A 46-year-old female functionary presented to the department of neurology in our hospital with progressive left arm pain and weakness for 3 months. The excruciating radiating pain in her left shoulder and arm occurred 3-4 times every hour and lasted for 10 min per episode. Sustained weakness of the left arm made her unable to comb her hair. She denied fever before or during the disease, but she lost 2 kg of weight because of poor appetite due to the pain. The patient had a history of meningioma resection 3 years ago. However, she denied any intracranial symptoms, and the surgical incision healed well. Recent reexamination of brain MRI was also normal. There was no history of trauma or dental procedures. The patient was allergic to amoxicillin.
Upon physical examination, the patient was afebrile with normal vital signs. No lymphadenopathy was palpated. Cardiovascular, respiratory and abdominal examinations were unremarkable. Upon neurologic examination, the cranial nerve examination was normal. Weakness and atrophy of the following muscles were noted: deltoid (Medical Research Council [MRC] grade 4 -/5), triceps (MRC 3/5), biceps (MRC 3/5), and distal muscles (MRC 4/5) of the left upper limb. The muscle tone of the left upper limb was slightly decreased. All tendon reflexes were reduced in the left upper limb. Sensory examination revealed hypoalgesia on the lateral side of the left upper limb, left thumb, and index finger. Pathological reflexes and meningeal irritation were negative.
The patient had previously undergone cervical spine magnetic resonance imaging (MRI) elsewhere. At the C5-C6 level, the lesion partially surrounded the left vertebral artery and extended through the left intervertebral foramen into the spinal canal (Figures 1A,B). On coronal MRI, the lesion spread from C4 to C7 in the spinal canal, especially demonstrating mass effect at the C5-C6 level (Figure 1C).
The electromyogram only revealed spontaneous potential in the left biceps brachii. Motor conduction studies of the bilateral median and ulnar nerves showed normal findings, as did the somatosensory evoked potential of the left upper limb.
Laboratory tests showed normal hemoglobin levels, total leucocyte count, platelet count, and erythrocyte sedimentation rate. T-SPOT.TB was positive, but a further Xpert MTB/RIF test of the sputum was negative. The following results were all normal: serologic tests for syphilis, Lyme disease, and HIV; serum autoimmune screening; and angiotensin-converting enzyme level measurements. A whole-body CT scan did not provide any evidence of underlying malignancy.
Upon lumbar puncture, the opening pressure was normal, and the cerebrospinal fluid (CSF) was clear and colorless. The CSF white blood cell count was elevated (505/mm3); lymphocytes (50%) and neutrophils (40%) were predominant. The CSF protein level was 70 mg/dL, and the CSF glucose level was 41.4 mg/dL. The CSF bacterial smear, bacterial culture, acid-fast staining, and fungal smear results were negative. No abnormalities were found in the CSF anti-GM1 antibody test. CSF cytology was negative for malignancy.
The patient's clinical manifestations indicated C5-C7 radiculopathy. The MRI findings confirmed the location of C4-C7 myeloradiculopathy. Combining the CSF profile of leukocytic pleocytosis, high protein level, and hypoglycorrhachia, inflammatory lesions were considered most likely. The patient was empirically treated with 2 g of intravenous ceftriaxone daily and with pulse intravenous methylprednisolone.
To establish the final diagnosis, an intraspinal biopsy was performed. The dural sac was opened from C5 to C6. During the biopsy, we observed an intrathecal gray-white mass on the left ventral side of the C5-C6 spinal cord surrounding the left C5-C6 nerve roots. The mass had a brittle texture and rich blood supply, and the base of the mass was on the dura mater (Figure 2A). The mass was partially resected, and we did not further explore the intervertebral foramen and epidural lesions to avoid bleeding and the spread of potential infection. Histopathological examination of the resected mass showed a colony of Gram-positive, acid-fast staining negative, periodic acid-Schiff staining positive and Grocott's methenamine silver staining positive filamentous branching bacteria, with hematoxylin and eosin (HE) staining revealing the Splendore-Hoeppli phenomenon (Figures 2B-F). In addition, histopathological examination also indicated a chronic inflammatory process involving epidural structures. Therefore, the patient was diagnosed with intraspinal actinomycosis based on the pathological evidence. However, no definite pathogenic microorganism was identified with tissue culture.
The intravenous dosage of ceftriaxone was then increased to 2 g twice daily, and prednisone acetate sequential therapy was administered. After a 3-month treatment regimen, the patient showed favorable neurological progression. Her left arm pain disappeared, and the strength of the proximal muscles increased to MRC 4+/5 and that of the distal muscles to MRC 5/5. The CSF white blood cell count decreased to 22/mm3.