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Object This prospective study on intraoperative muscle motor evoked potentials (MMEPs) from lower-limb muscles in patients undergoing surgery for spinal cord tumors was performed to: 1) determine preoperative clinical features that could predict successful recording of lower-limb MMEPs; 2) determine the muscle in the lower limb from which MMEPs could be most consistently obtained; 3) assess the need to monitor more than 1 muscle per limb; and 4) determine the effect of a successful baseline MMEP recording on early postoperative motor outcome. Methods Of 115 consecutive patients undergoing surgery for spinal cord tumors, 110 were included in this study (44 intramedullary and 66 intradural extramedullary tumors). Muscle MEPs were generated using transcranial electrical stimulation under controlled anesthesia and were recorded from the tibialis anterior, quadriceps, soleus, and external anal sphincter muscles bilaterally. The effect of age (≤ 20 or > 20 years old), location of the tumor (intramedullary or extramedullary), segmental location of the tumor (cervical, thoracic, or lumbar), duration of symptoms (≤ 12 or > 12 months), preoperative functional grade (Nurick Grades 0–3 or 4–5), and muscle power (Medical Research Council Grades 0/5–3/5 or 4/5–5/5) on the success rate of obtaining MMEPs was studied using multiple regression analysis. The effect of the ability to monitor MMEPs on motor outcome at discharge from the hospital was also analyzed. Results The overall success rate for obtaining baseline lower-limb MMEPs was 68.2% (75 of 110 patients). Eighty-nine percent of patients with Nurick Grades 0–3 had successful MMEP recordings. Muscle MEPs could not be obtained in any patient in whom muscle power was 2/5 or less, but were obtained from 91.4% of patients with muscle power of 4/5 or more. Analysis showed that only preoperative Nurick grade (p ≤ 0.0001) and muscle power (p < 0.0001) were significant predictors of the likelihood of obtaining MMEPs. Responses were most consistently obtained from the tibialis anterior muscle (68%), but in the other 32% MMEPs could not be recorded from the tibialis anterior but could be recorded from another muscle. The ability to monitor MMEPs was associated with better motor outcome at discharge from the hospital (p = 0.052). Conclusions The likelihood of obtaining lower-limb MMEPs is significantly greater in patients with better functional grades and higher motor power. Muscle MEPs are most consistently obtained from the tibialis anterior muscle but other muscles should also be monitored to optimize the chances of obtaining MMEP responses from the lower limbs.

The aim of this study was to analyse the complete profile and outcome of patients with idiopathic giant cell granulomatous hypophysitis. Six consecutive cases of idiopathic giant cell granulomatous hypophysitis were studied from 1993 to 2002. Headache and visual disturbances were the most frequent presenting symptoms. All patients had hypogonadism, four had hypoadrenalism and three were hypothyroid at presentation. None of them had diabetes insipidus preoperatively. A sellar mass with suprasellar extension on MRI with loss of the posterior pituitary 'bright spot' was a consistent observation in all patients. All patients underwent surgical excision of the mass lesion with histopathological confirmation of giant cell granulomatous hypophysitis. Other systemic granulomatous diseases were excluded by appropriate investigations. Postoperatively, all patients became hypothyroid and hypogonad, five patients had adrenal insufficiency, while two developed permanent diabetes insipidus. The clinical presentation of giant cell granulomatous hypophysitis is that of an expanding sellar mass lesion with a varying degree of endocrine dysfunction. Preoperative diagnosis of 'hypophysitis' is usually difficult; however, stalk thickening and loss of posterior pituitary 'bright spot' on MR imaging are clues to the diagnosis.

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