Operative microphotography: a Malis legacy.

An account of the methods and equipment used by Dr. Malis for the development of operative microphotography is presented. Attention to the critical evaluation of technology became part of the legacy provided to those he trained. Current microphotographic innovations are described.

The prone-oblique surgical position.

The prone-oblique surgical position as introduced and used by Dr. Malis at Mount Sinai Hospital is presented. The advantages of this position over the prone and knee-chest positions are noted. Recommendations for the safe use of the prone-oblique position are made.

Anterior-approach cervical diskectomy under the operating microscope.

Since Cloward's description of it in 1958, the anterior approach to the cervical spine for excision of degenerated cervical disk causing radiculopathy and myelopathy and for excision of secondary bony spurs has become relatively standard for most spine surgeons. The procedure is easy to perform in trained hands, is a low-risk surgical operation, and has gratifying results provided patients are well selected. Many surgeons use an operating microscope while doing the procedure. The obvious advantages of the microscope are better magnification, enhanced stereoscopic visibility in a small field, better visualization of the anatomic structures, and added safety. The focused lighting is valuable in achieving satisfactory decompression of the nerve root and the spinal cord. The microscope is also a valuable teaching tool at the time of surgery. Our technique for the procedure employing the microscope is described and stereoscopic photographs taken during surgery are presented.

Vagal elicitation of respiratory-type and other unit responses in striopallidum of squirrel monkeys.

The putamen and globus pallidus were explored in awake, sitting squirrel monkeys while testing the effects of vagal volleys on the activity of isolated units. Triple shocks were applied to the left cervical vagus nerve every 4 sec. Special computer methods were developed for recording and analyzing data. As a control for adventitious extravagal somatic stimulation, units responsive to vagal volleys were also tested during shock-induced facial and cervical twitches. Under the given conditions, 30% of the units were responsive only to vagal volleys. The ratio of initially excited to initially inhibited units was about 2:3. The response latencies ranged from 6 to 200 msec, values indicative of both rapidly and slowly conducting, afferent pathways. The entrainment of respiration by vagal volleys revealed that 6% of the tested units gave a periodic discharge that appeared to correlate with the respiratory rhythm. This last result compares to that described and discussed in the following companion paper on basal limbic structures.

Vagal elicitation of respiratory-type and other unit responses in basal limbic structures of squirrel monkeys.

Basal limbic structures (insula, amygdala, hippocampus and surrounding areas) were explored for unit responses to vagal volleys in awake, sitting, squirrel monkeys. Triple shocks were applied every 4 sec to the left cervical vagus nerve. As a control for adventitious activation by extravagal somatic afferents, units responsive to vagal volleys were also tested during shock-induced facial and cervical twitches. Under the given conditions, 16% of a population of more than 200 limbic units responded only to vagal volleys. The ratio of initially excited to initially inhibited units was about 2:3. The response latencies were indicative of both rapidly and slowly conducting, afferent pathways. The entrainment of respiration by vagal volleys revealed that 6% of the tested units discharged with a periodicity commensurate with the respiratory rhythm. Such respiratory units were found in the anterior amygdala, insula and hippocampus. In the case of the hippocampus it can be concluded that the discharge of respiratory-type units is not dependent on olfactory inputs. In the amygdala, the highest percentage of responsive units was found in the central nucleus; none were of a respiratory-type. The particular interest of the respiratory-type units found in this and the preceding study is discussed.

Computer assisted unit data acquistion/reduction.

A computer system for unit data acquisition and reduction (CAUDAR) is presented. This system digitally processes uninterrupted, continuous unit data with attention to waveform detail. Several units in a multiunit field are recognized by evaluation of spike waveform and amplitude. High-speed computer graphics provides almost instantaneous figures of good quality for illustration. The system affords a great economy of the user's time because the computer performs all data processing.