Cervical Myelopathy Due to Ochronosis: An Intraoperative Suspicion

Abstract

BACKGROUND Alkaptonuria (AKU) is a rare metabolic disease caused by a deficiency in homogentisic acid oxidase, which leads to the accumulation of homogentisic acid dark pigments in tissues such as bones, ligaments, and tendons. Long-term duration of this condition, termed ochronosis, can result in degenerative arthropathy involving the spine and large joints. CASE REPORT This report describes a 55-year-old Jordanian woman presenting with chronic neck and lower back pain. History, physical examination, and radiological imaging indicated cervical myelopathy and lumbar spine degeneration. Two-level anterior cervical discectomy and fusion was performed successfully. Intra-operatively, the cervical discs were observed to be black, suggesting a diagnosis of alkaptonuria, which was later confirmed by genetic testing. A detailed history and physical examination revealed the absence of classical features of AKU. CONCLUSIONS Intraoperative detection of black disc material suggests the need for further tests to diagnose AKU, especially in indolent patients who did not have classical clinical features. Surgical management may improve outcomes in patients with cervical myelopathy due to ochronosis.

Figure 1.

AP and lateral radiographic views of the cervical spine of our patient at her initial visit (A) and 2 years later (B).

Figure 2.

AP and lateral views of lumbar spine radiographs.

Figure 3.

T2 MRI results in our patient. (A) Mid-sagittal T2 MRI of the cervical spine. (B) Sagittal and axial T2 MRI of the C3/4 level, showing large central disc protrusion compressing the thecal sac and spinal cord. (C) Sagittal and axial T2 MRI of the C4/5 level showing a large broad-based disc osteophyte complex compressing the thecal sac and narrowing both nerve root exit foramina.

Figure 4.

Intraoperative photograph showing the black colored disc.

Figure 5.

Postoperative AP and lateral radiographic views of the cervical spine.

Figure 6.

Urine sample showing the same color initially (A) and after 6 hours (B).

Figure 7.

Absence of dark pigmentation of the sclerae of both eyes.

Figure 8.

Absence of clear dark pigmentation of the pinnae of both ears.

Figure 9.

Absence of dark pigmentation of the oral cavity.