Direct brainstem somatosensory evoked potentials for cavernous malformations

OBJECTIVE Brainstem cavernous malformations (CMs) often require resection due to their aggressive natural history causing hemorrhage and progressive neurological deficits. The authors report a novel intraoperative neuromonitoring technique of direct brainstem somatosensory evoked potentials (SSEPs) for functional mapping intended to help guide surgery and subsequently prevent and minimize postoperative sensory deficits. METHODS Between 2013 and 2019 at the Stanford University Hospital, intraoperative direct brainstem stimulation of primary somatosensory pathways was attempted in 11 patients with CMs. Stimulation identified nucleus fasciculus, nucleus cuneatus, medial lemniscus, or safe corridors for incisions. SSEPs were recorded from standard scalp subdermal electrodes. Stimulation intensities required to evoke potentials ranged from 0.3 to 3.0 mA or V. RESULTS There were a total of 1 midbrain, 6 pontine, and 4 medullary CMs—all with surrounding hemorrhage. In 7/11 cases, brainstem SSEPs were recorded and reproducible. In cases 1 and 11, peripheral median nerve and posterior tibial nerve stimulations did not produce reliable SSEPs but direct brainstem stimulation did. In 4/11 cases, stimulation around the areas of hemosiderin did not evoke reliable SSEPs. The direct brainstem SSEP technique allowed the surgeon to find safe corridors to incise the brainstem and resect the lesions. CONCLUSIONS Direct stimulation of brainstem sensory structures with successful recording of scalp SSEPs is feasible at low stimulation intensities. This innovative technique can help the neurosurgeon clarify distorted anatomy, identify safer incision sites from which to evacuate clots and CMs, and may help reduce postoperative neurological deficits. The technique needs further refinement, but could potentially be useful to map other brainstem lesions.

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Localization of Stereotactic Targets by Microrecording of Thalamic Somatosensory Evoked Potentials

Neurosurgery ◽

10.1227/00006123-199102000-00008 ◽

1991 ◽

Vol 28 (2) ◽

pp. 223-230 ◽

Cited By ~ 17

Author(s):

Fumio Shima ◽

Takato Morioka ◽

Shozo Tobimatsu ◽

Omiros Kavaklis ◽

Motohiro Kato ◽

...

Keyword(s):

Evoked Potentials ◽

Median Nerve ◽

Somatosensory Evoked Potentials ◽

Practical Method ◽

The Other ◽

Basal Region ◽

Thalamic Nuclei ◽

Median Nerve Stimulation ◽

Lower Amplitude ◽

Stimulation Of

Abstract To improve the localization of stereotactic targets, somatosensory evoked potentials (SEPs) were recorded from the thalamus and subthalamic area using a specially designed semimicroelectrode in 61 patients and a conventional “macroclectrode” in 17 patients. By means of the semimicroelectrode, median nerve stimulation evoked two distinct SEPs, consisting of a diphasic wave with a huge positivity restricted to the nucleus ventrocaudalis (Vc) and a triphasic wave of lower amplitude with a major negativity in the ventral part of the nucleus ventrointermedius (Vim) and nucleus ventrooralis posterior (Vop) as well as the subthalamic lemniscal pathway. The Vim-Vc junction could thus be clearly delineated by an abrupt transition of SEPs from one type to the other with a precision of 1 mm. The parvicellular part of the Vc (Vcpc). situated in its basal region, was distinguishable from the Vc proper by a significant reduction of the positivity elicited by stimulation of the median nerve and by a rapid growth of a diphasic SEPs to stimulation of the posterior tibial nerve. In the other thalamic nuclei, stimulation of the median nerve elicited triphasic SEPs of a very small amplitude, suggesting a volume conduction current from the lemniscal pathway. With the macroclectrode, the positivity in the Vc was sensitive to electrode manipulation and the thalamic nuclei could not be distinctly outlined. SEP monitoring using the semimicroelectrode significantly improved the precision of target localization, which allowed minimizing of the volume of the therapeutic lesion without losing surgical effectiveness, while avoiding complications associated with increased penetration of the coagulating electrode. It is suggested that recording serial thalamic SEPs with the semimicroelectrode is a practical method to refine stereotactic targets in the thalamus.

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Comparison of scalp distribution of short latency somatosensory evoked potentials (SSEPs) to stimulation of different nerves in the lower extremity

Electroencephalography and Clinical Neurophysiology/Evoked Potentials Section ◽

10.1016/0168-5597(88)90046-9 ◽

1988 ◽

Vol 71 (6) ◽

pp. 422-428 ◽

Cited By ~ 32

Author(s):

Luciana Pelosi ◽

Joan B. Cracco ◽

Roger Q. Cracco ◽

Nasser F. Hassan

Keyword(s):

Lower Extremity ◽

Evoked Potentials ◽

Somatosensory Evoked Potentials ◽

Short Latency ◽

Scalp Distribution ◽

Stimulation Of

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BOLD fMRI and somatosensory evoked potentials are well correlated over a broad range of frequency content of somatosensory stimulation of the rat forepaw

Brain Research ◽

10.1016/j.brainres.2007.11.036 ◽

2008 ◽

Vol 1195 ◽

pp. 67-76 ◽

Cited By ~ 22

Author(s):

Artem G. Goloshevsky ◽

Afonso C. Silva ◽

Stephen J. Dodd ◽

Alan P. Koretsky

Keyword(s):

Evoked Potentials ◽

Somatosensory Evoked Potentials ◽

Frequency Content ◽

Somatosensory Stimulation ◽

Bold Fmri ◽

Stimulation Of

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Human proprioceptive adaptations during states of height-induced fear and anxiety

Journal of Neurophysiology ◽

10.1152/jn.01030.2010 ◽

2011 ◽

Vol 106 (6) ◽

pp. 3082-3090 ◽

Cited By ~ 30

Author(s):

Justin R. Davis ◽

Brian C. Horslen ◽

Kei Nishikawa ◽

Katie Fukushima ◽

Romeo Chua ◽

...

Keyword(s):

Evoked Potentials ◽

Somatosensory Cortex ◽

Somatosensory Evoked Potentials ◽

Emotional Experience ◽

Afferent Feedback ◽

Triceps Surae ◽

Feedback Gain ◽

Postural Threat ◽

Fear And Anxiety ◽

Stimulation Of

Clinical and experimental research has demonstrated that the emotional experience of fear and anxiety impairs postural stability in humans. The current study investigated whether changes in fear and anxiety can also modulate spinal stretch reflexes and the gain of afferent inputs to the primary somatosensory cortex. To do so, two separate experiments were performed on two separate groups of participants while they stood under conditions of low and high postural threat. In experiment 1, the proprioceptive system was probed using phasic mechanical stimulation of the Achilles tendon while simultaneously recording the ensuing tendon reflexes in the soleus muscle and cortical-evoked potentials over the somatosensory cortex during low and high threat conditions. In experiment 2, phasic electrical stimulation of the tibial nerve was used to examine the effect of postural threat on somatosensory evoked potentials. Results from experiment 1 demonstrated that soleus tendon reflex excitability was facilitated during states of height-induced fear and anxiety while the magnitude of the tendon-tap-evoked cortical potential was not significantly different between threat conditions. Results from experiment 2 demonstrated that the amplitudes of somatosensory-evoked potentials were also unchanged between threat conditions. The results support the hypothesis that muscle spindle sensitivity in the triceps surae muscles may be facilitated when humans stand under conditions of elevated postural threat, although the presumed increase in spindle sensitivity does not result in higher afferent feedback gain at the level of the somatosensory cortex.

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