Anish N. Sen

Deep brain stimulation in the management of disorders of consciousness: a review of physiology, previous reports, and ethical considerations

Patients suffering from disorders of consciousness constitute a population that exists largely outside of the daily practice patterns of neurosurgeons. Historically, treatment has focused on nursing and custodial issues with limited neurosurgical intervention. Recently, however, deep brain stimulation has been explored to restore cognitive and physical function to patients in minimally conscious states. In this article, the authors characterize the physiological mechanisms for the use of deep brain stimulation in persistently vegetative and minimally conscious patients, review published cases and associated ethical concerns, and discuss future directions of this technology.

Emergency Reversal of Clopidogrel in the Setting of Spontaneous Intracerebral Hemorrhage

OBJECTIVE To compare outcomes in the setting of spontaneous intracerebral hemorrhage (ICH) in patients taking aspirin (acetylsalicylic acid [ASA]) versus patients taking clopidogrel before hospitalization. METHODS Patients admitted to the neurosurgical service with a spontaneous ICH while taking an antiplatelet agent were prospectively identified and retrospectively reviewed. Two groups of 28 consecutive patients taking ASA or clopidogrel on admission were ultimately evaluated. RESULTS Patients in the clopidogrel group had a mean age of 72.6 years, and patients in the ASA group had a mean age of 65.8 years (P=0.04). Patients taking clopidogrel before hospitalization were significantly more likely than patients taking ASA to experience an increase in hematoma volume (P=0.05). Patients in the ASA group trended toward being discharged to home more frequently than other destinations (P=0.07). The in-hospital mortality rates in this series were 14.3% for the ASA group and 28.6% for the clopidogrel group. However, this association did not reach statistical significance (P=0.19). CONCLUSIONS In this study, patients taking clopidogrel showed more hematoma expansion, higher in-hospital mortality rates, and a decreased likelihood of a home discharge compared with patients taking ASA alone.

Fixation with C-2 laminar screws in occipitocervical or C1–2 constructs in children 5 years of age or younger: a series of 18 patients

UNLABELLED OBJECT.: There are rare indications for upper cervical spine fusion in young children. Compared with nonrigid constructs, rigid instrumentation with screw fixation increases the fusion rate and reduces the need for halo fixation. Instrumentation may be technically challenging in younger children. A number of screw placement techniques have been described. Use of C-2 translaminar screws has been shown to be anatomically feasible, even in the youngest of children. However, there are few data detailing the clinical outcome. In this study, the authors describe the clinical and radiographic follow-up of 18 children 5 years of age or younger who had at least one C-2 translaminar screw as part of an occipitocervical or C1-2 fusion construct. METHODS A retrospective review of all children treated with instrumented occipitocervical or C1-2 fusion between July 1, 2007, and June 30, 2013, at Riley Childrens Hospital and Texas Childrens Hospital was performed. All children 5 years of age or younger with incorporation of at least one C-2 translaminar screw were identified. RESULTS Eighteen children were studied (7 boys and 11 girls). The mean age at surgery was 38.1 months (range 10-68 months). Indications for surgery included traumatic instability (6), os odontoideum (3), destructive processes (2), and congenital instability (7). A total of 24 C-2 translaminar screws were placed; 23 (95.8%) of 24 were satisfactorily placed (completely contained within the cortical walls). There was one medial cortex breach without neurological impingement. There were no complications with screw placement. Three patients required wound revisions. Two patients died as a result of their original condition (trauma, malignant tumor). The mean follow-up duration for the surviving patients was 17.5 months (range 3-60 months). Eleven (91.7%) of the 12 patients followed for 6 months or longer showed radiographic stability or completed fusion. CONCLUSIONS Use of C-2 translaminar screws provides an effective anchor for internal fixation of the upper cervical spine. In this study of children 5 years of age or younger, the authors found a high rate of radiographic fusion with a low rate of complications.

Estimation of normal computed tomography measurements for the upper cervical spine in the pediatric age group

OBJECT Upper cervical spine injuries in the pediatric age group have been recognized as extremely unstable from ligamentous disruption and as potentially lethal. Few measurement norms have been published for the pediatric upper cervical spine to help diagnose this pathological state. Instead, adult measurement techniques and results are usually applied inappropriately to children. The authors propose using high-resolution reconstructed CT scans to define a range of normal for a collection of selected upper cervical spine measurements in the pediatric age group. METHODS Sagittal and coronal reformatted images were obtained from thin axial CT scans obtained in 42 children (< 18 years) in a 2-month period. There were 25 boys and 17 girls. The mean age was 100.9 months (range 1-214 months). Six CT scans were obtained for nontrauma indications, and 36 were obtained as part of a trauma protocol and later cleared for cervical spine injury. Six straightforward and direct linear distances-basion-dental interval (BDI); atlantodental interval (ADI); posterior atlantodental interval (PADI); right and left lateral mass interval (LMI); right and left craniocervical interval (CCI); and prevertebral soft-tissue thickness at C-2-that minimized logistical and technical distortions were measured and recorded. Statistical analysis including interobserver agreement, age stratification, and sex differences was performed for each of the 6 measurements. RESULTS The mean ADI was 2.25 ± 0.24 mm (± SD), the mean PADI was 18.3 ± 0.07 mm, the mean BDI was 7.28 ± 0.10 mm, and the mean prevertebral soft tissue width at C-2 was 4.45 ± 0.43 mm. The overall mean CCI was 2.38 ± 0.44 mm, and the overall mean LMI was 2.91 ± 0.49 mm. Linear regression analysis demonstrated statistically significant age effects for PADI (increased 0.02 mm/month), BDI (decreased 0.02 mm/month), and CCI (decreased 0.01 mm/month). Similarly significant effects were found for sex; females demonstrated on average a smaller CCI by 0.26 mm and a smaller PADI by 2.12 mm. Moderate to high interrater reliability was demonstrated across all parameters. CONCLUSIONS Age-dependent and age-independent normal CT measurements of the upper cervical spine will help to differentiate physiological and pathological states in children. The BDI appears to change significantly with age but not sex; on the other hand, the LMI and ADI appear to be age-independent measures. This preliminary study suggests acceptable levels of interrater reliability, and further expanded study will aim to validate these measurements to produce a profile of normal upper cervical spine measurements in children.

Clinical application of near-infrared spectroscopy in patients with traumatic brain injury: a review of the progress of the field

Abstract. Near-infrared spectroscopy (NIRS) is a technique by which the interaction between light in the near-infrared spectrum and matter can be quantitatively measured to provide information about the particular chromophore. Study into the clinical application of NIRS for traumatic brain injury (TBI) began in the 1990s with early reports of the ability to detect intracranial hematomas using NIRS. We highlight the advances in clinical applications of NIRS over the past two decades as they relate to TBI. We discuss recent studies evaluating NIRS techniques for intracranial hematoma detection, followed by the clinical application of NIRS in intracranial pressure and brain oxygenation measurement, and conclude with a summary of potential future uses of NIRS in TBI patient management.

Occipital Artery Pseudoaneurysm After Posterior Fossa Craniotomy

BACKGROUND Pseudoaneurysms of scalp arteries have been reported in rare cases after iatrogenic injury; however, they are far more commonly seen after traumatic injuries. They are usually associated with the superficial temporal artery; however, there have been a few reports of psuedoaneurysms of the occipital artery (OA). CASE DESCRIPTION We present a unique case of an OA pseudoaneurysm presenting with delayed postoperative hemorrhage after a retrosigmoid craniotomy. The pseudoaneurysm was treated by coil embolization. CONCLUSIONS The patient recovered fully after endovascular embolization. Other treatment options for pseudoaneurysms of facial, temporal, and scalp arteries include surgical clipping/trapping with excision, Hunterian ligation, or direct compression. Pseudoaneurysms of extracranial scalp arteries are rare and most often caused by traumatic compression of the artery against a bony ridge. Despite their rarity, pseudoaneurysms secondary to iatrogenic injury to extracranial arteries should be considered in the differential diagnosis in patients presenting with delayed incisional pain, redness, and swelling.

Spatial distribution of nonlinear interactions in subthalamic nucleus local field potentials in Parkinson'S disease

Abnormally synchronized neural oscillations within the subthalamic nucleus have been proposed as a contributor to the pathophysiology of Parkinsons disease. Recent studies have demonstrated phase-amplitude coupling between beta rhythms and high frequency oscillations in the subthalamic nucleus in unmedicated Parkinsonian patients. However, the nature of this coupling remains unclear. In this study, we first show the presence of nonlinear interactions between different frequency bands of oscillations. Then, we demonstrate that the amplitude of spatially localized high frequency activity is phase coupled with widespread beta oscillations within the subthalamic nucleus.

Intraoperative macroelectrode local field potential recordings in Essential Tremor

Essential Tremor (ET) is a common movement disorder involving the presence of action tremor. While there are pharmacological treatment options, Deep Brain stimulation (DBS) of the ventral intermediate nucleus (VIM) of the thalamus is an effective and widely used surgical therapy for those patients who are intolerant of, or whose tremor is unresponsive to, medications. In this study, we recorded local field potentials (LFPs) at various depths along the trajectory to Vim in three ET patients. LFP recordings at various depths were processed by a PCA based de-noising method to remove ECG artifacts. The spectral characteristics of LFPs were investigated via frequency-vs-depth maps using a modified Welch periodogram using robust statistics, and further analyzed within different sub-bands to determine whether LFP activity encodes characteristic patterns for the identification of disease-specific subcortical areas. Our results demonstrated that a median-based spectrum estimation approach eliminates outliers better than the traditional averaging technique by preserving band-specific LFP activity. Results indicate that there was clear oscillatory beta activity around 20 Hz in two subjects. One patient displayed relatively high gamma (40 Hz) activity in the sub-thalamic region. In conclusion, despite the small number of subjects, the present study adds to existing knowledge about LFP-based pathophysiology of ET and its target-based spectral activities.

Persistent Altered Mental Status in a Patient With Human Immunodeficiency Virus

A57-year-old man with human immunodeficiency virus (HIV) infection (diagnosed and treated since 2007), diabetes mellitus, hypertension, and treated pulmonary tuberculosis presented to the emergency department with 1 month of progressively worsening lethargy and personality changes, including remaining in bed all day, being minimally verbal, and having significant difficulty with ambulation. Physical examination and vital signswerewithin normal limits. On neurological examination, he was awake, alert, and oriented to name and hospital. His speech output was decreased, and his comprehension was poor. Cranial nerve examination demonstrated no significant abnormalities. Other pertinent positive examination findings included 4/5 strength with his left upper extremity. Sensory and reflex examinations were intact. Laboratory examination results included the following: CD4 count of 578 cells/mm, HIV viral load less than 20 copies/mL, a serum rapid plasma reagin titer of 4, toxoplasmosis IgG titer of 7.4 IU/mL (7.1 or less, not detected), and a serum Cryptococcus antigen titer of 4 (normal, 0). Lumbar puncture showed a nonreactive venereal diseases research laboratory, Cryptococcus antigen negative, total protein level of 80.7 mg/dL, glucose level of 174 mg/dL, red blood cell count of 4/μL, white blood cell (WBC) count of 2/μL, and negative Gram stain and culture. Magnetic resonance imaging (MRI) of the brain demonstrated T2/fluid attenuation inversion recovery (FLAIR) hyperintensities in the genu of the corpus callosum, frontal corona radiata, and bilateral centrum semiovale more on the left side (see Fig. 1).Without clear evidence of HIVencephalopathy and with a positive rapid plasma reagin and Cryptococcus antigen, the patient was treated empirically for neurosyphilis with a 14-day course of penicillin G, for Cryptococcus with fluconazole, and for toxoplasmosis. He clinically improved before his discharge. Three weeks later, he was readmitted with worsening confusion and generalized weakness and a new symptom of urinary incontinence. He denied fever. A second lumbar puncture was performed, and it showed the following: venereal diseases research laboratory nonreactive, Cryptococcus antigen negative, total protein level of 83.1 mg/dL, glucose level of 67 mg/dL, red blood cell count of 58/μL, and WBC count of 2/μL. Complete blood cell count showed WBC count of 4.0 K/μL, hemoglobin level of 13.2 g/dL, platelet count of 219, lactate dehydrogenase of 251 U/L, and albumin level