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Biomedical subjects

S J Larson

Publications and source records attributed to S J Larson.

At least 73 records · Page 4Linked to original sources
PubMed1980

Stereotactic aspiration of deep cerebral abscesses after CT-directed labeling.

Multiple, deep cerebral abscesses were treated in 2 patients by stereotactic aspiration after CT-guided needle labeling of single cavities. Separation of labeling from stereotactic manipulations avoids CT artifact generated by standard frame components; the technique will, therefore, accommodate most stereotactic instruments in current use. Alignment of CT and stereotactic coordinates hinged upon coidentification of the Pantopaque-labeled cavity on CT scans and on routine skull films with the stereotactic frame in place. Proximity of the label to targets eliminated the need for special head fixation or complex baseline correction.

Adult↗
PubMed1979

Spinal cord evaluation by cortical evoked responses.

In ten monkeys, selective segmental lesions of the dorsal columns at the upper thoracic and middle cervical levels resulted in almost total attenuation of the cortical evoked potential responses to peripheral nerve stimulation. Conversely isolated segmental dorsal column preservation showed intact transmission of the evoked responses at rostral spinal cord, nucleus ventralis posterior lateralis, and cortical levels. Responses recorded from the intralaminar thalamic nuclei in the region of nucleus centrum medianum were unaffected by dorsal column ablation, but were markedly attenuated following bilateral ventral column ablation.

Animals↗
PubMed1979

Gas myelography in spinal cord injury.

Using polytomographic techniques, gas myelography was performed in 162 patients with post-traumatic neurologic deficit. The type, extent, and location of lesions were easily demonstrated, allowing adequate preoperative surgical planning. In cases in which expected neurologic improvement did not follow surgery, postoperative myelography provided information so that remedial measures could be taken. No neurologic deterioration was noted in any of the patients and furthermore, arachnoiditis, which may accompany positive contrast myelography, has not been detected in any of the patients in the series reported.

Humans↗
PubMed1978

Early somatosensory evoked potentials.

The early somatosensory evoked potential secondary to median nerve stimulation in the human had an onset latency of 9--12 msec when recorded from scalp electrodes at vertex-to-mastoid, vertex-to-inion or at the base of the skull. Similar latencies were observed from responses recorded over the cervical dorsal columns during neurologic surgery. A latency difference of 1.5 msec was observed between the early response and the responses recorded from the junction of medial lemniscus and nucleus ventralis posterior lateralis of the thalamus during human stereotaxic surgery. Cervical cord transections and transection at the midpontine levels of the monkey showed that the evoked potential was due to generators between these levels. Depth recording of the monkey indicate that the early evoked potential originates in the region of dorsal column nuclei, while the later components are secondary to generators in cerebral cortex.

Animals↗
PubMed1978

Arachnoiditis from experimental myelography with aqueous contrast media.

Myelography was performed on 80 monkeys to study postmyelographic arachnoiditis. Metrizamide myelography caused arachnoiditis when high concentrations were used, but not with the usual clinical concentrations. Arachnoiditis resulted after myelography with meglumine iocarmate; however, the risk of arachnoiditis was reduced by diluting the contrast medium. Prophylactic intrathecal methylprednisolone was not effective in preventing arachnoiditis. Blood in the cerebrospinal fluid did not affect the degree of arachnoiditis.

Animals↗
PubMed1978

Ineffectiveness of prophylactic intrathecal methylprednisolone in myelography with aqueous media.

The effectiveness of prophylactic intrathecal methylprednisone (MP) in preventing arachnoiditis from iocarmate myelography was studied. Monkeys were injected intrathecally with locarmate, MP, or a combination of the two. Twelve weeks later the severity of arachnoiditis was determined in each animal. There was no significant prophylactic effect of intrathecal MP on arachnoiditis from locarmate. Some arachnoiditis was found in control animals treated with MP alone.

Animals↗
PubMed1978

Comparison of arachnoiditis produced by meglumine iocarmate and metrizamide myelography in an animal model.

Myelography in monkeys was performed with either meglumine iocarmate or metrizamide. The severity of resultant arachnoiditis in each animal 12 weeks later was evaluated by repeat myelography and by histologic study of the arachnoid. Three of the four animals examined with meglumine iocarmate had severe arachnoiditis; none of the four animals examined with metrizamide had as severe changes. The difference between the two groups was statistically significant (P less than .05).

Animals↗
PubMed1978

Spinal evoked potentials in the primate: neural substrate.

Summated responses evoked by peripheral nerve stimulation were recorded from electrodes located in the epidural and subdural spaces anterior and posterior to the monkey spinal cord. Segmental microsurgical resection of the dorsal columns both at the thoracic and cervical levels resulted in total obliteration of the response recorded rostral to these lesions. Isolated segmental dorsal column preservation did not significantly alter response latency or wave form recorded at the rostral electrodes. Bilateral cervical dorsolateral column resection also resulted in no discernible alterations of these responses. These data indicate that spinal evoked potentials recorded from levels rostral to their root entry zones arise almost exclusively from the dorsal columns.

Animals↗
PubMed1978

Traumatic bilateral carotid-cavernous sinus fistulas with progressive unilateral enlargement.

The authors present a patient with traumatic bilateral carotid-cavernous sinus fistulas associated with fracture of the sella turcica. Repeat angiography ten days after admission revealed that the left fistula had enlarged and was shunting the entire output of the left carotid artery and a portion of the output of the basilar artery. A muscle embolization procedure was sucessfully performed on the left side but was complicated by hemorrhage from the left cavernous sinus prior to closure. Problems associated with the enlargement of carotid-cavernous fistulas are discussed.

Adult↗
PubMed1977

Experimental production of arachnoiditis with water-soluble myelographic media.

After myelography with either metrizamide (300mg l/ml) or meglumine iocarmate (280 mg l/ml), mild to severe arachnoid fibrosis was demonstrated radiographically and histologically in primates. Intrathecal injections of metrizamide (170 mg l/ml) or autologous cerebrospinal fluid produced less arachnoiditis. The risk of arachnoiditis is probably minimized by the use of reduced volumes and concentrations of water-soluble media. Controlled studies of arachnoiditis following myelography are probably more reliable in the primate model than in other experimental animals.

Animals↗