Neurological symptoms in a patient with isolated adrenocorticotropin deficiency: case report and literature review

Abstract

Background: Isolated adrenocorticotropic hormone (ACTH) deficiency is a pituitary disorder characterized by reduction only in the secretion of ACTH. Although the underlying mechanism remains to be elucidated, numbers of cases with this entity have been increasing. We experienced a case presenting with gait disturbance necessitating differential diagnosis from idiopathic normal pressure hydrocephalus (iNPH).

Case presentation: A 69-year-old female with a complaint of difficulty walking and suspected to have iNPH at a prior hospital was referred to our department. For the prior three years, she had suffered from a progressive gait disturbance. Magnetic resonance imaging (MRI) revealed global ventricular dilatation. The typical features of the gait in iNPH cases were all identifiable. Neuropsychological dementia scale tests showed deterioration. However, the major feature of a disproportionately enlarged subarachnoid-space on MRI was not obvious. The patient developed progressively worsening fatigue during hospitalization. Her symptoms resembled those of hypothalamic-pituitary tumor patients. Serum ACTH and cortisol levels were low. While corticotrophin releasing hormone stress tests showed no response, other stress tests using thyrotropin releasing hormone, luteinizing hormone releasing hormone, and growth hormone releasing hormone yielded normal responses, indicating a diagnosis of isolated ACTH deficiency. We initiated corticosteroid therapy, and her gait disturbance improved promptly.

Conclusion: Isolated ACTH deficiency may have major significance to the differential diagnosis of iNPH. Early consideration of this entity is anticipated to facilitate making an early diagnosis.

Fig. 1

Upper: T2-weighted axial MRI revealed enlarged ventricles. Lower: In T2-weighted coronal MRI also showed enlarged ventricles, however, the major feature of disproportionately enlarged subarachnoid-space was not obvious

Fig. 2

Single-photon emission computed tomography revealed areas of relatively decreased blood perfusion around the Sylvian fissure, while increased blood perfusion in the external layer around the convexity side

Fig. 3

MRI showed normal pituitary gland measuring 12 mm in maximum diameter with no deviation of stalk, and there is no tumor or inflammatory lesion around the hypothalamic-pituitary area. (Upper left: T1 coronal MRI, Upper right: T1 gadolinium coronal MRI, Upper right: T1 gadolinium sagittal MRI, lower left: T1 gadolinium sagittal MRI)

Fig. 4

Pituitary stimulation test using corticotropin-releasing hormone, thyrotropin-releasing hormone, luteinizing hormone-releasing hormone and growth hormone releasing hormone showed no response in plasma cortisol level and ACTH level, while other hormones showed adequate response