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Cheerag D. Upadhyaya, Philip A. Starr and Praveen V. Mummaneni

Object

The authors review the literature on the treatment of spinal deformity in patients with Parkinson disease (PD) and formulate a treatment algorithm.

Methods

The authors provide representative cases of patients with PD and spinal deformity who underwent deep brain stimulation (DBS) or spinal surgery.

Results

In patients with PD and spinal deformity who undergo spinal surgery there is a high rate of acute and delayed complications. Patients who undergo DBS, while having significantly fewer complications, often do not regain sagittal balance.

Conclusions

Cases involving PD and camptocormia have a high rate of complications when spinal surgery is performed. The authors prefer to offer spinal surgery only to patients with coexisting spinal stenosis causing radiculopathy or myelopathy. Patients with PD and camptocormia without spinal stenosis may be considered for DBS, but the results are mixed.

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Philip A. Starr, Thyagarajan Subramanian, Roy A. E. Bakay and Thomas Wichmann

✓ During ablative surgery and implantation of deep-brain stimulators for the treatment of movement disorders, electrophysiological techniques are often used for localization of subcortical targets. New restorative therapies for Parkinson disease, aimed at delivering drugs or cells to the substantia nigra (SN), are becoming available. Therefore, precise surgical approaches to the dopaminergic cell—containing region of the SN are required to avoid damage to nearby structures such as the corticospinal tract and subthalamic nucleus. In a study conducted in nonhuman primates, the authors evaluated the utility and accuracy of electrophysiological techniques in localizing the SN.

Three adult rhesus monkeys were used as hosts for intranigral cell transplants. The monkeys were rendered hemiparkinsonian by intracarotid injection of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine. With the aid of stereotactic guidance, chronic recording chambers were placed on the skull of each monkey and directed at the SN. In each monkey, 20 to 40 trajectories were explored with a microelectrode. Spontaneous and movement-related single-unit activities were recorded in the SN, pars reticulata, subthalamic nucleus, globus pallidus, striatum, thalamus, and red nucleus. Motor and ocular responses to microstimulation in the subthalamic area were noted. Using the electrophysiological and stereotactic information that was obtained, three-dimensional maps of the nigral complex were constructed to infer the location of the SN pars compacta. The maps were subsequently used to guide intranigral placement of fetal dopaminergic cells. Accurate delivery was verified by histological analysis.

Based on the characteristic electrophysiological properties of the SN and surrounding structures in the parkinsonian state, microelectrode recording techniques may be used to ensure accurate placement of cell transplantation in the intranigral region.

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Ellen L. Air, Jill L. Ostrem, Terence D. Sanger and Philip A. Starr

Object

Deep brain stimulation (DBS) is an established technique for the treatment of several movement disorders in adults. However, the technical approach, complications, and results of DBS in children have not been well documented.

Methods

A database of DBS implantations performed at a single institution, prospectively established in 1998, was reviewed for patients who received DBS prior to the age of 18. Diagnoses, surgical technique, and complications were noted. Outcomes were assessed using standard rating scales of neurological function.

Results

Of 815 patients undergoing DBS implantation over a 12-year period, 31 were children (mean age at surgery 13.2 years old, range 4–17 years old). Diagnoses included the following: DYT1 primary dystonia (autosomal dominant, Tor1AΔGAG mutation, 10 cases), non-DYT1 primary dystonia (3 cases), secondary dystonia (11 cases), neurodegeneration with brain iron accumulation (NBIA, 3 cases), levodopa-responsive parkinsonism (2 cases), Lesch-Nyhan disease (1 case), and glutaric aciduria Type 1 (1 case). Six children ages 15–17 years old underwent awake microelectrode-guided surgery. For 25 children operated under general anesthesia, the surgical technique evolved from microelectrode-guided surgery to image-guided surgeries using real-time intraoperative MR imaging or CT for lead location confirmation. Complications included 5 hardware infections, all in children younger than 10 years old. At 1 year after implantation, patients with DYT1 dystonia had a mean improvement in the Burke-Fahn-Marsden Dystonia Rating Scale movement subscore of 75%, while those with secondary dystonia had only small improvements. Outcomes in the 3 children with NBIA were disappointing.

Conclusions

Results of DBS in children with primary and secondary dystonias were similar to those in adults, with excellent results for DYT1 dystonia in children without fixed orthopedic deformity and much more modest results in secondary dystonia. In contrast to reported experience in adults with NBIA, these results in children with NBIA were poor. Infection risk was highest in the youngest patients.

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Philip A. Starr, Nicholas M. Barbaro, Neil H. Raskin and Jill L. Ostrem

Object

Cluster headache (CH) is the most severe of the primary headache disorders. Based on the finding that regional cerebral blood flow is increased in the ipsilateral posterior hypothalamic region during a CH attack, a novel neurosurgical procedure for CH was recently introduced: hypothalamic deep brain stimulation (DBS). Two small case series have been described. Here, the authors report their technical approach, intraoperative physiological observations, and 1-year outcomes after hypothalamic DBS in four patients with medically intractable CHs.

Methods

Patients underwent unilateral magnetic resonance (MR) imaging–guided stereotactic implantation of a Medtronic DBS (model 3387) lead and Soletra pulse generator system. Intended tip coordinates were 3 mm posterior, 5 mm inferior, and 2 mm lateral to the midcommissural point. Microelectrode recording and intraoperative test stimulation were performed. Lead locations were measured on postoperative MR images. The intensity, frequency, and severity of headaches throughout a 1-week period were tracked in patient diaries immediately prior to surgery and after 1 year of continuous stimulation.

At the 1-year follow-up examination, DBS had produced a greater than 50% reduction in headache intensity or frequency in two of four cases. Active contacts were located 3 to 6 mm posterior to the mammillothalamic tract. Neurons in the target region showed low-frequency tonic discharge.

Conclusions

In two previously published case series, headache relief was obtained in many but not all patients. The results of these open-label studies justify a larger, prospective trial but do not yet justify widespread clinical application of this technique.

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Chadwick W. Christine, J. William Langston, Robert S. Turner and Philip A. Starr

Parkinsonism caused by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) exposure was first identified in intravenous drug users. This neurotoxicant has since been used extensively in nonhuman primates to induce an experimental model of Parkinson disease (PD). In this study, the authors examined the intraoperative physiological characteristics and efficacy of subthalamic nucleus deep brain stimulation (DBS) in 1 of only 4 known living patients with MPTP-induced parkinsonism. The physiological recordings were consistent with recordings from MPTP-treated primates and humans with PD, thus providing further validation for the MPTP model in the study of the neurophysiology of the nigrostriatal dopaminergic deficit in PD. Furthermore, DBS produced a significant clinical improvement in this patient similar to the improvement seen after DBS in patients with idiopathic PD. This unique case has important implications for translational research that employs the MPTP-primate model for symptomatic therapy in PD.

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Philip A. Starr, Chadwick W. Christine, Philip V. Theodosopoulos, Nadja Lindsey, Deborah Byrd, Anthony Mosley and William J. Marks Jr.

Object. Chronic deep brain stimulation (DBS) of the subthalamic nucleus (STN) is a procedure that is rapidly gaining acceptance for the treatment of symptoms in patients with Parkinson disease (PD), but there are few detailed descriptions of the surgical procedure itself. The authors present the technical approach used to implant 76 stimulators into the STNs of patients with PD and the lead locations, which were verified on postoperative magnetic resonance (MR) images.

Methods. Implantation procedures were performed with the aid of stereotactic MR imaging, microelectrode recording (MER) in the region of the stereotactic target to define the motor area of the STN, and intraoperative test stimulation to assess the thresholds for stimulation-induced adverse effects. All patients underwent postoperative MR imaging, which was performed using volumetric gradient-echo and T2-weighted fast—spin echo techniques, computational reformatting of the MR image into standard anatomical planes, and quantitative measurements of lead location with respect to the midcommissural point and the red nucleus. Lead locations were statistically correlated with physiological data obtained during MER and intraoperative test stimulation.

Conclusions. The authors' approach to implantation of DBS leads into the STN was associated with consistent lead placement in the dorsolateral STN, a low rate of morbidity, efficient use of operating room time, and robust improvement in motor function. The mean coordinates of the middle of the electrode array, measured on postoperative MR images, were 11.6 mm lateral, 2.9 mm posterior, and 4.7 mm inferior to the midcommissural point, and 6.5 mm lateral and 3.5 mm anterior to the center of the red nucleus. Voltage thresholds for several types of stimulation-induced adverse effects were predictive of lead location. Technical nuances of the surgery are described in detail.

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Camilla Kilbane, Adolfo Ramirez-Zamora, Elena Ryapolova-Webb, Salman Qasim, Graham A. Glass, Philip A. Starr and Jill L. Ostrem

OBJECT

Holmes tremor (HT) is characterized by irregular, low-frequency (< 4.5 Hz) tremor occurring at rest, with posture, and with certain actions, often affecting proximal muscles. Previous reports have tended to highlight the use of thalamic deep brain stimulation (DBS) in cases of medication-refractory HT. In this study, the authors report the clinical outcome and analysis of single-unit recordings in patients with medication-refractory HT treated with globus pallidus internus (GPi) DBS.

METHODS

The authors retrospectively reviewed the medical charts of 4 patients treated with pallidal DBS for medication-refractory HT at the University of California, San Francisco, and San Francisco Veterans Affairs Medical Center. Clinical outcomes were measured at baseline and after surgery using an abbreviated motor-severity Fahn-Tolosa-Marin (FTM) tremor rating scale. Intraoperative microelectrode recordings were performed with patients in the awake state. The neurophysiological characteristics identified in HT were then also compared with characteristics previously described in Parkinson's disease (PD) studied at the authors' institution.

RESULTS

The mean percentage improvement in tremor motor severity was 78.87% (range 59.9%–94.4%) as measured using the FTM tremor rating scale, with an average length of follow-up of 33.75 months (range 18–52 months). Twenty-eight GPi neurons were recorded intraoperatively in the resting state and 13 of these were also recorded during contralateral voluntary arm movement. The mean firing rate at rest in HT was 56.2 ± 28.5 Hz, and 63.5 ± 19.4 Hz with action, much lower than the GPi recordings in PD. GPi unit oscillations of 2–8 Hz were prominent in both patients with HT and those with PD, but in HT, unlike PD, these oscillations were not suppressed by voluntary movement.

CONCLUSIONS

The efficacy of GPi DBS exceeded that reported in prior studies of ventrolateral thalamus DBS and suggest GPi may be a better target for treating HT. These clinical and neurophysiological findings help illuminate evolving models of HT and highlight the importance of cerebellar–basal ganglia interactions.

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Andrew K. Chan, Alvin Y. Chan, Darryl Lau, Beata Durcanova, Catherine A. Miller, Paul S. Larson, Philip A. Starr and Praveen V. Mummaneni

OBJECTIVE

Camptocormia is a potentially debilitating condition in the progression of Parkinson’s disease (PD). It is described as an abnormal forward flexion while standing that resolves when lying supine. Although the condition is relatively common, the underlying pathophysiology and optimal treatment strategy are unclear. In this study, the authors systematically reviewed the current surgical management strategies for camptocormia.

METHODS

PubMed was queried for primary studies involving surgical intervention for camptocormia in PD patients. Studies were excluded if they described nonsurgical interventions, provided only descriptive data, or were case reports. Secondarily, data from studies describing deep brain stimulation (DBS) to the subthalamic nuclei were extracted for potential meta-analysis. Variables showing correlation to improvement in sagittal plane bending angle (i.e., the vertical angle caused by excessive kyphosis) were subjected to formal meta-analysis.

RESULTS

The query resulted in 9 studies detailing treatment of camptocormia: 1 study described repetitive trans-spinal magnetic stimulation (rTSMS), 7 studies described DBS, and 1 study described deformity surgery. Five studies were included for meta-analysis. The total number of patients was 66. The percentage of patients with over 50% decrease in sagittal plane imbalance with DBS was 36.4%. A duration of camptocormia of 2 years or less was predictive of better outcomes (OR 4.15).

CONCLUSIONS

Surgical options include transient, external spinal stimulation; DBS targeting the subthalamic nuclei; and spinal deformity surgery. Benefit from DBS stimulation was inconsistent. Spine surgery corrected spinal imbalance but was associated with a high complication rate.

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Derek G. Southwell, Harjus S. Birk, Paul S. Larson, Philip A. Starr, Leo P. Sugrue and Kurtis I. Auguste

Hypothalamic hamartomas (HHs) are benign lesions that cause medically refractory seizures, behavioral disturbances, and endocrine dysfunction. Open resection of HHs does not guarantee seizure freedom and carries a relatively high risk of morbidity. Minimally invasive stereotactic laser ablation has recently been described as an effective and safe alternative for HH treatment. Prior studies have not, however, assessed HH lesion size and morphology, 2 factors that may influence treatment results and, ultimately, the generalizability of their findings. In this paper, the authors describe seizure outcomes for 5 pediatric patients who underwent laser ablation of sessile HHs. Lesions were treated using a frameless, interventional MRI-guided approach, which facilitated laser targeting to specific components of these complex lesions. The authors’ experiences in these cases substantiate prior work demonstrating the effectiveness of laser therapy for HHs, while elucidating HH complexity as a potentially important factor in laser treatment planning, and in the interpretation of early studies describing this treatment method.