Minnesota Neurosurgical Society

Redwing, Minnesota; St. James Hotel

Notes from the Meeting (Anthony G. Bottini, MD):

• Manish Sharma, Mayo: Giant vestibular schwannomas.
presented series of giant schwannomas in terms of his evolving experience
venous infarcts: know PF venous anatomy, vein of the cerebellopontine fissure and middle cerebellar peduncle; must save the vcpf as tumor is resected because this is the tumor drainage. Vein of middle cerebellar peduncle is also at risk, venous infarction of cerebellar peduncle.
Anesthesia, IV anesthesia rather than inhalational
Positioning, natural lateral per Janetta
Ventriculostomy through parietal bur hole
Front to back surgical approach
Consider preoperative shunting
Craniotomy, bone removal from petrous ridge down to foraman magnum
Prophylactic cerebellar retraction
Consider two surgical teams
Pseudomeningoceles: “angles of sorrow”
Life- saving or life- taking approach
Santanay’s definition of fanaticism
Giant vest schwannomas: definition of tumor sufficient to produce herniation of tumor or cerebellum through incisura or f magnum
Frequently these patients present with blindness, may be amenable to shunting before surgery with improvement in vision; vision may not improve if surgery before CSF diversion

• Reddy, Chandan: Human Brain- Interface, Decoding Arm Kinematics from EcoG
Closed Loop systems,
Utah electrode arrays placed in the cortex, problems with gliosis. Electrodes have lasted up to 4 years; Mu rhythm is a characteristic drop in EEG power with movement of contrlateral arm. ECoG (surface electrodes) gives access to high frequency power (gamma). Gamma has been used to control 1D and 2D devices.

This study of 6 epilepsy patients at U of Iowa with high frequency recording. Detection of movement activated motor, sensory and frontal sites far from the central sulcus. eCoG may not need reprogramming of parameters at start of each session, algorithms remain stable.

• Emily Knight: DBS for Psychiatric Disorders
Stimulation of n. accumbens in the pig brain, MRI based technology with custom pig head frame, Leksell frame with Medtronic human electrode stimulation, fMRI used to study results of stimulation. Six seconds of stimulation repeated over 12 minutes. Activates prefrontal cortex on fMRI, major depressive disorder and obsessive- compulsive disorders may be amenable to NAc stimulation.

• Michelle Clarke: Primary and Metastatic Tumors of the Spinal Column
Benign lesions, osteochondromas – usually observed, may grow and present as a mass, neurological compromise is rare.

Aggressive benign tumors: osteoblastoma, osteoid osteoma usually involve posterior elements; symptoms usually at night relieved by ASA. these are the same tumor but osteoid osteoma is defined as less than 2 cm. CT shows bony rim surrounding lesion. Block resection will eliminate symptoms. Aggressive osteoblastoma is a variant and may progress to osteosarcoma; en bloc resection would be v. important.

Aneurysmal bone cyst: posterior elements, very vascular; usually in children, expansile cavity with bubbly bone strands. Treatment is controversial: en bloc may be best and lead to least blood loss.

Vertebral hemangiomas are common, involve body not posterior elements. Vertical striations of plain films. Usually no treatment, are amenable to ETOH injection or radiation. Showed a case of large sacral hemangioma with a hollow sacrum treated by local freezing followed by vertebroplasty of the sacrum.

Giant cell tumors, high recurrence rate, en bloc resection is best. Radiation not a good idea because of potential degeneration into malignant tumor.

Eosinophilic tumor of the vertebral body, usually in children and young adults, vert planum is characteristic presentation.

Malignant Spinal Tumors:
Chordoma- sacral and occipital regions, relentless; not amenable to radiation or chemo. Survival depends on local control on first operative attempt. If biopsy performed, eventual resection should include needle biopsy track. Showed a massive surgery for C2 chordoma, results unknown in terms of outcome. Showed sacrectomies for chordoma; usually performed through posterior approach only (planned sacrifice of all sacral roots). Radical excision of sacral chordomas does produce much longer disease free survival.

• Daniels, David: Cranial Dural AV Fistulas (Lanzino)
Surgery remains gold standard for treatment; gamma knife is also alternative but takes up to 3 years to close fistula. Endovascular techniques have developed in the last ten years: transvenus first techniques followed by transarterial techniques. Onyx is a vinyl polymer which sets up more slowly than acrylic cement. Mayo presents 60 cases, 17 treated with Onyx. Presented Cognard Classification System for AV fistulas. Pts. With cortical drainage patterns from Fistulas have a risk of hemorrhage, particularly if varices are present. Hereditary hemophilia may predispose to AVF. Gamma knife had best results in terms of symptomatic improvement, followed closely by surgery and Onyx. Gamma knife did require arterial embolization before radrx and is not suitable for pts with high risk of rupture by classification criteria. Onyx may be emerging as the standard treatment for AVF.

Anyone with PE history has a higher chance of Leiden mutation or similar and consequently a higher chance of AVF.

• Chyatte: Injection Therapy for Spinal Problems
$1850 per injection Workmen’s Comp, FLA, 231% increase 1994- 2001, generally assumed to be effective, no consensus on frequency.

ESI Trials Summary: 40 trials, 10 of 17 found short term benefit, 4/18 showed benefit after 3 months. 3/7 trials showed placebo worked as well as steroids. 2/11 trials showed steroids had benefit over injected saline; 2/7 studies showed that ESI “saved” pts. from surgery.

Particulate steroids contraindicated in cervical injections, may be longer lasting though and have been used in lumbar injections.

Conclusion: Costly, of unproven benefit, no agreement on dose, frequency; no evidence of long term benefit. Howard Chou is an epidemiologist who has studied ESI and advised state governments re: this issue.

• Jeff Beck: EMG and Spinal Radiculopathy
Physician is setting up a spine center for Mayo, he is a physiatrist
22% of patients with cervical radiculopathy also have CTS.
EMG not meaningful for L2- 4 radiculopathies, ant tib not innervated by these segments.
EMG and MRI agree about 75% of the time when weakness is present but only 60% of the time when weakness is not present. Straight leg raising sign more predictive than EMG and nearly as much as MRI.
Summary: EMG is not particularly sensitive or specific nor cost effective for dgx of radiculopathy. Study is only as good as the examiner. EMG no place in radicular problems.

• Bottini, Anthony: Reducing Complications and Costs in Decompressive Surgery fr Spinal Stenosis
Retrospective study of 1000 surgeries for decompression of lumbar spinal stenosis comparing minimally invasive lumbar decompression surgery (MILD) to a similar number of open surgeries for decompression. Complication rates, blood loss, immediate clinical outcome and length of stay significantly lower in the MILD surgery group. Long term outcomes not available.

• Siddiqi, Farhan: Factors Associated with Early Treatment of Ruptured Cerebral Aneurysms in the US
Nationwide database review, early treatment = within 48 hours of aneurysm rupture. SAS 9.1 statistical analysis software. Early treatment was more likely endovascular, more likely female and less likely on the weekend. Recommended transfer of aneurysmal SAH to a teaching hospital on the weekends. No kidding.

• Puffer, Ross: Fate of the Ophthalmic Artery after Flow- Division for Paraclinoid Aneurysms (third year Mayo medical student)
What happens to the opthalmic artery when a pipeline device is deployed? No visual changes in any of 19 patients, artery occluded in 4, sluggish flow in 2. There is a 25% occlusion rate with no apparent consequences because ophthalmic artery has good collateral flow. These results should not be extrapolated to end vessels for that reason.

• Lanzino, Guiseppe: Pipeline Embolization of Complex IntracranialAneurysms: Hype or Reality?
Now FDA approved for use in proximal paraclinoid internal carotid artery aneurysms. 30 ICA aneurysms in series of 28 patients. Pipeline is a flow diverter device which results in delayed thrombosis of aneurysms with angiographic normalization over several months; for that reason, not indicated in the treatment of ruptured aneurysms. Complete obliteration in 70% at 6 months and 92% at one year. No permanent complications. Limitations: early hemorrhage after Pipeline placement. Sometimes partial coiling of the aneurysm at the time of application might be helpful. Long term patency not established; need for and length of antiplatelet therapy not clear. Probably not for vertebrobasilar aneurysms.

• Hassan, Ameer: Rate and Prognosis of Patients Failing Local Anesthesia and Requiring Emergent Intra-Procedural Intubation in NeuroEndovascular Procedures.
1.7% of planned local cases were converted to general anesthesia. Occurred most in treatment of ruptured and unruptured aneurysms.

• Vasquez, Ciro: A Case of Obstructive Hydrocephalus following Deep Brain Stimulaton for Parkinson’s Disease.
Subthalamic nucleus target, 1- 4% chance of hemorrhage, 1- 3% per electrode placement. Hypertension, size of electrode, multiple passages and transventricular passage increase the risk of hemorrhage. Reported patient hemorrhaged more than 6 hours after placement; small amount of aqueductal blood producing obstructive hydrocephalus. Ventric placed and drained for three days, removed, hydrocephalus resolved.

• Kainth, Darapreet: Epidemiological and Clinical Features of Moyamoya Disease in the United States.
ICD- 9 review of hospitalization for Moyamoya disease across the US. Bimodal age distribution with peaks in 1st and 4th decades. Hemorrhagic strokes more common in 70’s and 80’s. Majority of patients are Caucasians? More women than men, children have ischemic strokes, adults have hemorrhage more often; lower rates of hemorrhage for Moyamoya in the US than in Japan.

• Farhan, Siddiqi: Occurrence and Prognostic Significance of Pseudodissection Phenomenon Associated with Acute Distal Internal Carotid Artery Occlusion.
Classical angiographic appearance is flame shaped occlusion with maybe a string sign. Some patients show what appears to be an acute dissection which may lead to non helpful surgery. Happens most often with acute carotid occlusion at the petro- cavernous segment of the vessel.

• Link, Michael: Hemifacial Spasm, A Single Surgeon’s Experience
Involuntary, rhythmic, unilateral, usually begins in the peri- orbital musculature and spreads. Try neuromodulating agents but usually don’t work. Botox injections are helpful but difficult. One report of treatment with radio surgery with some success in a small Italian series reported last year. Link has operated on 38 patients for hemifacial spasm. Infrafloccular approach to look for arterial compression. Showed a case with compression by vert, AIC and PICA all on the same facial nerve. Recurrence rate in this series is 5%. Series results: 71% resolved, 24% improved and 5% failure rate.
Validated scale (HFS) for measuring patient’s outcome. Should you “rough up” the facial nerve before closing to improve the immediate outcome?

• Lee, Kendall: Neuromodulation Surgery for Pain and Psychiatric Indications
Emerging treatments with DBS techniques. 19 surgeries at Mayo for somatosensory stimulation for pain relief. Stimulation testing at time of implantation frequently causes seizures, decreasing stim parameters usually resolves seizure problems. May be a treatment for anesthesia dolorous (actually the patients who respond best to this stim technique).

DBS for chronic pain: N. accumbens and periventricular gray stimulation appears to decrease pain. Stimulation of the N accumbens produces involuntary smiling.

Tourette’s Syndrome TS: Bilateral thalamic DBS may be helpful in TS. (tic, echolalia, coprolalia, anxiety, OCD, ADHD). 4 patients treated at Mayo for TS with DBS.

They have not treated OCD or depression with DBS but reportedly plan to in the near future. Now FDA approved for OCD as humane use clause.

• Saturday Evening Dinner: James Bean’s Talk

Tides of Change: The Economic Evolution of Neurosurgery Practice

Same talk as at MINS, he loves talking taxes.

Innovator’s Prescription or Who Killed Health Care?

• Sunday Program

• Resident’s Award: Lanzino, Chyatte, Mullan

Siddiqi pseudo dissection paper, first runner up
Daniels winner

Treasurer’s report: 36 k, 4 k for meeting; 8500 from educational grants
33 paying members, $150 membership
Meeting registration was $200

Election: Matt Hunt is new Sec/Treasurer

Ann Parr chosen as the CSNS representative for the Society.

Society’s Academic meeting will be held in Redwing again next year.