Case Reports in Medicine radiological workup that comprised cranial but no spinal MRI. The hint for spinal pathology came from insistent focal symptoms without true spreading over time. Only about 10% of ALS patients present solely with amyotrophy in limb muscles; widespread involvement usually follows. Weakness and atrophy at onset are more frequent in the upper limbs than in the lower limbs or bulbar muscles [7]. Furthermore, proximal muscles, such as the shoulders, are less commonly involved at the beginning [7]. ALS patients may suﬀer from neck pain, secondary to overstraining, when pain radiation is usually to the shoulders, rather than down the arms, which can be useful in diﬀerentiating ALS from myelopathy [1]. Somatosensory symptoms occur in about 10% of ALS cases but tend to be mild, short lived, and more apparent in the early stages [7]. In our case, the patient had experienced intermittent, cramp-like sensations of the chest wall as an early complaint. Retrospectively, and in the context of analysing potential misclassiﬁcations, this type of pain syndrome should have raised the suspicion of a spinal pathology. It has been estimated that up to 10% of patients initially diagnosed as ALS are ultimately rediagnosed as having a diﬀerent disease. Importantly, for about half of these patients potentially curative treatments exist [8]. This latter percentage was estimated in an investigation of 552 registered ALS patients reported by Davenport et al.: in this report, speciﬁc treatment options were identiﬁed for 23 patients, half of 46 for which an alternative diagnosis was made. The predominant reasons which led to a diagnostic revision were failure of symptom progression, development of atypical clinical features for MND, and investigation results [8]. More than 90% of patients with ALS mimic syndromes reported by Traynor et al. had presented with symptoms referable to the limbs and without signs of bulbar involvement, similar to our case [7]. Two of 32 patients had noncompressive myelopathy and one had cer- vical spondylitic myelopathy [7], thus cervicothoracic cysts probably represent rare causes of ALS mimic syndromes. In terms of prognosis, our case adds to reports on giant cervicothoracic cysts with excellent outcome after surgery [3, 9–12]. The delayed detection of a spinal pathology in our case alerts to strict adherence to the accepted Escorial scheme that deﬁnes the “lack of other neuroimaging evidence of other disease processes” as one of ﬁve essential criteria [2]. Another essential precondition for a diagnosis of ALS is the “progressive spread of symptoms or signs within a region or to other regions, as determined by history or examination” [2]. This criterion is pivotal since progression is typical for true motor neuron disease. In fact, our patient showed local progression in terms of increasing muscle atrophy, weakness of the upper limbs, and worsening of gait ataxia, compatible with an increasing space-occupying eﬀect of the cyst. However, no unequivocal spread of lower motor neuron signs to the lower limbs or the brainstem was noted. In conclusion, cervivothoracic arachnoid cysts could be added to the group of treatable ALS mimic syndromes. 3 Careful longitudinal clinical assessment, complete applica- tion of diagnostic measures including spinal imaging, and strict adherence to recommended diagnostic criteria of ALS as a minimum standard are essential. Speciﬁc attention to the possibility of ALS mimic syndromes is needed when there is clinical evidence of neuronal involvement outside the motor system, an unusual distribution of muscle atrophy with lack of spreading to other regions or persisting sensory or pain symptoms. Such clinical features should alert the physi- cian to question the diagnosis and take further diagnostic measures. Acknowledgment P. G. Sa¨mann and H. Himmerich have contributed equally. References [1] J. A. Rocha, C. Reis, F. Simo˜es, J. Fonseca, and J. Mendes Ribeiro, “Diagnostic investigation and multidisciplinary man- agement in motor neuron disease,” Journal of Neurology, vol. 252, no. 12, pp. 1435–1447, 2005. [2] B. R. Brooks, R. G. Miller, M. Swash, and T. L. Munsat, “El Escorial revisited: revised criteria for the diagnosis of amyotrophic lateral sclerosis,” Amyotrophic Lateral Sclerosis and Other Motor Neuron Disorders, vol. 1, no. 5, pp. 293–299, 2000. [3] K. Korosue, H. Shibasaki, Y. Kuroiwa, et al., “Cyst of the conus medullaris manifesting amyotrophic lateral sclerosis syndrome,” Folia Psychiatrica et Neurologica Japonica, vol. 35, no. 4, pp. 507–510, 1981. [4] R. H. Wilkins, “Intraspinal cysts,” in Neurosurgery, R. H. Wilkins and S. S. Rengachary, Eds., pp. 3509–3519, McGraw- Hill, New York, NY, USA, 2007. [5] R. K. Osenbach, J. C. Godersky, V. C. Traynelis, and R. D. Schelper, “Intradural extramedullary cysts of the spinal canal: clinical presentation, radiographic diagnosis, and surgical management,” Journal of Neurosurgery, vol. 30, no. 1, pp. 35– 42, 1992. [6] K. Osuka, M. Takayasu, T. Tanazawa, K. Ichihara, and Y. Itoh, “Multiple communicating intradural arachnoid cysts: usefulness of myelography and myelo-computed tomography using both lumbar and cervical punctures. Case report,” Neurosurgical Review, vol. 20, no. 2, pp. 94–98, 1997. [7] B. J. Traynor, M. B. Codd, B. Corr, C. Forde, E. Frost, and O. Hardiman, “Amyotrophic lateral sclerosis mimic syndromes: a population-based study,” Archives of Neurology, vol. 57, no. 1, pp. 109–113, 2000. [8] R. J. Davenport, R. J. Swingler, A. M. Chancellor, and C. P. Warlow, “Avoiding false positive diagnoses of motor neuron disease: lessons from the Scottish motor neuron disease register,” Journal of Neurology, Neurosurgery, and Psychiatry, vol. 60, no. 2, pp. 147–151, 1996. [9] H.-J. Chen and L. Chen, “Traumatic interdural arachnoid cyst in the upper cervical spine: case report,” Journal of Neurosurgery, vol. 85, no. 2, pp. 351–353, 1996. [10] M. K. Hamamcioglu, C. Kilincer, T. Hicdonmez, O. Simsek, B. Birgili, and S. Cobanoglu, “Giant cervicothoracic extradural arachnoid cyst: case report,” European Spine Journal, vol. 15, supplement 5, pp. S595–S598, 2006.