✓ Acute baclofen withdrawal syndrome is a life-threatening situation that demands early recognition and urgent treatment. The current therapy of choice for this syndrome is administration of intravenous benzodiazepines, propofol, and chemical paralytic drugs until the intrathecal system can be restored. The authors present a novel technique for administering baclofen intrathecally using a lumbar drain and a standard patient-controlled analgesia pump (in continuous infusion mode). In one case, this method was used to wean the patient from high-dose intrathecal baclofen treatment. In a second case, this method was used as a temporizing measure until the indwelling pump system could be repaired. In both cases, the patients recovered to their neurological baseline level, and lasting consequences of serious withdrawal were avoided.
Bradley S. Duhon and Joel D. Macdonald
Roukoz Chamoun, Joel MacDonald, Clough Shelton and William T. Couldwell
Surgical removal remains one of the key treatment modalities for vestibular schwannomas. A team approach between a neurotologist and a neurosurgeon offers the patient the expertise of both specialties and maximizes the chances for an optimal outcome. Vestibular schwannomas can typically be resected through 1 of 3 main surgical approaches: the translabyrinthine, the retrosigmoid, or the middle fossa approaches. In this report and videos, the authors describe and illustrate the indications and surgical techniques for the removal of these tumors.
James K. Liu, Christina M. Sayama, Clough Shelton and Joel D. MacDonald
✓Some evidence in the literature supports the topical application of papaverine to the cochlear nerve to prevent internal auditory artery vasospasm and cochlear ischemia as a method of enhancing the ability to preserve hearing during acoustic neuroma surgery. The authors report a case of transient facial nerve palsy that occurred after papaverine was topically applied during a hearing preservation acoustic neuroma removal. A 58-year-old woman presented with tinnitus and serviceable sensorineural hearing loss in her right ear (speech reception threshold 15 dB, speech discrimination score 100%). Magnetic resonance imaging demonstrated a 1.5-cm acoustic neuroma in the right cerebellopontine angle (CPA). A retrosigmoid approach was performed to achieve gross-total resection of the tumor. During tumor removal, a solution of 3% papaverine soaked in a Gelfoam pledget was placed over the cochlear nerve. Shortly thereafter, the quality of the facial nerve stimulation deteriorated markedly. Electrical stimulation of the facial nerve did not elicit a response at the level of the brainstem but was observed to elicit a robust response more peripherally. There were no changes in auditory brainstem responses. Immediately after surgery, the patient had a House–Brackmann Grade V facial palsy on the right side. After several hours, this improved to a Grade I. At the 1-month follow-up examination, the patient exhibited normal facial nerve function and stable hearing.
Intracisternal papaverine may cause a transient facial nerve palsy by producing a temporary conduction block of the facial nerve. This adverse effect should be recognized when topical papaverine is used during CPA surgery.
Warren R. Selman
Paul Klimo Jr., John R. W. Kestle, Joel D. MacDonald and Richard H. Schmidt
Cerebral vasospasm after subarachnoid hemorrhage (SAH) continues to be a major source of morbidity in patients despite significant clinical and basic science research. Efforts to prevent vasospasm by removing spasmogens from the subarachnoid space have produced mixed results. The authors hypothesize that lumbar cisternal drainage can remove blood from the basal subarachnoid spaces more effectively than an external ventricular drain (EVD). This nonrandomized, controlled-cohort study was undertaken to evaluate the effectiveness of a lumbar drain in patients with SAH compared with those in whom an EVD or no form of cerebrospinal fluid (CSF) drainage was used to prevent the development of clinical vasospasm and its sequelae.
The authors collected data on 266 patients with nontraumatic SAH who were admitted to the University of Utah Health Sciences Center between January 1994 and January 2003. Of these, 167 met the study entry criteria. The treatment group consisted of 81 patients in whom a lumbar drain had been placed for CSF shunting, whereas the control group was composed of 86 patients who received no form of CSF drainage or who were treated solely with an EVD. Primary outcome measures were as follows: 1) clinically evident vasospasm; 2) the need for endovascular intervention; 3) vasospasm-induced infarction; 4) disposition at time of discharge; and 5) Glasgow Outcome Scale (GOS) score at 1 to 3 months postdischarge. Secondary outcomes included length of stay and the need for CSF shunting.
The presence of a lumbar drain conferred a statistically significant protective and beneficial effect across all outcome measures, reducing the incidence of clinical vasospasm from 51 to 17%, the need for angioplasty from 45 to 17%, and the occurrence of vasospastic infarction from 27 to 7% (all p ≤ 0.001–0.008). Patients in the treatment group were more likely to be discharged home (54% compared with 25%, p = 0.002) and to have a GOS score of 5 at follow up (71% compared with 35%, p < 0.001). The mean number of days spent in the intensive care unit and in the hospital overall was also fewer in the treatment group. A similar degree of benefit was found in patients with different Fisher grades and regardless of whether an EVD was needed on presentation, both by subgroup analysis and multivariate logistic regression modeling. There was no statistical difference between the groups in terms of patients requiring a shunt. Complications with lumbar drains were rare and yielded no permanent sequelae.
Shunting of CSF through a lumbar drain after an SAH markedly reduces the risk of clinically evident vasospasm and its sequelae, shortens hospital stay, and improves outcome. Its beneficial effects are probably mediated through the removal of spasmogens that exist in the CSF. The results of this study warrant a randomized clinical trial, which is currently under way.
Paul A. House, Joel D. MacDonald, Patrick A. Tresco and Richard A. Normann
Researchers at The Center for Neural Interfaces at the University of Utah have designed and produced a silicon-based high-density microelectrode array that has been used successfully in mammalian models. The authors investigate the ability to transfer array insertion techniques to humans and examine the acute response of human cortical tissue to array implantation.
Six patients who were scheduled to undergo temporal lobectomy surgery were enrolled in an Institutional Review Board–approved protocol. Before the patients underwent lateral temporal cortical resection, one or two high-density microelectrode arrays were implanted in each individual by using a pneumatic insertion device. Cortical tissue was then excised and preserved in formalin. The specimens were sectioned and stained for histological examination.
Pneumatic insertion of a microelectrode array into human cortex in the operating room was feasible. There were no clinical complications associated with implantation and no evidence of significant insertion-related hemorrhage. Tissue responses ranged from mild cortical deformity to small focal hemorrhages several millimeters below the electrode tines. Based on initial results, the insertion device was modified. A footplate that mechanically isolates a small area of cortex and a calibrated micromanipulator were added to improve the reproducibility of insertion.
A high-density microelectrode array designed to function as a direct cortical interface device can be implanted into human cortical tissue without acute clinical complications. Further modifications to the insertion device and array design are ongoing and future work will assess the functional significance of the tissue reactions observed.
James K. Liu, Meic H. Schmidt, Joel D. Macdonald, Randy L. Jensen and William T. Couldwell
Stereotactic radiosurgery (SRS) is performed with increasing frequency in the treatment of residual or recurrent pituitary adenomas. Its major associated risk in these cases of residual or recurrent pituitary tumor adjacent to normal functional pituitary gland is radiation exposure to the pituitary, which frequently leads to the development of hypopituitarism. The authors describe a technique of pituitary transposition to reduce the radiation dose to the normal pituitary gland in cases of planned radiosurgical treatment of residual pituitary adenoma within the cavernous sinus. A sellar exploration for tumor resection is performed, the pituitary gland is transposed from the region of the cavernous sinus, and a fat and fascia graft is interposed between the normal pituitary gland and the residual tumor in the cavernous sinus. The residual tumor may then be treated with SRS. The increased distance between the normal pituitary gland and the residual tumor facilitates treatment of the tumor with radiosurgery and reduces radiation exposure to the normal pituitary gland.
William T. Couldwell, Joel D. MacDonald, Charles L. Thomas, Bradley C. Hansen, Aniruddha Lapalikar, Bharat Thakkar and Alagar K. Balaji
The authors have developed a simple device for computer-aided design/computer-aided manufacturing (CAD-CAM) that uses an image-guided system to define a cutting tool path that is shared with a surgical machining system for drilling bone. Information from 2D images (obtained via CT and MRI) is transmitted to a processor that produces a 3D image. The processor generates code defining an optimized cutting tool path, which is sent to a surgical machining system that can drill the desired portion of bone. This tool has applications for bone removal in both cranial and spine neurosurgical approaches. Such applications have the potential to reduce surgical time and associated complications such as infection or blood loss. The device enables rapid removal of bone within 1 mm of vital structures. The validity of such a machining tool is exemplified in the rapid (< 3 minutes machining time) and accurate removal of bone for transtemporal (for example, translabyrinthine) approaches.
Paul House, Karen L. Salzman, Anne G. Osborn, Joel D. MacDonald, Randy L. Jensen and William T. Couldwell
Object. Dilations of brain perivascular spaces (PVSs), also known as Virchow—Robin spaces, are routinely identified on magnetic resonance imaging studies of the brain and recognized as benign normal variants. Giant dilations occur only rarely and can be easily misdiagnosed as central nervous system tumors. The relevant surgical literature was reviewed to help establish indications for surgical intervention in these typically benign lesions.
Methods. Giant dilations of the PVSs in 12 patients who had undergone surgery for several different indications were identified. Both clinical and radiographic presentations of these patients were reviewed along with the surgical procedures.
Conclusions. Dilations of the PVSs can become giant lesions that may necessitate surgical intervention to relieve mass effect or hydrocephalus. The relationship of these lesions to neurological symptoms such as tremor and seizures remains unclear.