Jack Goodman, Emil Kleinholz and Fremont C. Peck Jr.
Claudia S. Robertson, Richard Foltz, Robert G. Grossman and J. Clay Goodman
✓ The authors have studied the protection against ischemic damage to rabbit spinal cord by pretreatment with agents that block neuronal activity and directly or indirectly reduce tissue metabolism. Hypothermia, thiopental, magnesium, lidocaine, and naloxone were used to pretreat the spinal cord prior to ischemia. Hypothermia and thiopental provided comparable protection: they each increased the duration of ischemia required to produce neurological deficits in 50% of the animals from 26 to 41 minutes. They also increased from 10 to 30 minutes the time that the postsynaptic waves of the spinal somatosensory evoked potential (SSEP) could be absent and the animal still have neurological recovery. Hypothermia and thiopental, when used together, increased the duration of ischemia required to produce neurological deficits to 57 minutes in 50% of the animals. Naloxone increased the duration of ischemia required to produce neurological deficits to 36 minutes in 50% of the animals, and increased to 20 minutes the time that the postsynaptic waves of the SSEP could be absent and the animal still have neurological recovery. Magnesium pretreatment improved neurological outcome, possibly by improving collateral circulation as the SSEP did not fail completely during aortic occlusion in all animals. Lidocaine was not beneficial, perhaps because of the prolonged hypotension that resulted.
Douglas S. Cohen, Geoffrey P. Zubay and Robert R. Goodman
✓ Cavernous malformations that are associated with seizures are often treated by surgical resection consisting of lesion removal, “lesionectomy,” alone. Through retrospective analysis the authors have examined some factors that may predict failure to eradicate seizures by such a procedure. A group of 51 patients were examined who had been treated for supratentorial cavernous malformations with preoperative seizures and received postoperative follow up lasting at least 1 year. There was one mortality in the group. Of the remaining 50 patients, 15 (30%) had continued postoperative seizures despite therapeutic levels of antiepileptic medications. Variables that were significantly associated with continued seizures postoperatively included increasing duration of preoperative seizure history (p = 0.03), increasing number of preoperative seizures (p < 0.003), and female sex (p < 0.04). One hundred percent of patients with only one preoperative seizure or a seizure history lasting less than 2 months were seizure free following lesionectomy: approximately 75% to 80% of all patients with two to five seizures, or a seizure history lasting 2 to 12 months, were seizure free; and only 50% to 55% of those with more than five seizures or with preoperative seizure histories lasting more than 1 year were seizure free postoperatively. This investigation indicates that patients with shorter seizure histories and fewer preoperative seizures can be effectively treated by lesionectomy alone, whereas those with longer histories and more seizures are not effectively treated by this procedure and may require more extensive resections.
John E. Kalsbeck, Alonso L. DeSousa, Martin B. Kleiman, Julius M. Goodman and Edmund A. Franken
✓ Thirteen infants with compartmentalization of the lateral ventricles diagnosed by air encephalography, computerized tomography, or autopsy are reported. In each case, the body of one or both lateral ventricles was completely divided by a membrane posterior to the foramen of Monro. Recognition of this entity is important from both therapeutic and prognostic standpoints.
Richard C. Anderson, Jessica J. Grant, Robert de la Paz, Steven Frucht and Robert R. Goodman
Object. The syndrome of normal-pressure hydrocephalus (NPH) refers to the clinical triad of gait disturbance, dementia, and urinary incontinence in association with idiopathic ventriculomegaly and normal intracranial pressure. Ventriculoperitoneal (VP) shunt placement often yields significant clinical improvements, sometimes without apparent reduction of ventricular size. The authors hypothesized that careful volumetric measurements would show a decrease in ventricular volume in these patients.
Methods. Twenty consecutive patients with NPH underwent placement of VP shunts equipped with programmable valves. In 11 patients pre- and postoperative neuroimaging was performed, which allowed volumetric analysis. Volumetric measurements of the lateral ventricles were calculated in triplicate by National Institutes of Health image-processing software to assess standard computerized tomography (CT) scans (eight patients) or magnetic resonance (MR) images (three patients) obtained before and after shunt placement. Ventricular volumes were also assessed by an independent neuroradiologist. Postoperative studies were performed at a time of clinical improvement, between 1 and 9 months postsurgery (mean 5 months). Preoperative and postoperative Unified Parkinson's Disease Rating Scale evaluations were performed in four patients.
Significant clinical improvement occurred in all patients after shunt placement (mean follow-up period 17.5 months). Although 10 (91%) of 11 patients demonstrated a calculable decrease in volume in the lateral ventricles (mean decrease 39%), formal interpretation of neuroimages indicated a definite decrease in lateral ventricular volume in only three (27%) of 11 patients.
Conclusions. Volumetric measurements obtained to compare preoperative and postoperative CT or MR studies obtained in patients with NPH in whom clinical improvement was seen after shunt placement surgery show a demonstrable decrease in ventricular size. Volumetric measurements may be helpful in clinical assessment postoperatively and in guiding programmable valve pressure settings.
Shearwood McClelland III, Brian Kim, Linda M. Winfield, Blair Ford, Tresha A. Edwards, Seth L. Pullman, Qiping Yu, Guy M. McKhann II and Robert R. Goodman
Deep brain stimulation (DBS) of the subthalamic nucleus (STN) has become a popular treatment for patients with medically refractory Parkinson disease. Many surgeons believe that microelectrode recording (MER) during DBS electrode implantation is needed to optimize placement, whereas stimulation-induced side effects such as paresthesias, dystonic contractions, dyskinesias, and ocular motor signs that become apparent postoperatively may be an indicator of the proximity of the electrode to various boundaries of the STN. This study was performed to evaluate the relationship between mapping of the STN by using MER and postoperative stimulation-induced side effects.
Eighty-two electrodes implanted in 75 patients between March 1999 and March 2003 were retrospectively examined to evaluate the length of the STN defined by MER, and the number of and threshold for postoperative stimulation-induced side effects. Electrodes were typically tested with increasing stimulation amplitudes (maximum 6 V) by using a monopolar array.
The 82 electrodes were associated with 97 stimulation-induced side effects. The mean time between surgery and testing stimulation-induced side effects was 3.9 months. Statistical analysis (two-tailed t-test) revealed no significant difference in the number of stimulation-induced side effects (or the mean threshold for paresthesias, the most common side effect) for electrodes associated with an STN length less than 4.5 mm (13 electrodes) compared with those associated with an STN greater than or equal to 4.5 mm (69 electrodes, p = 0.616). For every electrode, the target adjustment based on MER results was within 2 mm of the image-planned target (usually 1 mm anterior). In the x axis (medial–lateral orientation), there was no systematic difference in adjustments made for the electrodes associated with the shorter compared with the longer STN lengths. In the y axis (anterior–posterior orientation), there was a very small statistically significant difference in the mean adjustment (0.4 mm) between the two groups.
Analysis of these results suggests that a shorter MER-determined STN length alone does not reliably predict the incidence of stimulation-induced side effects.
Shearwood McClelland III, Blair Ford, Patrick B. Senatus, Linda M. Winfield, Yunling E. Du, Seth L. Pullman, Qiping Yu, Steven J. Frucht, Guy M. McKhann II and Robert R. Goodman
Deep brain stimulation (DBS) of the subthalamic nucleus (STN) performed using intraoperative microelectrode recording (MER) to adjust electrode placement has become a widely used treatment for patients with advanced Parkinson disease (PD). Few studies have been conducted to examine the location of implanted electrodes relative to the intended target, and even fewer have been undertaken to investigate the degree to which variations in the location of these electrodes impacts their clinical efficacy. This study was performed to examine these issues.
The authors located 52 bilaterally implanted DBS electrode tips on postoperative magnetic resonance (MR) images obtained in 26 consecutive patients. Postoperative and preoperative planning MR images were merged to determine the DBS electrode tip coordinates relative to the midcommissural point. Surgical records listed the intended target coordinates for each DBS electrode tip. Clinical outcome assessment included the Unified PD Rating Scale (UPDRS) motor score at 1 year, standardized questionnaires, and routine follow-up visits.
The mean difference between electrode tip location and intended target for all 52 electrodes was less than 2 mm in all axes. Only one electrode was farther than 3 mm from the intended target, and this was the only electrode that had to be replaced due to lack of clinical efficacy (lack of tremor suppression); its reimplantation 4 mm more medially provided excellent tremor control. High correlation coefficients indicate that the MR imaging analysis accurately determined the anatomical location of the electrode tips. Blinded videotape reviews of UPDRS motor scores comparing effects of stimulation in patients who were “on” and “off” medication identified subgroups in whom there was minimal and maximal stimulation response. Patients in these subgroups had no differences between the MR imaging–determined actual electrode tip location and its intended location. Similarly, improvements of dyskinesias and severity of symptoms encountered during the wearing-off period for the drug did not correlate with variations of electrode tip location.
The findings in this study lead the authors to suggest that a DBS electrode placed anywhere within a 6-mm-diameter cylinder centered at the presumed middle of the STN (based on stereotactic atlas coordinates) provides similar clinical efficacy. Future studies may be warranted to evaluate prospectively the degree to which MER modification of the anatomically and/or image-determined target improves clinical efficacy of DBS electrodes.
Bharat Guthikonda, Emilie Rouah, Bhuvanaswari Krishnan, Suzanne Z. Powell, J. Clay Goodman, Shankar P. Gopinath and Richard K. Simpson
Whipple disease is a multisystem infectious disease caused by Tropheryma whippleii. It commonly affects the CNS and produces neurological symptoms in 10–20% of cases. Central nervous system Whipple disease occurring in patients with AIDS is extremely rare. The authors present a case of a newly diagnosed AIDS patient in whom intracranial Whipple disease was diagnosed by stereotactic brain biopsy.
Patrick B. Senatus, David Teeple, Shearwood McClelland III, Seth L. Pullman, Qiping Yu, Blair Ford, Guy M. McKhann II and Robert R. Goodman
Implantation of a subthalamic nucleus (STN) deep brain stimulation (DBS) electrode is increasingly recognized as an effective treatment for advanced Parkinson disease (PD). Despite widespread use of microelectrode recording (MER) to delineate the boundaries of the STN prior to stimulator implantation, it remains unclear to what extent MER improves the clinical efficacy of this procedure. In this report, the authors analyze a series of patients who were treated at one surgical center to determine to what degree final electrode placement was altered, based on readings obtained with MER, from the calculated anatomical target.
Subthalamic DBS devices were placed bilaterally in nine patients with advanced PD. Frame-based volumetric magnetic resonance images were acquired and then transferred to a stereotactic workstation to determine the anterior and posterior commissure coordinates and plane. The initial anatomical target was 4 mm anterior, 4 mm deep, and 12 mm lateral to the midcommissural point. The MERs defined the STN boundaries along one or more parallel tracks, refining the final electrode placement by comparison of results with illustrations in a stereotactic atlas.
In eight of 18 electrodes, the MER results did not prompt an alteration in the anatomically derived target. In another eight placements, MER altered the target by less than 1 mm and two of 18 electrode positions differed by less than 2 mm. The anterior–posterior difference was 0.53 ± 0.65 mm, whereas the medial–lateral direction differed by 0.25 ± 0.43 mm. The ventral boundary of the STN defined by MER was 2 ± 0.72 mm below the calculated target (all values are the means ± standard deviation). All patients attained clinical improvement, similar to previous reports.
In this series of patients, microelectrode mapping of the STN altered the anatomically based target only slightly. Because it is not clear whether such minor adjustments improve clinical efficacy, a prospective clinical comparison of MER-refined and anatomical targeting may be warranted.