James L. Stone

Use of Halifax interlaminar clamps for posterior C1-C2 arthrodesis

Eight patients with atlantoaxial instability secondary to trauma or rheumatoid arthritis were treated with posterior C1-C2 arthrodesis using the Halifax interlaminar clamp and autogenous bone graft or methylmethacrylate. Thus far, with an average follow-up of 6 months, satisfactory stability has been achieved with no instrument failure.

Effects of Incremental Ketamine Hydrochloride Doses on Motor Evoked Potentials (meps) Following Transcranial Magnetic Stimulation: A Primate Study

Summary the cumulative dose effect of ketamine hydrochloride (KH) on transcranial magnetic-induced motor evoked potentials (MEPs) was examined in monkeys. Electromyographic (EMG) responses were recorded from the contralateral abductor pollicis brevis (APB) and abductor hallucis (AH) muscles. MEP brain stimulation threshold, latency, and amplitude values were studied. After obtaining baseline recordings, increments of KH (5 mg/kg every 15–20 min) were given i.v. (50 mg/kg total dose). MEPs were repeatedly recorded following KH injections. No loss of potentials was encountered in any animal. However, KH induced significant MEP latency delay in doses ≥35–40 mg/kg and amplitude depression in doses ≥15–20 mg/kg (p < 0.01). Under various KH doses, the amplitude depression ranged from 13.6 to 45.5% for APB and 57.3 to 82% for AH compared to the control values. The MEP latency prolongation ranged from 3.5 to 18% for APB and 4.2 to 13.1% for AH. The stimulation threshold rise ranged from 6.7 to 14.7% for APB and 7 to 17.9% for AH. Statistical correlation was closest between cumulative KH doses and MEP latency prolongation. We conclude that, in the primate model, reliable MEP recording is feasible under deep KH anesthesia. However, awareness of drug-induced response alterations is essential during interpretation of intraoperative MEP changes. Further investigation is warranted regarding the specific dose effect in humans and safety of magnetic stimulation.

Outcome of laminectomy for civilian gunshot injuries of the terminal spinal cord and cauda equina: review of 88 cases.

Case records of 88 patients with low-velocity gunshot injuries of the terminal spinal cord and cauda equina treated by laminectomy at Cook County Hospital between 1969 and 1987 were reviewed. Sixty-one patients were operated upon within 72 hours of injury, 29 of whom (47.5%) experienced neurological improvement or pain relief. Twenty-seven patients were operated upon at a later time for associated injuries, 13 of whom (48.1%) experienced neurological improvement or pain relief. When laminectomy was delayed for more than 2 weeks, either arachnoid adhesions (15%) or occult abscesses (17%) were observed. From this review as well as from the literature, it appears that the timing of laminectomy for gunshot injuries of the thoracolumbar and lumbosacral spine is not essential to neurological recovery. It appears, however, that adequate debridement of these injuries, performed as soon as the patient is stable from any associated injuries, may help to mitigate the late sequelae of arachnoiditis, infection, and pain syndromes in the lower extremities.

Intradural thoracic disc herniation

Study Design. Patients with intradural herniation of an intervertebral disc were identified and managed surgically. Objectives. Illustrative cases of patients with intradural herniated discs at the mid‐thoracic level are presented, the literature is reviewed, and the management of these patients is discussed. Summary of Background Data. Intradural herniation of an intervertebral disc is rare and most common at the lumbar level, but isolated cases have been reported at other levels. Cases reports of this entity have been published, but the surgical details have not been adequately addressed. Methods. In this report, two patients with calcified intradural herniated discs at the mid‐thoracic level are presented. Results. Both patients had progressive paraparesis and had calcified disc material in the mid‐thoracic canal. Both were treated successfully with a posterolateral extracavitary costotransversectomy and hemilaminotomy using intraoperative ultrasound and somatosensory‐evoked potential monitoring. Conclusions. This entity should be suspected when a calcified disc within the spinal canal is being treated. The optimal exposure is a posterolateral extracavitary costotransversectomy with a hemilaminotomy. Alternative approaches to a typical thoracic disc would be problematic in managing these patients. [Key words: intradural disc herniation, intravertebral disc herniation, spinal cord compression, thoracic disc] Spine 1994;19: 1281–1284

SPINAL CORD DECOMPRESSION VIA A MODIFIED COSTOTRANSVERSECTOMY APPROACH COMBINED WITH POSTERIOR INSTRUMENTATION FOR MANAGEMENT OF METASTATIC NEOPLASMS OF THE THORACIC SPINE

Fifteen patients with thoracic spinal cord compression from metastatic neoplastic processes were managed by spinal canal decompression via a modified costotransversectomy approach. Ten of the patients also underwent sequential posterior stabilization with Luque or Harrington instrumentation based upon proximity of the lesion to the thoracolumbar junction, prognosis for regaining or maintaining ambulatory ability, and additional spinal stability considerations. A modified lateral decubitus position with the scapula falling away from the side of exposure was used for T1-5 segment lesions, and a prone position was used for the (T-6)-(T-12) segment. Adequate decompression of the spinal canal was achieved in all cases. All patients who were ambulating preoperatively maintained ambulatory ability, and pain and/or further neurological improvement as well occurred in 75%.

Rupture of a giant carotid aneurysm after extracranial-to-intracranial bypass surgery.

We report a case of a fatal rupture of a previously unruptured giant aneurysm of the bifurcation of the internal carotid artery (ICA), which occurred after an extracranial-intracranial (EC-IC) bypass and the partial occlusion of the ICA. Interim angiography showed retrograde filling of the proximal middle cerebral artery to the aneurysm. There have been four previously reported cases of giant aneurysms rupturing after treatment with an EC-IC bypass and carotid ligation, and it appears likely that a change in pressure/flow dynamics produced by the bypass may have been the cause. The technique of carotid ligation with an EC-IC bypass is used frequently to treat unclippable intracranial aneurysms, and the resulting hemodynamic changes need to be considered carefully to prevent this type of complication. To minimize hemodynamic stress on the aneurysm, we suggest that 1) the bypass caliber should be as small as possible consistent with sufficient cerebral blood flow after ICA occlusion, and 2) complete ICA occlusion should be performed as soon as possible after the bypass.

Episodic dyscontrol disorder and paroxysmal EEG abnormalities: Successful treatment with carbamazepine

Rhythmic midtemporal discharges (RMTD or psychomotor variant) and 6/set spike and wave complexes (6SW) are considered to be controversial electroencephalic (EEG) patterns because of a variable association with clinical seizures and nonspecific psychological features (Gibb et al. 1963; Garvin 1968; Thomas and Klass 1968). Many electroencephalographers consider these uncommon patterns to be normal variants (Maulsby 1979). However, numerous studies have demonstrated a positive correlation between psychiatric symptomatology and these EEG findings (Small et al. 1968; Milstein and Small 1971; Olson et al. 1971; Hughes and Hermann 1984). This article describes a patient with EEG findings of both RMTD and 6SW: psychiatric symptomatology lessened and paroxysmal EEG abnormalities abated with carbamazepine treatment.

Brainstem auditory evoked potentials - A review and modified studies in healthy subjects

Summary: The authors review the brainstem auditory evoked potential (BAEP), and present studies on 40 healthy subjects. In addition to the conventional click evoked BAEP, three modified BAEP examinations were performed. The modified BAEP tests include a 1,000 Hz tone-burst BAEP, and more rapid rate binaural click and 1,000 Hz tone-burst BAEPs–each of the last two studies performed at four diminishing moderate intensities. In addition to the usual parameters, the authors examined the Wave V to Vn interpeak latency, and stimulus intensity versus Wave V latency and amplitude functions in the rapid rate binaural studies. Studies were also repeated on healthy subjects in a dependant head position in an attempt to increase intracranial pressure. Discussion centers on the BAEP, its current utility in medicine, unique neurophysiology, and literature support that the above modifications could increase the practicality of the test in patients at risk with intracranial lesions and perhaps improve the feasibility for real-time continuous or frequent monitoring in the future.

Cavernous angioma of the upper cervical spinal cord : a case report

Study Design The treatment of a patient with progressive neurologic deficit secondary to a cavernous angioma located in the dorsal midline of the upper-most cervical spinal cord was described. Objectives An illustrative case of a patient with an exophytic cavernous angioma of the cervical spinal cord near the cervicomedullary junction was presented, the literature reviewed, and the treatment of these patients discussed. Summary of Background Data Cavernous angiomas of the spinal cord were rarely seen, and only more recently appreciated with the advent of MRI scanning. These lesions were usually intramedullary in location. Intradural extramedullary cavernous angiomas, or intramedullary lesions with exophytic extramedullary extension, were particularly rare and usually occurred at the cauda equina. Methods The surgical treatment of a patient with an exophytic cavernous angioma of the upper carvical spinal cord was presented. Results This patient underwent surgery after a hemorrhage that occurred after the patient was treated conservatively for sevaral years. The entire lesion was resected with standard microsurgical technique, and the neurologic symptoms subsequently resolved. Conclusions This entity should be suspected in the differential diagnosis of patients with progressive and step-wise deterloration of spinal cord function. Although these patients can be treated conservatively, those with progressive neurologic deficits should undergo microsurgical resection to avert subsequent lesion enlargement or repeated hemorrhage.

Historical characterization of trigeminal neuralgia

TRIGEMINAL NEURALGIA IS a well known clinical entity characterized by agonizing, paroxysmal, and lancinating facial pain, often triggered by movements of the mouth or eating. Historical reviews of facial pain have attempted to describe this severe pain over the past 2.5 millennia. The ancient Greek physicians Hippocrates, Aretaeus, and Galen, described kephalalgias, but their accounts were vague and did not clearly correspond with what we now term trigeminal neuralgia. The first adequate description of trigeminal neuralgia was given in 1671, followed by a fuller description by physician John Locke in 1677. André described the convulsive-like condition in 1756, and named it tic douloureux; in 1773, Fothergill described it as “a painful affection of the face;” and in 1779, John Hunter more clearly characterized the entity as a form of “nervous disorder” with reference to pain of the teeth, gums, or tongue where the disease “does not reside.” One hundred fifty years later, the neurological surgeon Walter Dandy equated neurovascular compression of the trigeminal nerve with trigeminal neuralgia.