Deep Brain Stimulation for Parkinson’s Disease - A Review

The majority of patients with Parkinson’s disease (PD) can be treated with medications. As the disease progresses, however, certain symptoms may evolve that are refractory to medical therapy but ideally suited to surgical intervention. Tremor, dyskinesia and motor fluctuation can be effectively treated with deep brain stimulation (DBS). This article highlights which PD patients can benefit from DBS and summarises how the operations are performed and what are the expected outcomes (and potential complications). The relevant literature is reviewed for experienced clinicians and our personal bias is highlighted for those new to the field (and hoping to avoid our early mistakes).

The importance of autonomic symptoms in trigeminal neuralgia

Object

Autonomic symptoms can occur in association with the facial pain of trigeminal neuralgia (TN). The distinction between first division (V1) TN and trigeminal autonomic cephalgias, particularly short-lasting unilateral neuralgiform headache with conjunctival injection and tearing (SUNCT), can be difficult. The goal in this study was to investigate the frequency of autonomic symptoms with TN and to determine their effect on surgical outcome.

Methods

The authors sent questionnaires and reviewed the records of 92 patients who underwent surgical procedures for TN to obtain visual analog scale scores for pain before and after surgery and to determine the location of the pain and the presence of autonomic symptoms.

Results

Sixty-seven percent of patients had at least 1 autonomic symptom, and 14% had 4 or more autonomic symptoms associated with their pain. With V1 pain, the most common autonomic symptoms were conjunctival injection, ptosis, and excessive tearing. With pain involving the second division (V2), facial swelling was the most common autonomic symptom. Excessive salivation occurred most often when the pain involved the third division (V3). In patients who underwent microvascular decompression (MVD), visual analog scores for pain showed significantly greater improvement postoperatively in those who had no preoperative autonomic symptoms than in those who reported autonomic symptoms. There was also a significantly greater number of patients who were pain free postoperatively in the group without autonomic symptoms. There were 3 patients with V1 facial pain associated with conjunctival injection and tearing who, in retrospect, fulfilled all the current diagnostic criteria for SUNCT. These patients underwent MVD, during which a vessel was found to compress the trigeminal nerve. Postoperatively, the 3 patients experienced complete and long-lasting pain relief.

Conclusions

The presence of autonomic symptoms in TN correlated with a worse prognosis for pain relief after MVD. First division TN with autonomic symptoms can present identically to SUNCT but can respond to MVD if there is a compressive vessel. Neurosurgeons should be aware of SUNCT, especially in patients with V1 TN and autonomic symptoms, to ensure that all potential medical therapies have been tried prior to surgical treatment.

Minimizing brain shift during functional neurosurgical procedures - a simple burr hole technique that can decrease CSF loss and intracranial air

BACKGROUND

Exact stereotactic placement of deep brain stimulation electrodes during functional stereotactic neurosurgical procedures can be impeded by intraoperative brain shift. Brain shift has been shown to correlate with the amount of intracranial (subdural) air detected on early postoperative imaging studies. We report a simple burr hole technique that reduces the loss of cerebrospinal fluid (CSF) and has the potential to significantly reduce the amount of postoperative intracranial air.

MATERIAL AND METHODS

A total of 16 patients were studied with half (group 2) receiving the burr hole technique designed to seal the CSF space and thereby reducing CSF loss. The other 8 patients (group 1) received the standard burr hole technique. The 2 groups were of similar age, gender, diagnosis (Parkinson's disease, n=14; cervical dystonia n=2), and surgical targets. All patients received bilateral electrodes either in the subthalamic nucleus (STN, n=14) or in the globus pallidum internus (GPi, n=2) avoiding transventricular trajectories. Early postoperative 3-dimensional computed tomography (3D CT) was used to check for possible bleeding, DBS lead location, and the amount of intracranial air. Intracranial air was assessed manually in a volumetric slice-by-slice approach in the individual postoperative CT and the groups compared by t-test.

RESULTS

Group 2 showed significantly lower postoperative intracranial air volumes (4.86 ± 4.35cc) as compared to group 1 (27.59 ± 17.80 cc, p=0.0083*). The duration of surgery, however, was significantly longer for group 1 (435 ± 56.05 min) as compared to group 2 (316 ± 34.79 min,p=0.00015*).The time span between the conclusion of the operation and postoperative 3DCT was similar for both groups.

CONCLUSION

This new and simple burr hole technique was associated with a significant reduction in postoperative intracranial air. Reduction of intracranial air will ultimately reduce brain shift. That total operation time does not influence intracranial air is discussed as well as the limitations of this pilot series. In the authors' opinion, this straightforward and cost-effective technique has the potential to reduce brain shift and to increase DBS placement accuracy during functional stereotactic neurosurgical procedures performed in the seated or half-sitting position. A larger more standardized patient series is necessary to substantiate the findings.

Severe agitation following deep brain stimulation for parkinsonism

The use of deep brain stimulation has become increasingly common for the treatment of movement disorders, including Parkinson disease. Although deep brain stimulation is generally very successful in alleviating the extrapyramidal symptoms of Parkinson disease, side effects can occur. This case report describes a patient presenting to the emergency department in a state of extreme aggression 3 days after a change in the parameters of his bilateral subthalamic nucleus stimulator. We review the complications of deep brain stimulation relevant to the emergency physician and provide some practical information on stimulator adjustment in an emergency.

Thalamic stimulation in multiple sclerosis: evidence for a ‘demyelinative thalamotomy’

The mechanism of action of deep brain stimulation (DBS) in the alleviation of tremor in multiple sclerosis (MS) and other neurological disorders is unknown. Moreover, whether the trauma accompanying this surgery is responsible for the induction of new MS plaques is controversial. Here we report the first description of the post-mortem imaging and pathologic findings in the brain of a MS patient who underwent thalamic DBS for the treatment of MS-induced tremor. MR imaging of formalin-fixed brain slices was carried out at 1.5, 3 and 7 Tesla and correlated with the histopathology. There were numerous demyelinative plaques in the white mater, cortex and deep gray matter. There were no plaques along the DBS tract within the sections that sampled the deep hemispheric white matter. However, deep within the thalamus focal demyelination approximated the tract, particularly in the region corresponding to the electrical field. The findings in this single case raise the possibility that focal demyelination may be induced by the electrical field and this may be responsible for long-lasting alleviation of tremor in the absence of continued electrostimulation.

Medial forebrain bundle stimulation as a pathophysiological mechanism for hypomania in subthalamic nucleus deep brain stimulation for Parkinson's disease

OBJECTIVE

Hypomania accounts for approximately 4% to 13% of psychotropic adverse events during subthalamic nucleus (STN) deep brain stimulation (DBS) for Parkinson's disease. Diffusion of current into the inferior and medial "limbic" STN is often reported to be the cause. We suggest a different explanation, in which the coactivation of the medial forebrain bundle (MFB), outside the STN, leads to hypomania during STN DBS.

METHODS

Six patients with advanced Parkinson's disease (age, 54 +/- 11 years) underwent bilateral STN DBS surgery. Preoperative diffusion tensor imaging scans for fiber tracking of the MFB were conducted on a 3T magnetic resonance imaging scanner. After implantation, the electrode positions were determined with computed tomography and integrated in a diffusion tensor imaging software environment.

RESULTS

The medial STN was shown to send tributaries to the MFB using it as a pathway to connect to the reward circuitry. One patient, who had a transient, stimulation-induced acute hypomanic episode, showed a direct contact between 1 active electrode contact and these putative limbic STN tributaries to the MFB unilaterally on the left. In 5 asymptomatic patients, the active contacts were between 2.9 and 7.5 mm distant from the MFB or its limbic STN tributaries.

CONCLUSION

We hypothesize that STN DBS-induced reversible acute hypomania might be elicited by inadvertent and unilateral coactivation of putative limbic STN tributaries to the MFB. These findings may provide insight into the neural pathways of hypomania and may facilitate future investigations of the pathophysiology of mood disorders.

Localization of the subthalamic nucleus: optimization with susceptibility-weighted phase MR imaging

BACKGROUND AND PURPOSE

On clinical MR images, the subthalamic nuclei (STN) are poorly delineated from adjacent structures, impeding safe direct targeting for placement of electrodes in the treatment of Parkinson disease. Susceptibility-weighted MR phase imaging offers improved contrast and spatial resolution at reduced imaging times relative to clinically used T2-weighted spin-echo imaging for STN visualization. Our purpose was to assess STN visibility by using phase imaging, comparing phase and magnitude images obtained concurrently by using susceptibility-weighted imaging (SWI). The goal was to identify an efficient scanning protocol for high-quality phase images of STN.

MATERIALS AND METHODS

Seventy-eight SWI scans were acquired at 3T by using different TEs and acceleration factors. STN visibility and delimitation from adjacent structures were scored from 0 (not interpretable) to 5 (excellent). Regression analyses assessed the relationship of STN visibility to scanning parameters

RESULTS

STN were identified at all studied TEs on phase images. Visibility and delimitation of STN were consistently superior on phase images compared with magnitude images. Good visualization (score of >or=4) of STN on phase imaging occurred at a mean TE of 20.0 ms and a sensitivity encoding (SENSE) of 1.40. Scores of STN visualization on phase images were dependent on SENSE (P < .002) and TE (P < .031). Good delimitation of the STN on phase imaging occurred at a mean TE of 21.6 ms and a SENSE of 1.36.

CONCLUSIONS

Visualization and delimitation of STN was superior on phase images and was achieved at 3T in <2.5 minutes. A TE of 20 ms and an acceleration factor of <or=1.5 are recommended to visualize STN by using this method.

Brown-Sèquard syndrome produced by C3-C4 cervical disc herniation: a case report and review of the literature

STUDY DESIGN

The article presents a case in which Brown-Sèquard syndrome resulted from a painless C3-C4 disc herniation.

OBJECTIVE

To raise spinal surgeons' awareness of this unusual clinical problem.

SUMMARY OF BACKGROUND DATA

Brown-Sèquard syndrome involves ipsilateral loss of motor function combined with contralateral loss of pain and temperature sensation. Brown-Sèquard syndrome is commonly seen in the setting of spinal trauma or an extramedullary spinal neoplasm, but rarely it can be caused by a herniated cervical disc.

METHODS

A 46-year-old man presented with progressive numbness and weakness in the left arm, mild neck pain, and reduced temperature sensation on the right side of the body. There was weakness in left arm and leg and proximal right lower limb. Magnetic resonance imaging showed large C3-C4 disc herniation compressing the spinal cord at that level. Anterior cervical discectomy and fusion with iliac crest bone graft was performed.

RESULTS

Follow-up showed complete resolution of the neck pain, normal sensory function, and complete recovery of motor power in the left upper and right lower limb. There was a slight residual weakness in the left leg.

CONCLUSION

Brown-Sèquard syndrome is rarely caused by a cervical disc herniation. This etiology may be underdiagnosed but has a more favorable outcome in those cases where rapid diagnosis is followed by spinal cord decompression.

Recurrent trigeminal neuralgia secondary to Teflon felt

The authors present a case of a 45-year-old man with recurrent trigeminal neuralgia twelve years after microvascular decompression. The patient underwent surgical reexploration of the trigeminal nerve. A piece of hardened Teflon felt was found piercing a hole through the trigeminal nerve. No other compression of the nerve was found. Removal of the Teflon felt resolved the neuralgia. To the authors knowledge this is the first report of recurrent trigeminal neuralgia due to such a mechanism. This case emphasises the need for further improvement of the surgical technique for microvascular decompression of the trigeminal neuralgia.

Three-tesla magnetic resonance imaging of the ventrolateral thalamus: a correlative anatomical description

Object

Surgery for tremor targets the ventrolateral nuclei of the thalamus. An initial radiological estimation of this target can be further refined through intraoperative physiological confirmation. Direct visualization of these nuclei has not yet been described. The improved signal-to-noise ratio associated with 3-tesla (3T) magnetic resonance (MR) imaging makes increased spatial resolution possible, which may aid in the identification of subtle morphological features. This study was conducted to describe the anatomy of the nuclei and fiber projections within the ventral thalamus by using 3T MR imaging.

Methods

Using a commercially available 3T MR unit, the authors obtained images of a formalin-fixed, paraffin-embedded brain. Slices with a 2-mm thickness and 0.2-mm gap were obtained parallel to the anterior commissure–posterior commissure (AC–PC) line. The brain was then sectioned through the cerebral hemispheres to obtain tissue slices encompassing the same levels. Adjacent 10-μm paraffin sections from the middle of each level were stained with Luxol fast blue and cresyl violet. The MR image and histological sections at the level of the AC–PC line were then compared in detail. In a separate study, the human thalamus was scanned in vivo using 3T and 1.5T MR imaging for anatomical comparison.

Conclusions

The anatomy of the nuclei and fiber projections within the ventrolateral thalamus in humans can be described using 3T MR imaging. The findings were reproducible in vivo with 3T but not 1.5T MR imaging. Additional studies are needed to confirm the accuracy of this observation for clinical purposes.

Hypomania as an adverse effect of subthalamic nucleus stimulation: report of two cases

Mania following subthalamic nucleus (STN) deep brain stimulation (DBS) is well described and obvious to both the patient and their physician. The authors describe two patients who developed hypomania following STN-DBS but were unaware of their mood disturbance. Two Parkinson's patients with no previous mood disorders received bilateral STN electrodes. Both experienced dramatic improvement in their motor function and neither complained of any side effects. Their families reported detrimental hypomanic behaviour. Readjusting the stimulation parameters resolved the hypomania with continued motor benefits. The authors draw attention to potential adverse effects of STN-DBS that might be neglected by patients.

Expectation and the placebo effect in Parkinson's disease patients with subthalamic nucleus deep brain stimulation

To determine whether the degree to which a patient with Parkinson's disease expects therapeutic benefit from subthalamic nucleus-deep brain stimulation (STN-DBS) influences the magnitude of his or her improved motor response, 10 patients with idiopathic Parkinson's and bilateral STN-DBS were tested after a 12-hour period off medication and stimulation. Four consecutive UPDRS III scores were performed in the following conditions: (a) stimulation OFF, patient aware; (b) stimulation OFF, patient blind; (c) stimulation ON, patient aware; and (d) stimulation ON, patient blind. Statistical significance (P = 0.0001) was observed when comparing main effect ON versus OFF (mean ON: 32.55; mean OFF: 49.15). When the stimulation was OFF, patients aware of this condition had higher UPDRS motor scores than when they were blinded (mean: 50.7 vs. 47.6). With the stimulation ON, UPDRS motor scores were lower when the patients were aware of the stimulation compared with when they were blinded (mean: 30.6 vs. 34.5). The interaction between these levels was significant (P = 0.049). This variation was important for bradykinesia and was not significant for tremor and rigidity. The authors conclude that the information about the condition of the stimulation enhanced the final clinical effect in opposite directions. The results presented support the role of expectation and placebo effects in STN-DBS in Parkinson's disease patients.

Artistic assault: an unusual penetrating head injury reported as a trivial facial trauma

The authors report a case of penetrating head injury that presented with a deceptively mild complaint. To our knowledge, it is the first report of a paint brush penetrating the brain. The patient reported being punched in the left eye and presented with a minor headache, swelling around the left orbit, a small cut on the cheek and slightly reduced left eye abduction. After radiological evaluation, a penetrating head injury was diagnosed. Under general anesthesia, through a lateral eyelid incision a 10.5 cm long paint brush, which had penetrated from the left orbit to the right thalamus, was removed. No post-operative infection was seen at six months follow-up. This brief report serves to highlight that penetrating brain injury can occur without neurological deficit and that a minimally invasive surgical approach was successful in avoiding any complications.

Tremor induced by thalamic deep brain stimulation in patients with complex regional facial pain

We report on two patients who developed a new postural and action tremor after chronic stimulation of the contralateral thalamus (VPM nucleus) during treatment of a complex regional facial pain syndrome. The tremor was only present during deep brain stimulation (DBS) and was suppressed with adjustment of the stimulation parameters. Tremor was seen only with low frequency stimulation (50 Hz or lower) and disappeared with higher stimulation frequencies. In addition to being an unusual side effect of thalamic DBS, we believe that this phenomenon affords insight into one possible mechanism underlying essential tremor (ET). A central oscillatory mechanism involving the olivocerebellar complex and the thalamus, which is a part of the cerebro-cerebello-cerebral circuit, is thought to play an important role in the genesis of ET. Induction of a tremor resembling ET in our patients indicates an active role for low frequency stimulation. A plausible explanation for this is that low frequency stimulation in the thalamic area enhances the output of the tremor-producing network. This leads credence to the concept of central oscillations in a "tremor circuit," of which the thalamus is a part, as being important in ET.

Percutaneous Radiofrequency Trigeminal Rhizotomy in a Patient with an Implanted Cardiac Pacemaker

Percutaneous radiofrequency ablation is a frequently used treatment for trigeminal neuralgia. Radiofrequency is another potential source of electromagnetic interference to implanted cardiac pacemakers. Our patient had a permanent pacemaker and underwent the procedure without incident.

PET imaging of implanted human retinal pigment epithelial cells in the MPTP-induced primate model of Parkinson's disease

Human retinal pigment epithelial (hRPE) cells produce L-dopa, are easily harvested and expanded in culture, and, attached to microcarriers, can survive in the brain without immunosuppression. Studies in rats, primates, and parkinsonian patients have demonstrated that striatally implanted hRPE cells attached to gelatin microcarriers (RPE-GM) are able to improve parkinsonian symptoms and are well tolerated for extended periods. In moderately to severely impaired monkeys with bilateral 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine hydrochloride (MPTP)-induced parkinsonism receiving a unilateral RPE-GM implant in the putamen, there was a 39% improvement in clinical scores over the first 2 months post-implant. Positron emission tomography (PET) with [18F]fluoro-L-dopa (FDOPA) showed increased accumulation in the implanted putamen and a concomitant decrease in [11C]raclopride binding in the same area, suggesting increased dopamine release compared to the contralateral putamen. We report the first in vivo visualization of hRPE cells and their effects, implicating a dopaminergic mechanism of action.