a lateral homonymous hemianopsia and all showed lateralizing interictal EEG abnormalities. The manifold features of the seizures could not be related to the involvement of one or more definite cortical areas.

G. Ettorre

Papers

Tumours of the fifth cranial nerve.

Late Results of Stereotactic Radiofrequency Lesions in Epilepsy

Surgery of epilepsy: some indications for SEEG.

Differences between the concentrations of antiepileptic drugs in normal and pathological human brain

Stereo-EEG and Surgery in Partial Epilepsy with Temporo-Parieto-Occipital Foci