[ SHOWGSD-L ] Re: Nerve sheath tumors- anyone had this?
- From: MORGAN LEWIS <shadowland22000@xxxxxxxxx>
- To: "managsd@xxxxxxxxx" <managsd@xxxxxxxxx>, "Showgsd-l@xxxxxxxxxxxxx" <Showgsd-l@xxxxxxxxxxxxx>
- Date: Sat, 30 Mar 2013 14:58:35 -0700 (PDT)
Nerve Sheath Tumors
Description- A nerve sheath tumor is a type of tumor arising from the nervous
system (nervous system neoplasm) which is primarily made up of the myelin (it
forms a layer around the axon of a neuron) surrounding nerves. On the other
hand, peripheral neural sheath tumors are those originating from the peripheral
nervous system (it extends outside the central nervous system consisting of the
brain and spinal cord).
Peripheral neural sheath lesions can be divided into both benign and malignant.
The non-malignant ones can be further divided into schwannoma, neurofibromas
and hemangiopericytoma. The names may be different but they presumably
originate in the schwann cells surrounding the nerve axon. The malignant
peripheral nerve sheath tumors (MPNSTs) are cancerous in nature. The lesions
may appear as white, firm nodules. They tend to be locally aggressive. Although
rare, these tumors can cause potential damage. However, peripheral nerve sheath
tumors do not metastasize through the lymphatic system. Neural sheath tumors
are most commonly found in aged animals. Early detection is very important for
better diagnosis.Â
Causes- Although the etiology is unknown, they are believed to develop in areas
around former injury. Normally schwan cells from which these tumors originate
help in the restoration of tissues and cells damaged during injury. It is
thought that during the process of repair, tumorogenesis takes place. However,
there is no published information supporting the fact.
Symptoms- It is very difficult to diagnose malignant peripheral nerve sheath
tumors of the thoracic limb (forelimb).Clinically, most patients exhibit
chronic progressive thoracic limb lameness, which cannot be distinguished from
musculoskeletal lameness. A palpable axillary mass is seen in some of the cases.
Normally the clinical signs include severe, unexplained, intractable pain,
chronic, progressive forelimb lameness and muscle atrophy, lameness in the hind
limbs, monoparesis (partial loss of movement of one extremity), ataxia (lack of
coordination of muscle movements) and proprioceptive deficits (condition in
which the dog is not aware of its movement and posture), peripheral nerve
disorder (from self-mutilation), palpable mass (mass can be felt by touch
examination), hypotonia (condition that causes reduced muscle strength),
hyporeflexia (condition caused by absence of reflexes). Hornerâs syndrome
(symptom caused by damage to the sympathetic nervous system) and paresis are
generally caused if the spinal cord is suppressed. If the schwannoma is in the
neck, only one side of the face will be affected and eyelids would be droopy.
Other symptoms include decreased pupil size and slight elevation of the lower
eyelid. The reported duration of time before diagnosis has been found to be
between 2-24 months.
Diagnostic techniques- The diagnostic techniques include a thorough physical
examination of your dog. This comprises a blood chemical profile, a complete
blood count, urinalysis and an electrolyte panel. A computed tomography (CT)
or, ideally, a magnetic resonance imaging (MRI) provides the most accurate
information regarding the extent and location of the disease. An electromyogram
is essential because (a measurement of muscle activity) it shows abnormal
muscle activity in the event of a schwannoma.
Ultrasonography and immunohistochemical analysis are important for diagnosis of
distal malignant peripheral nerve sheath tumors. The tumor characteristics are
normally hypoechoic to mixed echogenic. Ultrasonography alone is not reliable
in differentiating peripheral nerve sheath tumors from a normal or abnormal
lymph node. Therefore, the ideal method of assessment is to identify a nerve
associated with the malignant peripheral neural sheath tumor. For doing this,
doctors take the help of ultrasonography only, but with a difference. Doctors
project a beam of 90 degrees on the surface of the lesion and the nerve. The
affected nerve will show increased echogenecity compared to other surrounding
nerves. Myelography is important as it helps in evaluating the entire spinal
cord and also determines the anatomical location of the lesion. However, it is
most beneficial when combined with computed tomography because it helps in
assessing the whole spinal cord and
vertebral column. It can also help in understanding the degree of spinal cord
compression and nerve root involvement.
Treatment- Surgical extirpation of the tumor is the treatment of choice for
peripheral nerve sheath tumors. Amputation becomes inevitable at times. Local
recurrence post surgery is common. A laminectomy (it is a spine operation to
remove the portion of the vertebral bone) is indicated with a schwannoma
involving the nerve roots. Radiotherapy may be beneficial depending on the size
of the tumor and its location.Â
Prognosis- Malignant peripheral nerve sheath tumors usually have a guarded
prognosis because in at least 72% of cases, the disease recurs after surgery.
Since these lesions are not detected early, the limbs have to be amputated in
most of the cases. The median survival time for dogs with malignant peripheral
nerve sheath tumors is 2 years. More closer the tumor is to the paw, greater
are the chances of recovery. However, reports suggest that benign peripheral
nerve sheath tumors have an excellent prognosis. Â
References
Pet MD
Biomed experts
Nerve sheath tumors in the dog- Bradley RL, Withrow SJ, Snyder SP
Tumours Involving the Nerve Sheaths of the Forelimb in Dogs-Â Targett MP, Dyce
J, Houlton JEFÂ
Small Animal Clinical Oncology- Withrow Stephen J, and David M. Vail
Cancer in Dogs and Cats: Medical and Surgical Management- Morrison Wallace B
Tumors in Domestic Animals- Donald J Meuten
Â
Â
Morgan Lewis, RPh.
Member GSDCA
President Last Hope of Georgia 501c3
"So Much to Do, So Little Time"
________________________________
From: Catherine Morton <managsd@xxxxxxxxx>
To: "Showgsd-l@xxxxxxxxxxxxx" <Showgsd-l@xxxxxxxxxxxxx>
Sent: Saturday, March 30, 2013 5:53 PM
Subject: [ SHOWGSD-L ] Nerve sheath tumors- anyone had this?
Hi all,
Has anyone had any experience with nerve sheath tumors in dogs?
I have a young dog (not quite 6 years) diagnosed via MRI with one in the low
area of the L-S region of the spine.
I haven't discussed options yet with our surgeon, just glad we have some
answers for our hind limb ataxia.
Thanks,
Catherine Morton
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POST is Copyrighted 2012. All material remains the property of the original
author and of GSD Communication, Inc. NO REPRODUCTIONS or FORWARDS of any kind
are permitted without prior permission of the original author AND of the
Showgsd-l Management. ALL RIGHTS RESERVED.
Each Author is responsible for the content of his/her post. This group and its
administrators are not responsible for the comments or opinions expressed in
any post.
ALL PERSONS ARE ON NOTICE THAT THE FORWARDING, REPRODUCTION OR USE IN ANY
MANNER OF ANY MATERIAL WHICH APPEARS ON SHOWGSD-L WITHOUT THE EXPRESS
PERMISSION OF ALL PARTIES TO THE POST AND THE LIST MANAGEMENT IS EXPRESSLY
FORBIDDEN, AND IS A VIOLATION OF LAW. VIOLATORS OF THIS PROHIBITION WILL BE
PROSECUTED.
For assistance, please contact the List Management at admin@xxxxxxxxxxx
VISIT OUR WEBSITE - http://showgsd.org
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