Biomedical subjects

H D Jho

Publications and source records attributed to H D Jho.

At least 55 records · Page 3Linked to original sources

PubMed1995

Microvascular decompression for spasmodic torticollis.

Twenty patients with spasmodic torticollis (ST) were treated by microvascular decompression (MVD) of the spinal accessory nerves, the upper cervical nerve roots and the brainstem. Thirteen were female and seven male. Median age was 47 years (range 39 to 70 years). Median duration of symptoms was 5 years (range 4 months to 17 years). Ten had right horizontal; nine, left horizontal; and one, retrocollis ST. Twenty-two operations were performed on twenty patients, suboccipital craniectomy and C1 laminectomy in 18 and retromastoid craniectomy in 4 operations. The most common compressing blood vessels were the vertebral artery and/or the posterior inferior cerebellar artery. No nerve section was performed. Three patients died of unrelated conditions, 3, 5 1/2, and 6 years postoperatively, respectively. Minimum follow-up period in the rest of the cases is 5 years (range 5 to 10 years). Thirteen (65%) were cured, four (20%) improved with minimal spasm, one (5%) improved with moderate spasm, and two (10%) improved minimally or unchanged. In most cases the cure or improvement was noticed gradually over 6 months to two years following the operation. There was no operative mortality. Postoperative morbidities included transient cerebrospinal fluid leakage through the surgical incision in one case and an apparent multiple small vessel stroke involving periventricular white matter in one reoperation case with full recovery. MVD for ST is a nondestructive benign procedure with high probability of cure or significant improvement.

Accessory Nerve↗

PubMed1995

Microvascular decompression for glossopharyngeal neuralgia.

Glossopharyngeal neuralgia is an uncommon cause of facial pain with a relative frequency of 0.2 to 1.3% when compared with trigeminal neuralgia. It is characterized by intermittent, lancinating pain involving the posterior tongue and pharynx, often with radiation to deep ear structures. Since its first description in 1910 by Weisenburg, a variety of destructive procedures have been performed to provide relief in patients whose pain was refractory to medical treatment. These procedures all necessitated the sacrifice of the glossopharyngeal nerve and, in most cases, also involved the destruction of at least part of the vagus nerve as well. In 1977, Laha and Jannetta reported good results in four patients who underwent microvascular decompression of the glossopharyngeal and vagus nerves for glossopharyngeal neuralgia. Since 1971, 40 patients have undergone microvascular decompression of the glossopharyngeal and vagus nerves for treatment of typical glossopharyngeal neuralgia. This procedure provided excellent immediate results (complete or > 95% relief of pain) in 79%, with an additional 10% having a substantial (> 50%) reduction in pain. Long-term follow-up (mean, 48 mo; range, 6-170 mo) reveals excellent results (complete or > 95% reduction in pain without any medication) in 76% of the patients and substantial improvement in an additional 16%. There were two deaths at surgery (5%) both occurring early in the series as the result of hemodynamic lability causing intracranial hemorrhage. Three patients (8%) suffered permanent 9th nerve palsy. (ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1995

Contribution from crossed and uncrossed brainstem structures to the brainstem auditory evoked potentials: a study in humans.

The neural generators of the brainstem auditory evoked potentials (BAEPs) in humans are not completely known. Attempts to identify the anatomical location of the neural generators of the human BAEP based on the results of studies in animals commonly used in auditory experimentation have been difficult because of the considerable anatomical differences between the ascending auditory pathways in humans and animals. The authors of this study compared recordings obtained from different locations on the lateral side of the brainstem in six patients undergoing microvascular decompression surgery for a cranial nerve disorder affecting the fifth cranial nerve (i.e., trigeminal neuralgia). Ipsilateral click stimulation evoked prominent responses from the caudal aspect of the pons up to the junction between the pons and the midbrain, but all components of the responses with latencies shorter than 8 msec had smaller amplitudes when recorded at more rostral locations. Components with latencies in the range of peak V elicited by contralateral click stimulation had their largest amplitudes when recorded from the lateral brainstem at the level of the fourth cranial nerve (thus, close to the inferior colliculus). Earlier components of the contralateral responses (latencies in the range of the latency of peak III) had their largest amplitudes when recorded from the caudal lateral brainstem. The results of this study indicate that the part of the uncrossed auditory pathway that is located rostral to the cochlear nucleus contributes little to the farfield potentials (i.e., BAEP), and it is doubtful whether the contralateral response that can be recorded at the level of the cochlear nucleus contributes noticeably to the BAEP.

Acoustic Stimulation↗

PubMed1995

Microvascular decompression for hemifacial spasm.

The authors report the results of 782 microvascular decompression procedures for hemifacial spasm in 703 patients (705 sides), with follow-up study from 1 to 20 years (mean 8 years). Of 648 patients who had not undergone prior intracranial procedures for hemifacial spasm, 65% were women; their mean age was 52 years, and the mean preoperative duration of symptoms was 7 years. The onset of symptoms was typical in 92% and atypical in 8%. An additional 57 patients who had undergone prior microvascular decompression elsewhere were analyzed as a separate group. Patients were followed prospectively with annual questionnaires. Kaplan-Meier methods showed that among patients without prior microvascular decompression elsewhere, 84% had excellent results and 7% had partial success 10 years postoperatively. Subgroup analyses (Cox proportional hazards model) showed that men had better results than women, and patients with typical onset of symptoms had better results than those with atypical onset. Nearly all failures occurred within 24 months of operation; 9% of patients underwent reoperation for recurrent symptoms. Second microvascular decompression procedures were less successful, whether the first procedure was performed at Presbyterian-University Hospital or elsewhere, unless the procedure was performed within 30 days after the first microvascular decompression. Patient age, side and preoperative duration of symptoms, history of Bell's palsy, preoperative presence of facial weakness or synkinesis, and implant material used had no influence on postoperative results. Complications after the first microvascular decompression for hemifacial spasm included ipsilateral deaf ear in 2.6% and ipsilateral permanent, severe facial weakness in 0.9% of patients. Complications were more frequent in reoperated patients. In all, one operative death (0.1%) and two brainstem infarctions (0.3%) occurred. Microvascular decompression is a safe and definitive treatment for hemifacial spasm with proven long-term efficacy.

Adolescent↗

PubMed1995

Chronic abdominal pain caused by thoracic disc herniation.

A patient with 7 yr of severe disabling chronic epigastric abdominal pain attributed to chronic pancreatitis was seen in consultation before a 95% pancreatectomy for pain control. Previous attempts to identify and treat the pain lead to extensive radiographic, pharmacological, endoscopic, and surgical interventions, including a Roux-en-Y pancreaticojejunostomy. Pain control was poor despite implantation of a continuous intrathecal morphine infusion pump. A focused physical examination, however, raised the suspicion of thoracic disc disease, which was confirmed after myelogram with computed tomography. Disruption of the T7-T8 disc with protrusion into the vertebral canal and displacement of the spinal cord with an associated bone spur were identified. A microsurgical thoracic discectomy was performed. Immediately, the pain began resolving, and she was pain free and off her medications within several weeks. To our knowledge, this is the first description of a herniated thoracic disc presenting as the pain of chronic pancreatitis. The diagnosis of thoracic disc syndrome requires a high index of suspicion and should be considered in patients with chronic abdominal pain.

Abdominal Pain↗

PubMed1994

Click-evoked responses from the cochlear nucleus: a study in human.

Recordings from the vicinity of the cochlear nucleus in 9 patients undergoing microvascular decompression operations to relieve hemifacial spasm, trigeminal neuralgia, tinnitus, and disabling positional vertigo were conducted by placing a monopolar electrode in the lateral recess of the fourth ventricle (through the foramen of Luschka), the floor of which is the dorsolateral surface of the dorsal cochlear nucleus. The click-evoked potentials recorded by such an electrode display a slow negative wave with a peak latency of about 6-7 msec on which several sharp peaks are superimposed. None of the peaks in the recordings from the vicinity of the cochlear nucleus coincided with any vertex-positive peaks of the brain-stem auditory evoked potentials. In recordings from the lateral aspect of the floor of the fourth ventricle near the cochlear nucleus 1 patient showed 2 positive peaks, the earliest of which had a latency close to that of peak II and the second of which had a latency close to the negative peak between peaks III and IV of the brain-stem auditory evoked potentials. There is a distinct negative peak in the responses recorded from the midline of the floor of the fourth ventricle, the latency of which is only slightly shorter than that of peak V of the brain-stem auditory evoked potentials, supporting earlier findings that the sharp tip of peak V of the brain-stem auditory evoked potentials is generated by the termination of the lateral lemniscus in the inferior colliculus.

Acoustic Stimulation↗

PubMed1994

Preservation of hearing in operations on acoustic tumors: an alternative to recording brain stem auditory evoked potentials.

The monitoring of auditory function by recording brain stem auditory evoked potentials in patients undergoing removal of acoustic tumors is hampered by the small amplitude of the brain stem auditory evoked potentials. Because several thousands of responses must be added, it takes several minutes to obtain an interpretable record. Recordings done directly from the exposed eighth nerve have much higher amplitudes, and, therefore, interpretable responses can be obtained after only a few responses have been added. However, it is difficult to place the recording electrode in an optimal position and the electrode may interfere with the removal of the tumor. In this report, we show that evoked potentials from the cochlear nucleus, which can be recorded by placing an electrode in the lateral recess of the fourth ventricle, have a large amplitude, and that the electrode placed in this way does not interfere with the removal of the tumor. This way of monitoring, therefore, yields interpretable responses within 15 to 20 seconds, or less, and makes it possible to detect injuries to the entire intracranial portion of the eighth nerve, just as brain stem auditory evoked potentials do, but 20 to 50 times faster.

Acoustic Stimulation↗

PubMed1994

Microvascular decompression for trigeminal neuralgia caused by vertebrobasilar compression.

Thirty-one (2%) of 1404 consecutive patients with typical trigeminal neuralgia who underwent microvascular decompression between 1972 and 1993 were found to have vascular compression by the vertebral artery (VA) or the basilar artery (BA). Compared to the remaining 1373 patients, this subgroup was older (mean age 62 vs. 55 years, p < 0.001), was predominantly male (68% vs. 39%, p < 0.002), demonstrated left-sided predominance (65% vs. 39%, p < 0.002), was more likely to be hypertensive (65% vs. 18%, p < 0.001), and was more likely to have ipsilateral hemifacial spasm (16% vs. 0.6%, p < 0.001). The trigeminal nerve was compressed by the VA in 18 cases (the VA alone in three and the VA plus other vessels in 15), the BA in 12 cases (the BA alone in four and the BA plus other vessels in eight), and the vertebrobasilar junction in one case. Twenty-nine of the 31 patients underwent vascular decompression of the trigeminal nerve, one had a complete trigeminal root section, and one underwent partial root section with vascular decompression of the remaining nerve. All 31 patients were pain-free, off medication immediately after surgery, and this pain-free, medication-free status was maintained at 1 year after surgery in 96% of cases, at 3 years in 92%, and at 10 years in 86%, based on life-table analysis. Minor trigeminal hypesthesia/hypalgesia was present preoperatively in 52%. New or worsened minor hypesthesia/hypalgesia developed in 41% of patients, while transient diplopia as well as hearing loss developed in 23% and 13% in the overall series, respectively. No patient developed major trigeminal sensory loss or masseter weakness after vascular decompression alone. There was no operative mortality. Vascular decompression is an effective treatment for patients with trigeminal neuralgia who have vertebrobasilar compression of the trigeminal nerve. Patients should be warned that decompression of a tortuous vertebrobasilar system carries a higher risk of mild trigeminal dysfunction, diplopia, and hearing loss than standard microvascular decompression.

Age Factors↗

PubMed1993

Vascular decompression surgery for severe tinnitus: selection criteria and results.

Seventy-four patients were operated on within a period of 10 years to treat incapacitating tinnitus; 72 underwent microvascular decompression (MVD) of the intracranial portion of the auditory nerve, and 2 underwent section of the eighth nerve close to the brain stem. Of those who underwent MVD, 2 had no change in symptoms and later also underwent section of the eighth nerve near the brain stem. Two patients did not return for follow-up. Of the 72 remaining patients, 13 (18.1%) experienced total relief from tinnitus, 16 (22.2%) showed marked improvement, 8 (11.1%) showed slight improvement, 33 (45.8%) had no improvement, and 2 (2.8%) became worse. The patients who experienced total relief and those who showed marked improvement had experienced their tinnitus for an average of 2.9 years and 2.7 years, respectively; those who showed slight improvement and those who had no improvement had experienced their tinnitus for a longer time before the operation (mean, 5.2 and 7.9 years, respectively). Of the 72 patients who were operated on and followed, 32 were women. Of these, 54.8% experienced total relief from tinnitus or marked improvement, while only 29.3% of the men showed such relief or improvement. Selection of the patients for operation was mainly based on patient history and, to some extent, on auditory test results (brainstem auditory evoked potentials [BAEP], acoustic middle ear reflexes, and audiometric data).

Adolescent↗

PubMed1993

Abnormal response from the sternocleidomastoid muscle in patients with spasmodic torticollis: observations during microvascular decompression operations.

Electromyographic (EMG) recordings from patients undergoing microvascular decompression (MVD) operations to relieve spasmodic torticollis were studied. When EMG potentials were recorded from the sternocleidomastoid muscle in response to electrical stimulation of the spinal accessory nerve (SAN) at the neck, an abnormal (delayed) response was seen in 9 of 12 patients who had unilateral symptoms. In 5 patients with bilateral symptoms, no such delayed response was seen. We assume that this abnormal muscle response depends on an abnormal cross-transmission. Neural conduction time measurements, using electrical stimulation of the intracranial portion of the SAN, indicated that the location of this cross-transmission was more central than the vascular compression of the SAN. We hypothesize that this location might be in the motonucleus of the SAN. Similarities between these abnormal EMG findings in patients with spasmodic torticollis and those reported earlier in patients with hemifacial spasm (HFS) are presented.

Accessory Nerve↗

PubMed1993

Microvascular decompression of the eighth nerve in patients with disabling positional vertigo: selection criteria and operative results in 207 patients.

Two-hundred seven patients who were operated on consecutively between January 1983 and December 1990 to relieve disabling positional vertigo (DPV) using the microvascular decompression (MVD) procedure were studied. Selection of the patients for MVD operations was based on both case history and the results of otoneurological tests. Of the 177 patients with unilateral symptoms, 8 were excluded because of previous vestibular nerve section, and 6 did not return for follow-up; of the remaining 163 patients, 129 (79%) were free of symptoms or markedly improved following MVD, and none became worse. Thirty patients had symptoms and signs of bilateral DPV, and of these 1 was excluded because of previous vestibular nerve section and 3 because of multiple operations. Of the remaining 26 patients, 20 (77%) were free of symptoms or markedly improved following MVD. Eleven of these patients had more than 2 operations. The follow-up time was an average of 38 months, ranging from 3 months to 10 years. The cure rate (about 80%) of MVD for DPV is similar to that reported for MVD for trigeminal neuralgia and hemifacial spasm. The cure rate of MVD for DPV was not related to gender or to the duration of the symptoms. Following a total of 254 operations that these 207 patients underwent, 4 patients (1.6%) lost hearing and 4 (1.6%) suffered marked hearing loss. Three patients suffered temporary deficits of other cranial nerves. There were no other complications to these operations.

Adult↗

PubMed1992

Compound action potentials recorded from the exposed eighth nerve in patients with intractable tinnitus.

Compound action potentials (CAP) were recorded directly from the exposed intracranial portion of the eighth nerve in 19 patients undergoing microvascular decompression (MVD) of the eighth nerve for intractable tinnitus. The waveform of the CAPs recorded in patients with tinnitus varied from normal to highly abnormal, but only in 1 patient were there distinct abnormalities in the waveform of the CAP that could not be attributed to the patient's hearing loss. The mean values of the latencies of the N1 and N2 peaks in the CAPs recorded from the exposed eighth nerve in patients with tinnitus and high-frequency hearing loss were virtually indistinguishable from the latencies obtained in patients with similar hearing loss but no tinnitus. There was no statistically significant difference between the latency of peak III in the brainstem auditory evoked potentials (BAEPs) in these two groups of patients, but the latency of peak V was slightly shorter (statistically significant) in the patients with tinnitus than it was in the patients without tinnitus.

Action Potentials↗

PubMed1991

Effect of high-frequency hearing loss on compound action potentials recorded from the intracranial portion of the human eighth nerve.

Compound action potentials (CAP) were recorded from the exposed intracranial portion of the eighth nerve to stimulation with click sounds in patients with sensorineural high-frequency hearing loss who underwent microvascular decompression (MVD) operations to treat trigeminal neuralgia (TN). In patients with normal hearing the CAP recorded in that way is characterized by a negative peak, preceded by a small positivity and followed by a positivity and sometimes a second negative peak. In patients with high-frequency hearing loss the CAP also usually had an initial sharp negative peak in response to clicks of high intensity (105 to 110 dB Pe SPL), similar to findings in patients with normal hearing, but in patients with high-frequency hearing loss the initial negative peak was often followed by a slow negative deflection. The latency of the initial negative peak in the CAP in patients with high-frequency hearing loss was longer than the latency of this peak in patients with normal hearing, but the difference in latencies of this peak to condensation and rarefaction clicks was small. When the stimulus intensity was lowered the amplitude of the initial peak decreased, and the CAP became dominated by a broad negative peak with a latency of 6 to 8 ms. In 11 of 15 patients with severe high-frequency hearing loss, a series of quasi-periodic waves was superimposed on the CAP. The frequency of these waves varied between 500 and 1200 Hz, and the waves could be detected between 6 and 16 ms after presentation of the click stimulus. These waves were usually present in the response to stimuli in the intensity range from 75 to 110 dB Pe SPL. Only 4 of 17 patients with normal hearing had similar waves.

Acoustic Stimulation↗

PubMed1991

Auditory nerve compound action potentials and brain stem auditory evoked potentials in patients with various degrees of hearing loss.

Click-evoked compound action potentials recorded in normal-hearing patients through a monopolar electrode placed on the intracranial portion of the eighth nerve were compared with the responses recorded in patients with high-frequency hearing loss or with high- and low-frequency hearing losses. That multiple peaks appear in the compound action potential in patients with hearing loss implies that click sounds elicit successive and separated volleys of neural excitation in the ascending auditory pathway, whereas click sounds in patients with normal hearing mainly give rise to a single volley of neural activity. This difference in the pattern of auditory nerve activity might explain why there are often multiple peaks in the brain stem auditory evoked potentials in patients with hearing loss and that the peaks are often less well-defined than peaks in patients with normal hearing.

Audiometry, Evoked Response↗

PubMed1991

Compound action potentials recorded from the intracranial portion of the auditory nerve in man: effects of stimulus intensity and polarity.

Compound action potentials (CAP) were recorded from the intracranial portion of the eighth nerve in patients with normal hearing who were undergoing neurosurgical operations for cranial nerve disorders (trigeminal neuralgia and hemifacial spasm). Brain-stem auditory-evoked potentials were recorded intraoperatively to ensure that no noticeable changes occurred in conduction in the auditory nerve as a result of surgical dissections. The CAP recorded from the middle portion of the exposed intracranial portion of the eighth nerve in response to clicks of high intensity (100-110 dB peak equivalent SPL, or pe SPL) had a triphasic shape, as is commonly seen in monopolar recordings from long nerves. A second negative peak (N2) could be identified in some patients. There was little difference in the waveform of the CAP in response to condensation and rarefaction clicks, and in some patients the waveform of the CAP remained the same over a range of stimulus intensities (from 105 to 75 dB pe SPL), whereas in others the negative peak of the CAP became much broader in response to stimuli with intensities of less than 85 dB. In some patients the N2 peak became dominant as the stimulus intensity was decreased. At low stimulus intensities, the response consisted of a single, broad negativity. The latency-intensity curves for the N1 peak had different slopes in different patients. In those individuals in whom there was a noticeable difference between the latency of the N1 peak in response to clicks of opposite polarity, the latency-intensity curves of the responses to rarefaction clicks were steeper than those of the responses to condensation clicks, and the latency of the N1 peak to condensation clicks became shorter than that to rarefaction clicks at intensities below 85-90 dB pe SPL. The latency-intensity curves for the N2 peak were usually less steep than those of the N1 peak, but in some patients the curves for these two peaks had similar slopes. The amplitude of the N1 peaks showed a steep increase in click intensities at 95 and 105 dB, and a much less steep course for intensities below 95 dB. The amplitudes of the N2 peak reached a plateau in the range 95-105 dB, and decreased more rapidly than the N1 peak below 95 dB.

Acoustic Stimulation↗

PubMed1990

Late components in the compound action potentials (CAP) recorded from the intracranial portion of the human eighth nerve.

The compound action potential (CAP) that can be recorded from the exposed intracranial portion of the eighth nerve in man to stimulation with broadband clicks of about 100 dB Pe SPL normally has an initial (small) positivity followed by a sharp negative peak with a latency of about 3 to 3.5 ms. The negative peak is usually followed by another positive-negative deflection with a latency of about 4 ms. Usually, no stimulus-related potential can be discerned at latencies longer than 5 ms. However, in a few patients we found a series of waves that occurred between 4 and 12 ms after the stimulation. The polarity of these waves reversed precisely (180 degrees phase shift) when the polarity of the sound was reversed. Thus, these waves appeared clearly when the responses to clicks of opposite polarity were subtracted. These late waves were quasiperiodic with intervals between 1 and 2 ms. The waveform and duration differed between patients, but were remarkably constant in each patient. The timing of these late peaks was nearly independent of the stimulus intensity in the range studied (between 105 and 70 dB Pe SPL); in this respect the late waves differ fundamentally from the initial peaks, which showed a monotone decrease in latency with increasing stimulus intensity over this intensity range. Although the origin of these late waves is not known, the similarities between these waves and stimulated otoacoustic emissions indicate that the late waves may be the result of active cochlear processes similar to those that produce the cochlear echo.

Acoustic Stimulation↗

PubMed1990

Recordings from human dorsal column nuclei using stimulation of the lower limb.

Responses from the surface of the dorsal column nuclei and the dorsal surface of the spinal cord were recorded using monopolar electrodes after stimulation of the lower limbs (common peroneal nerve at the knee and posterior tibial nerve at the ankle) in patients undergoing neurosurgical operations for spasmodic torticollis. Those responses were smaller in amplitude than responses to stimulation of the upper limbs (median nerve at the wrist), and the waveforms differed. The negative deflection that is prominent in the response to stimulation of the upper limbs is more variable, broader, and relatively smaller in amplitude than the response to upper limb stimulation. Another difference between responses to upper and lower limb stimulation was that multiple peaks were superimposed on the initial response to stimulation of the lower limbs, but were not as consistently seen in the responses to upper limb stimulation. The negative peak in the response from the dorsal column nuclei to lower limb stimulation was of about the same latency as the P27 peak in the far-field response (somatosensory evoked potential) to stimulation of the peroneal nerve.

Action Potentials↗

PubMed1990

Saphenous vein graft bypass of the cavernous internal carotid artery.

Saphenous vein graft reconstruction was performed from the petrous to the supraclinoid internal carotid artery (ICA) to replace the cavernous ICA in six patients during direct intracavernous operations. Four of these patients had intracavernous neoplasms with invasion of the ICA and two had intracavernous ICA aneurysms that could not be clipped or occluded with intraluminal balloons. All but one patient had evidence of poor collateral flow reserve in a balloon occlusion test of the ICA. The superficial temporal artery was not present in four patients, was minuscule in one, and was damaged during the initial dissection in another, making it unsuitable for superficial temporal-to-middle cerebral artery branch anastomosis. Blood flow within the graft could not be established intraoperatively in one patient (who had excellent collateral circulation) due to the small size of the vein (3 mm). In all others, the grafts were patent on follow-up arteriography and transcranial Doppler studies. Three patients who had severe reduction of cerebral blood flow during test occlusion of the ICA exhibited temporary hemispheric neurological deficits postoperatively; the deficits were related to the duration of temporary ICA occlusion. All three recovered completely without evidence of infarction on computerized tomography (CT). One patient who clinically could not tolerate the balloon occlusion test of the ICA also had temporary neurological deficits with good recovery but showed evidence of border-zone infarction on CT scans. The present role of saphenous vein graft bypass of the cavernous ICA is discussed.

Adult↗