[Methohexital for treatment of intracranial hypertension]. / Methohexital zur Therapie des erhöhten intrakraniellen Drucks.

BACKGROUND: Barbiturate coma therapy is a useful method to control increased intracranial pressure (ICP) in patients with severe brain damage if standard measures have failed to lower ICP. Pentobarbital (not available in Germany) and thiopental (in Germany only approved for induction of anesthesia) have frequently been used in patients with intracranial hypertension and the effects and side-effects are well-described. However, little is known about the effect of methohexital (the only barbiturate in Germany approved for maintaining anesthesia) in lowering increased ICP. Therefore, the effect of methohexital on ICP was studied in patients where standard measures had failed to control intracranial hypertension. METHOD: A retrospective observational study was carried out with the inclusion criteria of patient age ≥18 years and methohexital therapy for 12 h or more with ICP monitoring in place. Methohexital was administered following a standardized algorithm to patients for whom standard measures, such as deep anesthesia, normoventilation, cerebral perfusion pressure (CPP) >65 mmHg, osmotherapy, neurosurgical evacuation of mass lesions, had failed to lower ICP. Methohexital was used if the ICP had risen above 20-25 mmHg for more the 20-30 min and otherwise manageable causes for the ICP increase had been ruled out. Methohexital was given continuously in addition to standard analgesia and sedation in doses of 2-4-6 mg/kg body weight (BW), depending on the ICP lowering effect. The records of the patient data management system from the years 2008/2009 were used to compare the ICP and CPP before and during methohexital administration. For statistical analyses Student's t-test was applied for measured values and the χ(2)-test was applied for percentage values whereby p<0.05 was defined as being statistically significant. RESULTS: During the study period 36 patients required methohexital therapy and 30 fulfilled the inclusion criteria. In 26 out of 30 patients the data were complete and these 26 patients were included in the data analyses. Of the patients 6 (23%) died due to elevated intracranial hypertension and 20 patients (77%) survived. In all patients methohexital lowered the ICP from 25.2 mmHg (standard deviation, SD ±4.3 mmHg) to 19.8 mmHg (SD ±12.5 mmHg) within the first 24 h, this result closely failed to reach a level of significance. In the 20 survivors methohexital lowered the ICP from 25.88 mmHg (SD ±4.8 mmHg) to 14.25 mmHg (SD ±6.9 mmHg) within the first 24 h, which is statistically highly significant. In non-survivors the ICP had risen from 24 mmHg (SD ±2.6 mmHg) to 32 mmHg (SD ±16.3 mmHg) within the first 24 h despite all efforts. Due to the CPP driven volume and vasopressor therapy no significant changes in the CPP during methohexital administration were observed. No significant changes in brain temperature (as possible cause for the decrease of the ICP) were observed. Non-survivors received significantly more methohexital due to increased ICP and required significantly more vasopressor therapy to maintain a sufficient CPP. CONCLUSIONS: Methohexital showed a clear trend for decreasing ICP in patients with intracranial hypertension refractory to standard therapeutic measures. In survivors the effect was highly significant. Patients not responding to methohexital therapy seemed to have an unfavorable outcome.

Temporary cardiac asystolia induced by intraoperative irritation of the eighth right sided anterior cervical nerve root.

BACKGROUND: The 60 year old women with no prior history of arrhythmia or other cardiac symptoms was operated on for a cervical disc herniation at the level C7/D1. The C8 nerve root was visualized via a posterior approach. FINDINGS: Removal of the sequestrum and irritation of the anterior root with surgical instruments triggered cardiac arrest. INTERPRETATION: We offer the opinion that irritation of the anterior root led to diminished activity of the supraspinal sympathetic control system and consecutive hyper-activation of the parasympathetic system.

[Neurosurgical therapy of Parkinson disease. Deep brain stimulation]. / Neurochirurgische Therapie der Parkinson-Krankheit. Deep-Brain-Stimulation.

The introduction of continuous high frequency stimulation (deep brain stimulation) into functional neurosurgery has opened up new avenues in the treatment of Parkinson's disease. This new technique expands the therapeutic possibilities available to those patients in whom, over the years, the effectiveness of drug treatment has deteriorated, or severe side effects developed. In the individual case, the decision as to whether to operate is taken on the basis of interdisciplinary cooperation between the care-providing neurologist and the neurosurgeon specialized in this particular field.

Can continuous intraoperative facial electromyography predict facial nerve function following cerebellopontine angle surgery?

Intraoperative cranial nerve monitoring has significantly improved the preservation of facial nerve function following surgery in the cerebellopontine angle (CPA). Facial electromyography (EMG) was performed in 60 patients during CPA surgery. Pairs of needle electrodes were placed subdermally in the orbicularis oris and orbicularis oculi muscles. The duration of facial EMG activity was noted. Facial EMG potentials occurring in response to mechanical or metabolic irritation of the corresponding nerve were made audible by a loudspeaker. Immediate (4-7 days after tumor excision) and late (6 months after surgery) facial nerve function was assessed on a modified House-Brackmann scale. Late facial nerve function was good (House-Brackmann 1-2) in 29 of 60 patients, fair (House-Brackmann 3-4) in 14, and poor (House-Brackmann 5-6) in 17. Postmanipulation facial EMG activity exceeding 5 minutes in 15 patients was associated with poor late function in five, fair function in six, and good function in four cases. Postmanipulation facial EMG activity of 2-5 minutes in 30 patients was associated with good late facial nerve function in 20, fair in eight, and poor in two. The loss of facial EMG activity observed in 10 patients was always followed by poor function. Facial nerve function was preserved postoperatively in all five patients in whom facial EMG activity lasted less than 2 minutes. Facial EMG is a sensitive method for identifying the facial nerve during surgery in the CPA. EMG bursts are a very reliable indicator of intraoperative facial nerve manipulation, but the duration of these bursts do not necessarily correlate with short- or long-term facial nerve function despite the fact that burst duration reflects the severity of mechanical aggression to the facial nerve.

Intra-operative mapping of the motor cortex during surgery in and around the motor cortex.

The intra-operative use of neurophysiological techniques allows reliable identification of the sensorimotor region, and constitutes a prerequisite for its anatomical and functional preservation. The present prospective study combines monopolar cortical stimulation (MCS) with the recording of phase reversal of somatosensory evoked potentials (SEP-PR) in a protocol for the intra-operative mapping of the motor cortex. Functional mapping of the motor cortex by SEP-PR and MCS was performed in 70 patients during surgery in and around the motor cortex. The central sulcus was identified by SEP-PR. Cortical motor mapping was then performed by monopolar anodal (400 Hz) stimulation. Motor responses were recorded by needle electrodes placed in the muscles of the contralateral extremities. Surgery was performed under general anaesthesia without muscle relaxants. Intra-operative localization of the central sulcus by SEP-PR was possible in 68 patients (97.14%). Motor evoked potentials (MEP) were elicited following MCS in 67 cases (95.7%). In 3 cases no MEP was recorded, not even after maximal stimulation intensity, the central sulcus being localized by SEP-PR only. On the other hand, MCS allowed localizing the motor cortex in the 2 cases with no recordable SEP-PR. Thus, combining SEP-PR and MCS allowed intra-operative localization of the sensorimotor cortex in 100% of the cases.

Demonstration of cerebral plasticity by intra-operative neurophysiological monitoring: report of an uncommon case.

It has been postulated long ago that "eloquent" areas shift their location in patients with arteriovenous malformations (AVM). Obviously the "motor region" in not located in the precentral gyrus in a patient with an AVM in the "motor region". We report on the case of a 15-year old boy with an AVM in the left sensorimotor cortex, in whom intra-operative mapping showed an inexcitability of the precentral gyrus, while stimulation of the cortex anterior to the primary motor cortex elicited motor responses. This indicates that motor function was translocated from the primary to the supplementary motor cortex. Surgery was performed under general anaesthesia. Neurophysiological monitoring was performed throughout surgery. The central sulcus was identified by phase reversal of the somatosensory evoked potentials. The motor cortex was mapped by direct high-frequency (500 Hz) monopolar anodal stimulation. In the patient herein reported, stimulation of the "anatomically" defined primary motor cortex induced no motor response, as expected. Motor response was elicited only by stimulation of the cortex anterior to the precentral gyrus. There was no postoperative deterioration of motor function. These observations indicate that the precentral gyrus was functionally "useless". The motor region was relocated into more rostral areas in the supplementary motor cortex. This translocation of function in the presence of an AVM indicates cerebral plasticity.

Comparison between monopolar and bipolar electrical stimulation of the motor cortex.

Intra-operative neurophysiological techniques allow reliable identification of the sensorimotor region and make their anatomical and functional preservation feasible. Monopolar cortical stimulation has recently been described as a new mapping technique. In the present study this method was compared to the "traditional" technique of bipolar stimulation. Functional mapping of the motor cortex was performed in 35 patients during surgery in the central region. The central sulcus (CS) was identified by somatosensory evoked potential (SEP) phase reversal. Cortical motor mapping was first performed by monopolar anodal stimulation with a train of 500 Hz (7-10 pulses) followed by bipolar stimulation (pulses at 60 Hz with max. 4 sec train duration). Surgery was performed under general anaesthesia without muscle relaxants. Of 280 motor responses elicited by bipolar cortical stimulation, 54.23% [152] were located in the primary motor cortex (PMC), 37.85% 106[ outside the motor strip in the secondary motor cortex (SMC), and 8% 22[ posterior to the CS. Of 175 motor responses elicited by monopolar cortical stimulation. 68.57% 120[ were located in the SMC, 23.42% 41[ in the SMC and 8% 14[ posterior to the CS. Contrary to the general clinical view, there is considerable overlapping of primary motor units over a cortical area much broader than the "classical" narrow motor strip along the CS. Bipolar cortical stimulation is more sensitive than monopolar for mapping motor function in the premotor frontal cortex. Both methods are equally sensitive for mapping the primary motor cortex.

[Bilateral carpal tunnel syndrome--surgical therapy--prognostic factors and results]. / Das beidseitige Karpaltunnelsyndrome--Operative Therapie--prognostische Faktoren und Ergebnisse.

Patients submitted to bilateral section of the transverse carpal ligament suffer from predisposing diseases, hormonal alterations or have wrists exposed to increased occupational strain more frequently than patients with unilateral carpal tunnel syndrome. In addition, in this group of patients the results of neurophysiological tests are more markedly pathologic. The good initial operative results are frequently followed by a relapse of symptoms. There is no appreciable difference between the operative results for the right versus for the left hand nor between the hand operated on in the first versus in the second place. A long-term improvement of opposite side symptoms following the first operation only occurs in exceptional cases.

The recurrent carpal tunnel syndrome.

Sixteen out of 720 patients with carpal tunnel syndrome who had undergone surgery since 1979 were reoperated for a "recurrence" (2.2%). Twelve of these patients had been originally operated on in our department. Thus, our own recurrence rate is 1.7%. Three patients deteriorated following surgery, 6 had an unsatisfactory improvement, and in 7 the symptoms recurred after initial improvement. Eight of the reoperated patients had a predisposing disease (terminal renal insufficiency, insulin-dependent diabetes mellitus, acromegaly). In 10 of the 16 cases the initial operation had been carried out by surgeons in the first three years of training. Reoperation revealed incomplete splitting of the transverse carpal ligament in 10 cases, compression of the median nerve by the scar in 4, injury of the muscular branch in 1, and an anatomical variant as cause of incomplete decompression in 1 patient. "Recurrences" after carpal tunnel surgery are predominantly due to inadequacies of the first procedure. A remarkable number of patients (50%) has predisposing diseases. Interfascicular or epineural neurolysis and complete exposure and neurolysis of the median nerve and its branches is necessary only in cases of recurrence. Their omission at the first surgery does not result in an increased recurrence rate. Our observations indicate that the number of operations for recurrent carpal tunnel syndrome can probably be reduced when the first operation is performed with care and experience. Patients with carpal tunnel syndrome secondary to a systemic disease are particularly at risk.

[Surgical treatment of iatrogenic lesions of the accessory nerve following lymph node excision]. / Die operative Behandlung iatrogener Läsionen des N. accessorius nach Lymphknotenexstirpation.

Excision of lymph nodes on the lateral margin of the sterno-cleido-mastoid muscle may result in damage to the accessory nerve. Most commonly the branch to the trapezius is involved. The treatment in five cases of iatrogenic lesions is described. Contrary to the widespread assumption that these lesions are irreversible, there was significant improvement in all cases.

[Acute progressive paralysis caused by intraneural ganglion--a neurosurgical emergency]. / Akute progrediente Parese bei intraneuralem Ganglion--Ein neurochirurgischer Notfall.

Intraneural ganglia, particularly of the peroneal and ulnar nerves may produce rapidly progressive paresis after minor trauma, for instance, following a sport injury. The chance of recovery of nerve function depends on the timing of surgical treatment. A patient with a ganglion of the peroneal nerve is reported in order to stress the relevance of intraneural ganglia, the danger of missing the lesion and the importance of early treatment. It is stressed that in the presence of rapidly progressing paralysis and the clinical suspicion of an intraneural ganglion, early decompression offers the best prognosis for recovery.