N the 1990s, bilateral STNS provided dramatic relief for many patients suffering from advanced PD, and it was soon established as the neurosurgical intervention of choice in such cases. 10 In a recent study, 6 motor scores improved by a median of 49% at 3 months, and the per- centage of time during the day that patients had good mobility without involuntary movements increased from 27% to 74%. Yet, undergoing STNS carries a serious risk of intracranial hemorrhage (up to 5% in large series), which can be disabling or fatal. 6,10 In addition, at least 30% of the patients are not suitable for surgery: these are pa- tients who score less than 30 to 40 in the off condition on Part III of the UPDRS or have an improvement of less than 40 to 50% when undergoing the levodopa challenge test. 9 In addition, patients in whom cortical atrophy or focal lesions are present and those showing severe psy- chiatric disturbances and cognitive decline in the off phase are generally excluded. 11 A patient age of 70 years is an upper limit for surgery at several centers. In the early decades of the 20th century, Bucy relieved PD symptoms by surgical ablation of the PMC, 14 although this was done at the expense of severe motor deficits. In 1979, Woolsey and coworkers 17 relieved both tremor and rigidity in two patients with PD during acute intraopera- tive stimulation of the PMC. In 1991, extradural MCS was reported by Tsubokawa, et al.; 16 MCS is a minimally inva- sive technique for pain control with no reported mortality, minimal morbidity, and no serious adverse effects. 2 Starting from these published observations, we per- formed chronic unilateral stimulation of the PMC in a patient with PD who did not meet the inclusion criteria for STNS, which resulted in dramatic improvement. 3 We re- port the long-term benefit in that first patient as well as in an additional patient. Case Reports Case 1 History. This 75-year-old woman, in whom the gradual development of typical PD was diagnosed in 1976, pre- sented in 1998. At presentation she scored IV–V on the Hoehn and Yahr Scale and showed moderate-to-severe PD-associated dementia. Examination and Initial Treatment. A CT scan revealed marked cerebral atrophy. She scored 44 on Part III (motor) of the UPDRS while receiving levodopa. 3 Left unilateral extradural MCS was performed and improvement in her symptoms was dramatic (Fig. 1). Choreiform dyskinesias and painful focal dystonias of the right foot seen preoperatively were absent and, she could walk independently. The best stimulation parame- ters were 3 V, 180 msec, 25 Hz, and a 3+/0 setting; stim- ulation did not take place during sleep. Five months after stimulator implantation, a direct injury resulted in wound dehiscence, local infection, and system failure. Clinical worsening started approximately 4 days later with a slow worsening of gait and postural stability over a 2-week period. The infection was successfully treated. In April 1999, a new system (ITREL III; Medtronic, Minneapolis, MN) was implanted when the prestimulation level was almost present. Benefit was as for the first implantation and levodopa was further reduced to -80%. In particular, she could walk independently and lift a glass without spilling the contents. By April 2002, the results of her neu- rological examination revealed absence of rigidity, trochlea, and tremor to all four limbs. Independent ambu- lation was possible most of the time. Her posture was slightly camptocormic. Stimulation parameters were 3.5 Abbreviations used in this paper: CT = computerized tomogra- phy; ECD = ethyl cysteinate dimer; GABA = gamma aminobutyric acid; IBZM = iodine-123 iodobenzamide; MCS = motor cortex stimulation; MR = magnetic resonance; PD = Parkinson disease; PMC = primary motor cortex; SPECT = single-photon emission CT; STNS = subthalamic nucleus stimulation; UPDRS = Unified PD Rating Scale. J Neurosurg 97:1208–1211, 2002 1208 Extradural motor cortex stimulation for advanced Parkinson disease Report of two cases SERGIO CANAVERO, M.D., RICCARDO P AOLOTTI, M.D., VINCENZO BONICALZI, M.D., GIANCARLO CASTELLANO, M.D., STEFANIA GRECO-CRASTO, M.D., LAURA RIZZO, M.D., OTTAVIO DAVINI, M.D., FRANCESCO ZENGA, M.D., AND P AOLA RAGAZZI, M.D. Neuromodulation Unit, Department of Neurosciences; and Department of Radiology and Nuclear Medicine; Molinette Hospital, Turin, Italy  Motor cortex stimulation is a minimally invasive surgical procedure used for pain control. The authors report their results treating two patients with typical Parkinson disease. Unilateral motor cortex stimulation proved to be beneficial bilaterally. Motor cortex stimulation may represent a cost-effective alternative to deep brain stimulation. KEY WORDS • Parkinson disease • motor cortex stimulation I J. Neurosurg. / Volume 97 / November, 2002